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Weblogic 8.1 Adminstration Guide
http:\\localhost:7001\console
adminserver - 7011
mainserver - 7013
mydomain - configuration name
system : user id
weblogic : password
Name: MyJDBC Data Source
JNDI Name : MYDSJNDI
scott / tiger GDATA
Connection Pool Name : MyJDBCConnectionPool
C:\bea\user_projects\domains\mydomain
startWeblogic (for Admin server)
startManagedWeblogic mainserver localhost:7011 (7011 - admin port)
################################################################
########################
WEBLOGIC 8.1
Excercise : Configure and Start a New Domain (configuration name is
"mydomain") and Servers
--------------------------------------------------------------------------------------------------------------1. Start the Configuration Wizard
2. Select "Create a new Weblogic Configuration " Click Next
3. Use "Basic Weblogic Server Domain" as the Configuration Template
4. Check the "Custom" radio button for Customer Configuration. Click Next
5. For the Administration Server Configuration , Specify
Name: adminserver
Listen Addss: localhost
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Listen Port : 7011
SSL Listen Port : 7012
SSL ENABLED : YES
CLICK NEXT
6. CHECK Yes on the " Managed Servers, Clusters, and Machine Options"
Click Next
7. Click add Icon. Specify a Managed server as
Name : mainserver
List Addss : localhost
List Port : 7013
SSL : 7014
SSL ENABLED : YES
CLICK NEXT
8. Click Next on the Configure Clusters
9. Click Next on the Configure Machines
10. Enusre "No" on JDBC
11. Ensure "No' on JMS
12. User Name : system, Password : weblogic
13. Ensure "No" in the radio button and click next
14. Select "No" for Create Start Menu
15. Select the Development Mode radio button as the Weblogic
Configuration Startup mode. select SUN JDK
16. specify "mydomain" as the COnfiguration Name
17. Click Done to exit wizard
Start Admin server
-------------------------------1. goto C:\bea\user_projects\domains\mydomain
2. setenv
3. startWeblogic (for Admin server)
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<server started in Running Mode >
Start MainServer
-------------------------------1. goto C:\bea\user_projects\domains\mydomain ( Configuration Name
is mydomain)
2. setenv
3. startManagedWeblogic mainserver localhost:7011 (7011 - admin port)
<server started in Running Mode >
Admin Console
------------http://localhost:7011/console
system : user id
weblogic : password
URL ::: jdbc:oracle:thin:@localhost:1521:GDATA
Driver Class Name ::: oracle.jdbc.driver.OracleDriver
scott / tiger GDATA
Connection Pool Name : MyJDBCConnectionPool
First Create Connection Pool
---------------------------Mydomain - > services - > Jdbc - > Connection Pool . Click on a new JDBC
Connection Pool
Choose Database
--------------Connection Pool Name : MyJDBC Connection Pool
Database Type : Oracle
Database Driver : Oracle's Thin Versions: 8.1.7, 9.0.1,9.2.0
Database Name : GDATA
Host Name :localhost
Database User : scott
Database Pass : tiger
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Next Create Datasource
-----------------------Mydomain - > services - > Jdbc - > DataSource . Click on a new JDBC
Datasource
Configure Datasource
--------------------Name: MyJDBC Data Source
JNDI Name : MYDSJNDI
Practical Day
This December 2004
JSP StrutsServletJava ScriptJDBC (over)
- DriverManager / DataSource
- Statement / ResultSet
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EJB- (pending)
XML – JDOM (pending)
LDAP (over coding, now doc reading pending)
MQ Series (NOW)
Jan 2004
XMLOracle-
Regular
Rational Rose
Java CoreEJB-
Tutorial Link
-------------------------------------------------------------------------------------------------------Dos Prompt – EJB Deploy
Make Jar the ejb module
jar cvf tt.jar classes\com\ejb\stateless\H*.class META-INF\*.xml – wrong
bcos package is com.ejb.stateless NOT from classes.com.ejb.*
jar cvf tt.jar com\ejb\stateless\H*.class META-INF\*.xml - right
Use ejbc
java weblogic.ejbc tt.jar mm.jar
java weblogic.ejbc -compiler javac tt.jar mm.jar
java weblogic.ejbc -compiler javac.exe tt.jar mm.jar
--------------------------------------------------------------------------------------------------------
EJB Lecture
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http://www.javaperformancetuning.com/tips/j2ee_ejb.shtml
Java Glossary
http://mindprod.com/jgloss/anonymousclasses.html
Java Lecture
http://www.cs.umd.edu/class/spring2002/cmsc433-0201/Lectures/javapart7.pdf
http://www.cs.umd.edu/class/spring2002/cmsc433-0201/Lectures/javapart6.pdf
--------------------------------------------------------------------------------------------------------
1.
What are the types of Clustering in J2EE? ( J2EE)
J2EE clusters usually come in two flavors: shared nothing and shared disk.
In a shared-nothing cluster, each application server has its own file systems
with its own copy of applications running in the cluster. Application updates and
enhancements require updates in every node in the cluster. With this setup, large
clusters become maintenance nightmares when code pushes and updates are
released.
In contrast, a shared-disk cluster employs a single storage device that all
application servers use to obtain the applications running in the cluster. Updates
and enhancements occur in a single file system and all machines in the cluster
can access the changes.
-------------------------------------------------------------------------------------------------------2.
String Buffer Vs String? ( Core Java )
Strings however are immutable meaning they cannot be modified once created.
Whenever you reassign the value of a String variable, in the background you are
really creating another String object and telling the JVM to use the newly created
String object as the placeholder for a variable. The String object is also the only
object which overrides the "+" concatenation operator. This allows for Strings to
be created based on the concatenation of one or more String objects.
Consider a case where a String variable needs to be modified several times.
Each time the value of that String variable is modified a new String object must
be created. This will result in several String objects in memory awaiting garbage
collection. Not to mention the additional CPU overhead of creating these new
String objects.
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The more efficient way to handle this is through the use of a String Buffer
object. String Buffer object again stores an array of characters with some
subtle differences.
1. It does not overload the "+" concatenation operator.
2. Its contents can be modified without creating a new String Buffer
instance.
Modifying the code above to take advantage of the String Buffer object
requires only a few simple changes. Using the StringBuffer object only
one object is used during the lifespan of the for loop. String Buffer acts
like a pointer.
StringBuffer a = new StringBuffer("ab");
StringBuffer b = a;
a.append("cd");
System.out.println(b);
OP : - abcd
-------------------------------------------------------------------------------------------------------3.
What are JSP Scope objects? ( JSP )
scope object are page , request , session , or application scope
-------------------------------------------------------------------------------------------------------4.
Types of Java.lang.reflect.Modifier in Java? ( Core Java )
Public, Private, Protected, Static, final, synchronized, volatile, transient, native,
interface, abstract, strict
Transient - You can reduce the size of your serialized object by marking some
fields transient. The values of these fields won't be written. When the object is
read back, it is up to you to reconstitute the fields. Note that you must manually
reconstitute all the transient fields.
Volatile (lock) - The volatile keyword is used on variables that may be modified
simultaneously(at the same time) by other threads. This warns the compiler to
fetch them fresh each time, rather than caching them in registers. This also
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inhibits certain optimizations that assume no other thread will change the values
unexpectedly. Since other threads cannot see local variables, there is never any
need to mark local variables volatile.
Synchronized() - During the execution of a synchronized method, the thread
holds the monitor for that method's object, or if the method is static, it holds the
monitor for that method's class. If another thread is executing the synchronized
method, your thread is blocked until that thread releases the monitor (by either
exiting the method or by calling wait()).
A crucial method that must not be executed by two threads simultaneously. Only
one thread at a time can own the lock for any given object. Thus if more than one
thread tries to enter a section of code for which the lock must be acquired then
only one thread will get the lock and all other threads will block. Note however
that a thread can still execute a non-synchronized method or block of code even
if the object is locked.
In many applications is safe to have many reader threads simultaneously
accessing a data structure, but only one writer thread. If there is a writer thread
active, then all other reader and writer threads must be blocked. Arranging this is
somewhat trickier that locking the entire datastructure for every read/write.
-------------------------------------------------------------------------------------------------------5.
What is Reflection in Java? ( Core Java )
Reflection is a feature in the Java programming language. It allows an
executing Java program to examine or "introspect" upon itself, and
manipulate internal properties of the program. For example, it's possible
for a Java class to obtain the names of all its members and display them.
import java.lang.reflect.*;
public class DumpMethods {
public static void main(String args[])
{
try {
Class c = Class.forName(args[0]);
Method m[] = c.getDeclaredMethods();
for (int i = 0; i < m.length; i++)
System.out.println(m[i].toString());
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}
catch (Throwable e) {
System.err.println(e);
}
}
}
-------------------------------------------------------------------------------------------------------6.
Where Length , Length() and Size() is used ? ( Core java )
Length() – Returns length of the String & StringBuffer
Size() – Returns the number of elements in this list (Array List and Vector)
Length – Returns the number of elements in the String or Integer Array
7.
What are the default <tld> files available in Struts? ( Struts)
Struts-bean.tld
Struts-html.tld
Struts-logic.tld
-----------------------------------------------------------------------------------------------------------------------8.
What is start , notify, notifyAll, run in threads? ( Core Java)
Start() - Causes this thread to begin execution; the Java Virtual Machine
calls the run() method of this thread
Yield() - Causes the currently executing thread object to temporarily
pause and allow other threads to execute.
Sleep() - Causes the currently executing thread to sleep
Join() - Waits for this thread to die
Destroy() - Destroys this thread, without any cleanup.
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Notify() - Wakes up a single thread that is waiting on this object's monitor
Notify All() - Wakes up all thread that are waiting on this object's monitor
Wait() - Causes current thread to wait until another thread invokes the
notify() or notifyAll() method for this object
-----------------------------------------------------------------------------------------------------------------------9.
What is cloneable ? ( Core Java)
To make a field-for-field copy of instances of that class, using Object.
clone() method. Cloneable is a marker interface.
------------------------------------------------------------------------------------------------------------------------
10.
What is marker interface ? ( Core Java)
Empty interface (does not have any method definition, used for object
cloning )
Eg:- Serializable interface is a marker interface
-----------------------------------------------------------------------------------------------------------------------11.
What is Synchronization? Why it is required? ( Core Java )
A monitor is simply a lock that serializes access to an object or a class. To gain
access, a thread first acquires the necessary monitor, then proceeds. This
happens automatically every time you enter a synchronized method. You create
a synchronized method by specifying the keyword synchronized in the
method's declaration.
During the execution of a synchronized method, the thread holds the monitor for
that method's object, or if the method is static, it holds the monitor for that
method's class. If another thread is executing the synchronized method, your
thread is blocked until that thread releases the monitor (by either exiting the
method or by calling wait()).
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-----------------------------------------------------------------------------------------------------------------------12.
What is Throwable? ( Core Java)
Throwable class is the super class of all errors and exceptions in the Java
language
-----------------------------------------------------------------------------------------------------------------------( Core Java)
13.
What is Map, Hashmap, Hashset, Hashtable, Set, List,
Hashcode, weakHashMap ?
Map - An object that maps keys to values. A map cannot contain
duplicate keys; each key can map to at most one value.
HashMap / HashSet - It is unsynchronized and permits nulls.
Map m = Collections.synchronizedMap(new HashMap(...));
Set s = Collections.synchronizedSet(new HashSet(...));
TreeMap –
It is unsynchronized and keys are sorted
WeakHashMap - entry in a WeakHashMap will automatically be removed
when its key is no longer in ordinary use. - It is unsynchronized and
permits nulls.
SortedMap - A map that further guarantees that it will be in ascending key
order
Set - collection that contains no duplicate elements
Hashtable – It is Synchronized and non-null object used as Key or as a
value.
Properties - Each key and its corresponding value in the property list is a
string
----------------------------------------------------------------------------------------------------------------------------
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14. Convert String to int, float, double value ( Core Java)?
a) String str = "1";
int intValue = Integer.parseInt(str);
System.out.println(intValue);
b) double dValue = Double.parseDouble(str);
System.out.println(dValue);
c) float fValue = Float.parseFloat(str);
System.out.println(fValue);
---------------------------------------------------------------------------------------------------------------------------. Convert int value to String ? ( Core Java)
int intValue = 1;
String str = String.valueOf(intValue);
System.out.println(str);
float fValue = 1.02f;
String str = "";
str = Float.toString(fValue);
System.out.println(str);
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----------------------------------------------------------------------------------------------------------------------------------Convert String to Integer Object? ( Core Java)
String str = "100";
Integer Inte = null;
Inte = Integer.valueOf(str);
System.out.println(Inte);
----------------------------------------------------------------------------------------------------------------------------------Convert Integer object to intValue ? ( Core Java)
int intValuex = (new Integer(1000)).intValue();
System.out.println(intValuex);
----------------------------------------------------------------------------------------------------------------------------------14.
15. What is multithread and Single Thread in JSP object? (JSP)
Single Thread – One user one request
Multi Thread – One request for multiple user
----------------------------------------------------------------------------------------------------------------------------16.
Difference between Interface and Abstract Class ? ( Core Java)
Interfaces provide a form of multiple inheritance.
An abstract class can have static methods, protected parts, and a partial
implementation. Interfaces are limited to public methods and constants
with no implementation allowed.
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If you add a new method to an abstract class, you have the option of
providing a default implementation of it. Then all existing code will
continue to work without change.
If you add a new method to an interface, you must track down all
implementations of that interface in the universe and provide them with a
concrete implementation of that method.
Program - Abstract
abstract class abstra {
public void getSeconds(){
System.out.println("getSeconds");
getSec();
}
public void getSec(){
System.out.println("getSec");
getTime();
}
abstract public void getTime();
}
public class first extends abstra {
public void getTime(){
System.out.println("getTime");
}
public static void main(String ss[]){
//first f = new first();
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abstra f = new first();
f.getSeconds();
}
Program - Interface
interface abstra {
public void getSeconds();
}
public class second implements abstra {
public void getSeconds(){
System.out.println("getSeconds");
}
public void getSec(){
System.out.println("getSec");
}
public static void main(String ss[]){
second f = new second();
f.getSeconds();
}
}
-----------------------------------------------------------------------------------------------------------------------------
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17.
Difference between Vector and Array List (Core Java)
ArrayList will never supercede Vector because Vector is synchronized and
ArrayList is not. Therefore if you have an situation with multiple threads /
users hitting on the same list then you either need to use Vector or wrap
ArrayList in something that IS synchronized.
If you want a synchronized ArrayList you can pass it to the
Collections.synchronizedList() function and get back a synchronized
version of the list you passed in.
----------------------------------------------------------------------------------------------------------------------------18.
Difference between Aggregation and Inheritance? (Core Java)
Aggregation relates instances. Inheritance relates Classes.
-----------------------------------------------------------------------------------------------------------------------------
19.
Which is used for interacting with Mainframe from Java ?
(Core Java)
1.
2.
3.
4.
Java Adapter for Mainframe (Bea Weblogic)
IMS Connector
JOLT
Java Connector Architecture
----------------------------------------------------------------------------------------------------------------------------20.
What is Session Management ? ( JSP)
HttpSession (session replication), Cookies, URL rewriting, Hidden
Variable
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----------------------------------------------------------------------------------------------------------------------------21.
Difference between Request.getDispatcher() and
Response.sendRedirect()? (JSP)
----------------------------------------------------------------------------------------------------------------------------22.
Life cycle of Servlet? ( JSP )
1.
Create and initialize the servlet (init() method)
When a server loads a servlet, the server runs the servlet's init method.
Initialization completes before client requests are handled and before the
servlet is destroyed.
Even though most servlets are run in multi-threaded servers, servlets have
no concurrency issues during servlet initialization. The server calls the init
method once, when the server loads the servlet, and will not call the init
method again unless the server is reloading the servlet. The server can
not reload a servlet until after the server has destroyed the servlet by
running the destroy method.
2.
Handle zero or more service calls from clients (Service() method)
Invokes the service method, passing a request and response object.
3.
Destroy the servlet and then garbage collect it (destroy() method)
When a server destroys a servlet, the server runs the servlet's destroy
method. The method is run once; the server will not run the destroy
method again until after the server reloads and reinitializes the servlet.
When the server calls the destroy method, another thread might be
running a service request
----------------------------------------------------------------------------------------------------------------------------23.
Difference between sequential diagram and Colloboration
diagram? ( UML)
sequential diagrams are used to model sequential logic.
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communication diagrams, formerly known as collaboration diagrams in
UML 1.x, can be used for because they provide a birds-eye view of a
collection of collaborating objects.
A collaboration diagram shows object interactions organized around the
objects and their links to each other. Unlike a sequence diagram, a
collaboration diagram shows the relationships among the objects
independently of the time sequence. Collaboration diagrams and
Sequence diagrams express similar information, but show it in different
ways.
-----------------------------------------------------------------------------------------------------------------------------
24.
What are the SQL Statements ? ( Database )
Statement- It will execute simple query
PreparedStatement- It will execute precompiled query
CallableStatement- It will execute StoredProcedure
-----------------------------------------------------------------------------------------------------------------------------
25.
What is Garbage Collection ? (Automatic Memory
Management) ( Core Java )
When such an object is no longer referenced then during garbage
collection Java will invoke the finalize method before reclaiming the
storage.
System.gc();
Note that the finalize method is only called once. Note that finalize
methods may be called in any order and from any thread. The main
purpose of such methods is to allow the freeing of system (i.e. non-Java)
resources associated with the object.
Garbage collection cannot be forced.
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The garbage collector runs in low memory situations
When it runs it releases the memory allocated by an object.
One of the most important features of the Java is garbage collection, also called
automatic memory management. In Java while the program is running, the
memory is being allocated with new operation. This allocated memory storage is
not available until garbage collector sweeps away the unused objects. To make
any object unusable make the reference variable pointing to that object as null
pointer.
In Java all the objects are garbage collected, when you make a null reference to
the object. In Java you never explicitly free the memory allocated, instead the
Java does automatic garbage collection.
Example:
public int GarMethod() {
String s = new String("Test String");
System.out.println(s");
s = null;
}
In Java garbage collection is guaranteed only when the objects has null
reference to it. The Java runtime system keeps track of the memory allocated
and is able to determine whether the memory is still is usable or not.
In the above example the object 's' is garbage collected by the Java Runtime
System. But there is no guarantee that when the object is garbage collected.
In Java, you can call System.gc() and Runtime.gc() methods , if you call these
methods explicitly, the JVM makes efforts towards recycling the unused objects,
but there is no guarantee that when the objects are garbage collected.
In Java, it is a good idea to explicitly assign null into a variable when you have
finished with it.
Java does allow you to add a finalize() method to the class. The finalize() method
will be called before the garbage collector sweeps away the object. In practice,
we do not rely on the finalize() method for recycling any resources that are in
short supply - you simply cannot know when this method will be called.
Note: objects are garbage collected, not the reference
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-----------------------------------------------------------------------------------------------------------------------------
26.
What is MVC ? ( Design Pattern )
Model – Business logic
View – JSP
Controller – Servlet
Advantage :- Code Reusablility
-----------------------------------------------------------------------------------------------------------------------------
27.
Define Load Testing, Volume Testing, Regression Testing, Unit
Testing, Black box Testing, White Box Testing? ( Quality )
Load Testing – Simulating the Number of Users hit the Application,
simulateneously.
Volume Testing – Hitting the database
Regression Testing – Testing the application before production stage
Unit Testing – Testing the each module
Black box Testing - Testing without background functionality or program
logic
White box Testing– Testing the program logic and different conditions
scenario.
-----------------------------------------------------------------------------------------------------------------------------
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28.
Define Code Walk through and Code Review ? ( Quality )
Code Review – Inspecting the code formally
Code Walk through – Inspecting the code informally.
----------------------------------------------------------------------------------------------------------------------------29.
Java Data Types? ( Core Java )
Byte – 8 bits
Char (Unicode) , Short int – 16 bits
Float , int – 32 bits
Long, double – 64 bits
--------------------------------------------------------------------------------------------- -------------------------30. What is Serialization? Why it is required in non-Clustering?
(Core Java)
Serialization is a way of "flattening", "pickling" or "freeze-drying" objects so
that they can be stored on disk, and later read back and reconstituted,
with all the links between objects intact.
----------------------------------------------------------------------------------------------------------------------30. What is HTTP Load Balancing and Session Replication ? (
J2EE)
For Web applications, a hardware- or software-based HTTP load-balancer
usually sits in front of the application servers within a cluster. These loadbalancers can be used to decrypt HTTPS requests quickly, distribute the load
between nodes in the cluster, and detect server failures. The usual setup is to
have a user session live entirely on one server that is picked by the loadbalancer. This is called a "sticky" session.
HTTP session replication is expensive for a J2EE application server. If you can
live with forcing a user to log in again after a server failure.
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The term session replication is used when the current service state is being
replicated across multiple application instances. Session replication occurs
when the information stored in an HttpSession is replicated from, in this example,
one servlet engine instance to another. This could be data such as items
contained in a shopping cart or information being entered on an insurance
application. Anything being stored in the session must be replicated for the
service to failover without a disruption.
The solution chosen for achieving Session replication is called in-memorysession-replication. It uses a group communication protocol written entirely in
Java, called JavaGroups. JavaGroups is a communication protocol based on
the concept of virtual synchrony and probabilistic broadcasting.
To support automatic failover for servlet and JSP HTTP session states,
WebLogic Server replicates the session state object in memory. This process
creates a primary session state, which resides on the WebLogic Server to which
the client first connects, and a secondary replica of the session state on another
WebLogic Server instance in the cluster. The replica is always kept up-to-date so
that it may be used if the server that hosts the servlet fails. The process of
copying a state from one instance to another is called in-memory replication.
Session Replication :In a clustered environment, you want session information
to be immediately available to other servers in the cluster
HTTP load-balancer probably provides all of the fail-over and load-balancing
functionality you need, as far as HTTP requests go.
----------------------------------------------------------------------------------------------------------------------31.
What is factory method ? (Core Java)
is a sort of generic constructor that might produce any of a number of
different kinds of objects
eg:- Clone() method
------------------------------------------------------------------------------------------------------------------------32.
What is Cookies? ( JSP )
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Creates a cookie, a small amount of information sent by a servlet to a Web
browser, saved by the browser, and later sent back to the server. A cookie's
value can uniquely identify a client, so cookies are commonly used for session
management.
The servlet sends cookies to the browser by using the
HttpServletResponse.addCookie(javax.servlet.http.Cookie) method, which adds
fields to HTTP response headers to send cookies to the browser, one at a time.
The browser is expected to support 20 cookies for each Web server, 300
cookies total, and may limit cookie size to 4 KB each.
The browser returns cookies to the servlet by adding fields to HTTP request
headers. Cookies can be retrieved from a request by using the
HttpServletRequest.getCookies() method. Several cookies might have the same
name but different path attributes.
-------------------------------------------------------------------------------------------------------------------------
33.
Define ActionForward, ActionMappiong, ActionForm? ( Struts )
ActionForm is a JavaBean optionally associated with one or more
ActionMappings. Such a bean will have had its properties initialized from
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the corresponding request parameters before the corresponding
Action.execute method is called.
ActionForms are JavaBeans, subclasses should also implement
Serializable, as required by the JavaBean specification
An Action is an adapter between the contents of an incoming HTTP request and
the corresponding business logic that should be executed to process this
request. The controller (RequestProcessor) will select an appropriate Action for
each request, create an instance (if necessary), and call the execute method.
Actions must be programmed in a thread-safe manner, because the controller
will share the same instance for multiple simultaneous requests. This means you
should design with the following items in mind.
When an Action instance is first created, the controller will call setServlet with a
non-null argument to identify the servlet instance to which this Action is attached.
When the servlet is to be shut down (or restarted), the setServlet method will be
called with a null argument, which can be used to clean up any allocated
resources in use by this Action.
An ActionForward represents a destination to which the controller,
RequestProcessor, might be directed to perform a RequestDispatcher.forward or
HttpServletResponse.sendRedirect to, as a result of processing activities of an
Action class
An ActionMapping represents the information that the controller,
RequestProcessor, knows about the mapping of a particular request to an
instance of a particular Action class.
ActionServlet provides the "controller" in the Model-View-Controller. There can
be one instance of this servlet class, which receives and processes all requests
that change the state of a user's interaction with the application
-------------------------------------------------------------------------------------------------------------------------
34.
Diff VBScript Vs Java Script? ( Script)
VBScript – Microsoft ActiveX control can be used. Client side validation can be
done only in IE.
Java Script – Client side validation can be done in IE and Netscape browser.
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-------------------------------------------------------------------------------------------------------------------------
35.
Package Vs Stored Procedure? ( Database)
Package – collection of Function and Procedure
Function – must return value
Procedure – may or may return value (return using out parameter)
Stored Procedure – compiled piece of re-usable procedure. One time
compile and execute at any number of time.
-------------------------------------------------------------------------------------------------------------------------
36.
What is MQ-Series? ( Messaging)
It is used to store messages in a queue. (FIFO).
-------------------------------------------------------------------------------------------------------------------------
37.
Diff between ORACLE vs SQL Server ? ( Database)
The SQL Server 2000 advantages:
 SQL Server 2000 is cheaper to buy than Oracle 9i Database.
 SQL Server 2000 holds the top TPC-C performance and
price/performance results.
 SQL Server 2000 is generally accepted as easier to install, use and
manage.
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The Oracle 9i Database advantages:
 Oracle 9i Database supports all known platforms, not only the Windowsbased platforms.
 PL/SQL is more powerful language than T-SQL.
More fine-tuning to the configuration can be done via start-up parameters.
Mainframe – Handling Terra data (DB2)
-------------------------------------------------------------------------------------------------------------------------
38.
Aggregate Functions in Oracle? ( Database)
This table shows the equivalent Microsoft® SQL Server™ function for
each Oracle function.
Function
Average
Count
Maximum
Minimum
Standard deviation
Summation
Variance
Oracle
AVG
COUNT
MAX
MIN
STDDEV
SUM
VARIANCE
SQL Server
AVG
COUNT
MAX
MIN
N/A
SUM
N/A
-------------------------------------------------------------------------------------------------------------------------
39.
45. Primary Key, Unique Key, Candidate Key? ( Database)
A candidate key is a combination of attributes that can be uniquely used to
identify a database record without any extraneous data. Each table may
have one or more candidate keys. One of these candidate keys is
selected as the table primary key.
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-------------------------------------------------------------------------------------------------------------------------
40.
46. Data Defination Language and Data Manipulation Language ? (
Database)
DDL – (Use - CADro)
Use, Create, Alter, Drop, truncate

Create
CREATE DATABASE employees
CREATE TABLE personal_info
(first_name char(20) not null, last_name char(20) not null,
employee_id int not null)

Use
The USE command allows you to specify the database you wish to work with
within your DBMS. For example, if we're currently working in the sales database
and want to issue some commands that will affect the employees database, we
would preface them with the following SQL command:
USE employees

ALTER
ALTER TABLE personal_info
ADD salary money null

DROP
The final command of the Data Definition Language, DROP, allows us to remove
entire database objects from our DBMS. For example, if we want to permanently
remove the personal_info table that we created, we'd use the following
command:
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DROP TABLE personal_info
Similarly, the command below would be used to remove the entire employees
database:
DROP DATABASE employees
DML – (I-SUDel )
Insert, select, Update, Delete
-------------------------------------------------------------------------------------------------------------------------
42. Oracle Legal Data Types ? ( Database)
Legal Data Types
VARCHAR2(size)
Variable length character string having max. length of size
CHAR(size)
Fixed length character string with number of bytes equal to size
NUMBER(p,s)
Number having a precision p and s digits to the right of the decimal. If you
leave off p and s (e.g., NUMBER), then it is a floating point number.
LONG
Character data of variable length up to 2 gigabytes (cannot be a key)
DATE
A date field
RAW(size)
Raw binary data of length size. Max. size is 255 bytes
LONG RAW
Raw binary data up to 2 gigabytes (cannot be a key)
-------------------------------------------------------------------------------------------------------------------------
43. What is USER_TABLES ? ( Database)
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Oracle keeps the names of your tables and other information in a meta
table called user_tables
------------------------------------------------------------------------------------------------------------------------44. How to Generate Number in Oracle Database ? ( Database)
SELECT (NVL((MAX(TO_NUMBER(SEQ_ID))),0))+1 from GEN_TABLE
-------------------------------------------------------------------------------------------------------------------------
45. Back Page Expiration ? ( Database)
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires",0);
------------------------------------------------------------------------------------------------------------------------46. To_Char in ORACLE (selecting user defined format) ( Database)
select to_char(quote_date,'yyyy-dd-mon') from rating_history
-------------------------------------------------------------------------------------------------------------------------
47. To_Date in ORACLE (inserting user date format) ( Database)
insert into datetimer values ( to_date('2/april/2002','dd/mon/yyyy') )
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48. What is JMS Vs MQSeries? ( Messaging )
The JMS server guarantees that it will keep the message in a
persistent storage until the receiver becomes online or when the
message has expired (using the expiration date).
MQSeries provides a consistent multi-platform, applicationprogramming interface. A key factor is time-independent processing.
This means that messages are dealt with promptly, even if one the
recipient is temporarily unavailable.
An application that implements the JMS specification must guarantee
the delivery of the message. So, either if you use MQ Series, Fiorano,
OpenJMS, and so on, they all must provide this feature.
OpenJMS uses JDBM as a persistant storage, but you can use
MySQL, Oracle, etc.).
-------------------------------------------------------------------------------------------------------------------------
49.
What are the delivery modes in JMS? ( Messaging )
Persistent means that the message is delivered once and only once.
On persistant mode we need to store all messages in a DB.
Non_persistent means that messages are delivered "at most once".
-------------------------------------------------------------------------------------------------------------------------
50. What is JMS API ? ( Messaging )
The Java Message Service is a Java API that allows applications to
create, send, receive, and read messages.
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

Asynchronous. A JMS provider can deliver messages to a
client as they arrive; a client does not have to request
messages in order to receive them.
Reliable. The JMS API can ensure that a message is
delivered once and only once
-------------------------------------------------------------------------------------------------------------------------
51. what is Message Driven Bean ? ( EJB)
The message-driven bean, enables the asynchronous consumption of
messages. A JMS provider may optionally implement concurrent
processing of messages by message-driven beans.
-------------------------------------------------------------------------------------------------------------------------
52. What is Messaging? ( Messaging )
1 What Is Messaging?
Messaging is a method of communication between software
components or applications. A messaging system is a peer-to-peer
facility: A messaging client can send messages to, and receive
messages from, any other client. Each client connects to a
messaging agent that provides facilities for creating, sending,
receiving, and reading messages.
Messaging enables distributed communication that is loosely
coupled. A component sends a message to a destination, and the
recipient can retrieve the message from the destination. However,
the sender and the receiver do not have to be available at the same
time in order to communicate. In fact, the sender does not need to
know anything about the receiver; nor does the receiver need to
know anything about the sender. The sender and the receiver need
to know only what message format and what destination to use. In
this respect, messaging differs from tightly coupled technologies,
such as Remote Method Invocation (RMI), which require an
application to know a remote application's methods.
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Messaging also differs from electronic mail (e-mail), which is a
method of communication between people or between software
applications and people. Messaging is used for communication
between software applications or software components.
-------------------------------------------------------------------------------------------------------------------------
53. What are the types in Messaging? ( Messaging )
Point-to-Point Messaging Domain



Each message has only one consumer.
A sender and a receiver of a message have no timing
dependencies. The receiver can fetch the message whether
or not it was running when the client sent the message.
The receiver acknowledges the successful processing of a
message.
Use PTP messaging when every message you send must be
processed successfully by one consumer.
A point-to-point (PTP) product or application is built around the concept
of message queues, senders, and receivers. Each message is
addressed to a specific queue, and receiving clients extract messages
from the queue(s) established to hold their messages. Queues retain
all messages sent to them until the messages are consumed or until
the messages expire.
publisher and Subscriber Domain
Publishers and subscribers are generally anonymous and may
dynamically publish or subscribe to the content hierarchy. The
system takes care of distributing the messages arriving from a
topic's multiple publishers to its multiple subscribers. Topics retain
messages only as long as it takes to distribute them to current
subscribers.
Pub/sub messaging has the following characteristics.


Each message may have multiple consumers.
Publishers and subscribers have a timing dependency. A
client that subscribes to a topic can consume only messages
published after the client has created a subscription, and the
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subscriber must continue to be active in order for it to
consume messages.
Use PTP messaging when every message you send must be
processed successfully by one consumer
-------------------------------------------------------------------------------------------------------------------------
54. What are the Messaging Consumption? ( Messaging)
Asynchronous - Whenever a message arrives at the destination, the
JMS provider delivers the message(Loosely coupled)
Synchronous - A subscriber or a receiver explicitly fetches the
message from the destination (Tightly coupled)
-------------------------------------------------------------------------------------------------------------------------
55. What is JNDI? ( Core Java)
In the JNDI, all naming and directory operations are performed relative
to a context. There are no absolute roots. Therefore the JNDI defines
an initial context, InitialContext , which provides a starting point for
naming and directory operations. Once you have an initial context, you
can use it to look up other contexts and objects.
The javax.naming package defines a Context
interface, which is
the core interface for looking up, binding/unbinding, renaming objects
and creating and destroying subcontexts.
The most commonly used operation is lookup() . You supply lookup()
the name of the object you want to look up, and it returns the object
bound to that name.
A binding is a tuple containing the name of the bound object, the name
of the object's class, and the object itself.
The JNDI architecture consists of an API and a service provider
interface (SPI). Java applications use the JNDI API to access a variety
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of naming and directory services. The SPI enables a variety of naming
and directory services to be plugged in transparently, thereby allowing
the Java application using the JNDI API to access their services. See
the following figure.
------------------------------------------------------------------------------------------------------------------------56. Diff doGet vs doPost()? ( Servlet )
Difference between them are
with get method, the query string is passed along with the request URL of
the page so one can see the query string at the address bar of the browser.
There is a limitation on the size of the Query String. As get method passes
form input elements with its URL so there is a limited amount of information
that can be passed with this method. The amount of information depends
upon the browser. If parameters is a Query String use getParameter. If it was
sent in the body, you may use getParameter or getInputStream.
doGet is called in response to an HTTP GET request ex:
<form name=sample action="url" method=get> or from a URL
While in Post the query string is passed at the end of request header. So the
request parameters can not be seen at the address or status bar. So post is
secure while taking password or Credit card information. But with Post
method you can send as much amount as you want. POST sends
parameters in the body of the request. Large objects/data can be passed this
way.
doPost is called in response to an HTTP POST request ex:
<form name=sample action="url" method=post>
POST has no limit on the amount of data you can send and because the data
does not show up on the URL you can send passwords. But this does not
mean that POST is truly secure. For real security you have to look into
encryption which is an entirely different topic
-------------------------------------------------------------------------------------------------------------------------
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57. What is Trigger ? ( Database)
Automatic execution at the time of DML operation, issued against table
level
Before and After TriggerBefore Trigger and After Trigger has Row Level and Statement Level
Trigger – Input, Update and Delete
------------------------------------------------------------------------------------------------------------------------58. What is View? ( Database)
It is a mirror of the table. DML and DDL operation can be done except
Reference Table (cascading is not permitted)
------------------------------------------------------------------------------------------------------------------------59. What is Stored Procedure? ( Database)
Stored Procedure is one time compiled and stored in anonymous block
------------------------------------------------------------------------------------------------------------------------60. What is Sequence?
Creating user defined automatic number insert in the column for each
record level insert
------------------------------------------------------------------------------------------------------------------------61. What is Indexing?
For faster access of records in the table. Automatic Index can be
done while inserting the record or after storing records in the table ,
then indexing the table.
-------------------------------------------------------------------------------------------------------------------------
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62. What is B-Tree and B-MAP indexing? (Data ware housing)
B-Tree is in OLTP (mainly reports-select statement, less insert and
update)
B-MAP is in OLAP (mainly trill – down reports)
------------------------------------------------------------------------------------------------------------------------63. Diff CMP v BMP? ( EJB )
CMP
(+)

Tx behavior in beans are defined in transaction attributes of the
methods

Tuned CMP entity beans offer better performance than BMP entity
beans.

Database independence since it does not contain any database
storage APIs within it.

CMP, the container handles the implementation of the code necessary
to insert, read, and update an object in a data source.

CMP is the ideal way to develop an application because it requires less
code changes by the application developer when the data model
changes.

CMP is Portable across all DB’s
(-)

Since the container performs database operations on behalf of the CMP
entity bean, they are harder to Debug
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BMP

A programmer has to write a code that implements Tx behaviour to the
bean class.

BMP beans offer more control and flexibility that CMP beans.

In BMP you will take care of all the connection and you write the SQL
code inside the bean whereas in CMP the container will take care of it.

The BMP is not portable across all DB's.

Developer creates the implementation for the insert, read, and update
of an object.
 If performance is the only factor, BMP performs a million times faster
than CMP. Well, may be not that much faster, but you get the point.

CMP is for ease of development, basically the container does all the
work for you, but it is not as flexible and you cannot fine tune the query
like you can do in BMP.
------------------------------------------------------------------------------------------------------------------------64. Diff Home Interface V Remote Interface ? ( EJB )
Home interface is an interface to the container used to create or
accesses an instance of an EJB.
Remote Interface is an interface to the EJB Instance used to call
business logic methods of the Bean class.
Metadata Interface used to perform dynamic invocation of the
methods of the bean (e.g. to find new services from beans installed
after client compilation)
------------------------------------------------------------------------------------------------------------------------65. Diff EJB 2.0 V EJB 1.1 ? ( EJB )
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EJB 1.1 Specification provided EJB clients with a remote interface
and a remote home interface (Java RMI interfaces, compatible
with RMI – IIOP ) to interact with EJB instances, achieving location
transparency
Request comes from a remote host.
In a similar fashion, the EJB 2.0 specification now provides EJB
clients with a local interface and local home interface to interact with
EJB instances that share the same Java Virtual Machine (JVM). Not
RMI Interface and not compatible with RMI-IIOP.
javax.ejb.EJBLocalObject and javax.ejb.EJBLocalHome
Request comes from a LOCAL host.
EJB2.0 has Containter – Managed Relationships, EJB QL, Local
Interface, Message Driven Bean
Message Driven Bean –



Transaction aware component of asynchronous message
Loosely coupling between sender and receiver.
Similar to stateless session bean in operation.
------------------------------------------------------------------------------------------------------------------------66. Define JNDI? ( Core Java )
Java Naming and Directory Interface (JNDI) is a naming service that
allows a program or container to register a "popular" name that is
bound to an object
------------------------------------------------------------------------------------------------------------------------67. Diff EJB v Java Beans?
Java Beans can do processing -- like XML-parsing or database
access, and can access Java Enterprise APIs. It will run with in JVM
Enterprise Java Beans it will run within EJB Server and has
Transaction Management.
68. What is EJB Architecture?
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


Build once, access any where
Business methods accessible via: RMI-IIOP, RMI-JRMP, Servlets
and JSPs.
Other language via CORBA
-------------------------------------------------------------------------------------------------------------------------
69. Diff Stateful and Stateless ?
Stateless has create method without argument and session will not
be maintained. Stateful has create method with argument and
session maintained.
----------------------------------------------------------------------------------------------------------------------70. Diff between CMP 2.0 and BMP ?
CMP 2.0 potentially simpler and portable (especially with CMR and
EJB QL).
BMP 2.0 has more detailed control.
Avoid excessive Remote Interface Calls.
Use EJB 2.0 for CMP and Local interface.
----------------------------------------------------------------------------------------------------------------------------71. What are Transaction Attributes Values ?
TX_BEAN_MANAGED ---- programmatically controls transaction
TX_REQUIRED - always required new or existing transaction
TX_SUPPORTS - if there is a transaction then run, otherwise run with
out transaction
TX_REQUIRES_NEW - only new transaction
TX_MANDATORY - must have transaction already
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TX_NOT_SUPPORTED – no need of transaction
----------------------------------------------------------------------------------------------------------------------------72. What is EJB QL and CMR ?
CMR makes it much easier for bean developers to build applications
based on tightly-coupled entities such as employees and departments
or customers-orders-line items.
Using a syntax similar to SQL, EJB QL enables you to write queries
based on Entity Beans without knowing anything about the underlying
relational schema.
------------------------------------------------------------------------------------------73. What is Exception Handling?
Throwable class is a super class for Exception and Error in Java
language.
Errors may include the VM running out of resources, dependency
classes being incompatible, or the AWT native methods failing to
operate correctly.
Exceptions being thrown and caught without the user’s knowledge.
IOException - you perform any communication or file work
InterruptedException - thread-related
OutOfBoundsException – Vector related
For instance, an endlessly recursive nesting of the same class will
cause a StackOverflowError.
----------------------------------------------------------------------------------------------------------------------------74. What is ‘finally’ block?
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finally is rarely necessary. Even when it can be useful, it is often just
as easy to clean up your references. (Closing file, closing connection,
making referenced object null).
After the catch completes, the finally will run.
But if you call System.exit(0) in the catch block, the finally will not
run. Likewise, if there is code in the catch block that executes
indefinitely, the Java runtime will never get around to executing the
part in finally. These are pretty extreme examples, however. In any
logical programming situation, you can count on the finally block
running once the catch block finishes. This includes the case where
the catch block does something to throw a new exception
---------------------------------------------------------------------------------------------------------------------------75. If a abstract method is defined in abstract class, abstract method
should be implemented in the extended class.
abstract class abstra {
public void getSeconds(){
System.out.println("abstra");
}
abstract public void getTime();
}
public class first extends abstra {
public void getSeconds(){
System.out.println("first");
}
public static void main(String ss[]){
first f = new first();
f.getSeconds();
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}
}
compile time error , since the abstract method is not implemented in
child class
----------------------------------------------------------------------------------------------------------------------------76. It is not necessary to have at least one abstract method in a
abstract class
abstract class abstra {
public void getSeconds(){
System.out.println("abstra");
}
}
public class first extends abstra {
public void getSeconds(){
System.out.println("first");
}
public static void main(String ss[]){
first f = new first();
f.getSeconds();
}
}
----------------------------------------------------------------------------------------------------------------------------77. Abstract class can be defined with out method or abstract
method.
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----------------------------------------------------------------------------------------------------------------------------78. Abstract class can’t be instantiated
abstract class abstra {
public void getSeconds(){
System.out.println("abstra");
}
}
public class first extends abstra {
public void getSeconds(){
System.out.println("first1");
}
public static void main(String ss[]){
//abstra f = new first(); - ok
first f = new abstra(); - abstract class can’t be instantiated
f.getSeconds();
}
}
----------------------------------------------------------------------------------------------------------------------------------79. Interface will allow only public method and default it is final static
variable in interface. Abstract class will allow protected, private or
public method and variable will be protected or public. It allows final
static variable also, but it is not default in abstract class.
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----------------------------------------------------------------------------------------------------------------------------------80. What is the output in the following code?
interface abstra {
void getSeconds();
final static int a = 10;
}
public class second implements abstra {
public void getSeconds(){
System.out.println("getSeconds");
}
public static void main(String ss[]){
final int a= 100;
System.out.println("value of a <<" + a + ">>");
second f = new second();
f.getSeconds();
}
}
out put is a = 100
----------------------------------------------------------------------------------------------------------------------------------80.
What is the output of following code ?
interface abstra {
void getSeconds();
static int a = 10;
}
public class second implements abstra {
public void getSeconds(){
a = 109;
System.out.println("value of a <<" + a + ">>");
}
public static void main(String ss[]){
second f = new second();
f.getSeconds();
}
}
out put is error, since variable a is declared in interface and default it is
final static variable
----------------------------------------------------------------------------------------------------------------------------------81.
What is the output of following code ?
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interface abstra {
void getSeconds();
static int a = 10;
}
public class second implements abstra {
int a ;
public void getSeconds(){
a = 109;
System.out.println("value of a <<" + a + ">>");
}
public static void main(String ss[]){
second f = new second();
f.getSeconds();
}
}
output is a = 109
----------------------------------------------------------------------------------------------------------------------------------82. What is the output of the code ?
interface abstra {
void getSeconds();
int a = 10;
}
public class second implements abstra {
int a ;
public void getSeconds(){
System.out.println("value of a <<" + a + ">>");
}
public static void main(String ss[]){
second f = new second();
f.getSeconds();
}
}
output a =0;
83. Final variable should be assigned a value. Static Variable assign default
value Zero.
----------------------------------------------------------------------------------------------------------------------------------84. what is the out put?
abstract class abstra {
private void getSeconds(){
System.out.println("abstra");
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}
}
public class first extends abstra {
private void getSeconds(){
System.out.println("first");
}
public static void main(String ss[]){
first f = new first();
f.getSeconds();
}
}
Output is “first”
-----------------------------------------------------------------------------------------------------------------------85. what is the out put?
abstract class abstra {
private void getSeconds(){
System.out.println("abstra");
}
}
public class first extends abstra {
public static void main(String ss[]){
first f = new first();
f.getSeconds();
}
}
Compile time error – parent method is private
Note := Parent method is public or protected, child class can access it.
----------------------------------------------------------------------------------------------------------------------------------86. what is the out put?
abstract class abstra {
private void getSeconds(){
System.out.println("abstra");
}
}
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public class first extends abstra {
void getSeconds(){
System.out.println("first");
}
public static void main(String ss[]){
abstra f = new first(); //Note child class object is referenced by Parent
class
f.getSeconds();
}
}
Out put is compile time error.
----------------------------------------------------------------------------------------------------------------------------------What is the output?
87. In Overriding, Parent class and Child class has same (100%) method
signature with modifier may be public or protected and Parent c = new
Child().
object always refer Child Class method
-----------------------------------------------------------------------------------------------------------------------------------
88. In Overriding, Parent class and Child class has same (100%) method
signature with modifier may be private or protected and Child c = new
Child().
Child object always refer Child Class method
-----------------------------------------------------------------------------------------------------------------------------------
In Abstract Class and Simple Class Overriding having (parent p =
new child or child c = new child) object reference, then Modifier rule
will be
Private Modifier > Protected Modifier > Public Modifier > Empty modifier
Child Modifier always >= Parent Modifier in Overriding
In Parent class and Child class Overriding having (parent p = new
child) object reference, then Modifier rule will be
Private Modifier > Protected Modifier > Public Modifier > Empty modifier
Child Modifier always >= Parent Modifier in Overriding
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-----------------------------------------------------------------------------------------------------------------------------------
89. Abstract Method should not have private modifier
----------------------------------------------------------------------------------------------------------------------------------90. What are the Types of Servlet?
Types of Servlets
Servlets must implement the interface javax.servlet.Servlet. There are two main
types of servlets:


Generic servlets extend javax.servlet.GenericServlet. Generic
servlets are protocol independent, meaning that they contain no
inherent support for HTTP or any other transport protocol.
HTTP servlets extend javax.servlet.HttpServlet. These servlets have
built-in support for the HTTP protocol and are much more useful in an
Browser environment
Servlets that extend HttpServlet are much more useful in an HTTP environment,
since that is what they were designed for. We recommend that all Servlets
extend from HttpServlet rather than from GenericServlet in order to take
advantage of this built-in HTTP support.
For both types of Servlets, you can implement the constructor method init()
and/or the destructor method destroy() if you need to initialize or deallocate
resources.
All Servlets must implement a service() method. This method is responsible for
handling requests made to the Servlet. For generic Servlets, you simply override
the service() method to provide routines for handling requests. HTTP Servlets
provide a service method that automatically routes the request to another method
in the servlet based on which HTTP transfer method is used, so for HTTP
Servlets you would override doPost() to process POST requests, doGet() to
process GET requests, and so on.
91. servlets run on an application server or web server rather than in a
web browser.
---------------------------------------------------------------------------------------------------------------------------191919
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19
[ 19th Nov 2004 onwards ]
92. Generic Servlet
You must implement abstract method – service()
HttpServlet
No need of implementing service() method
---------------------------------------------------------------------------------------------------------------------------93.
Steps of a JSP Request
1.
2.
3.
4.
Client Requests a JSP Page
The JSP Engine Compiles the JSP into a Servlet
The generated Servlet is compiled and loaded
The compiled servlet services the request and sends a response
back to the client
---------------------------------------------------------------------------------------------------------------------------93. Primordial Class Loaders and Class Loader objects.
Primordial Class Loaders provides Java with the ability to bootstrap itself and
provide essential functions. The Java API class files (stored by default in the
classes.zip file) are usually the first files loaded by the VM. The Primordial Class
Loader also typically loads any classes a user has located in the CLASSPATH
Class Loader objects load classes that are not needed to bootstrap the VM into
a running Java environment. The VM treats classes loaded through Class Loader
objects as untrusted by default. Class Loaders are objects just like any other
Java object-they are written in Java, compiled into byte code, and loaded by the
VM (with the help of some other class loader). These Class Loaders give Java its
dynamic loading capabilities.
There are three distinct types of Class Loader objects defined by the JDK itself:
Applet Class Loaders, RMI Class Loaders, and Secure Class Loaders
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Applet Class Loaders are responsible for loading classes into a browser
and are defined by the vendor of each Java-enabled browser.
RMI Class Loaders are very similar to Applet Class Loaders in that they
load classes from a remote machine.
Secure Class Loaders can only be used by classes found in the
java.security package and are extensively used by the Java 2 access
control mechanisms.
----------------------------------------------------------------------------------------------------------------------------
95.
Internationalization is the process of designing an application so that it can
be adapted to various languages
Localization is the process of adapting software for a specific region or
language by adding locale-specific components and translating text.
Resource bundles contain locale-specific objects.
java.util.Resource Bundle
MyResources_en.properties:
hello=Hello
bye=Goodbye
String baseName = "MyResources";
ResourceBundle rb = ResourceBundle.getBundle(baseName);
String key = "hello";
String s = rb.getString(key);
---------------------------------------------------------------------------------------------------------------------------96.
Uncommited transaction will be there in TLog
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----------------------------------------------------------------------------------------------------------------------------
97. - Transaction Level
ACID
Atomicity
Consistency
Isolation
Durabliity
98. – Transaction Atrributes
TX_REQUIRED – Client can provide transaction or new transaction
TX_MANDATORY – Client should have transaction
TX_REQUIRES_NEW – Suspend client transaction. Generate new
Transaction
TX_SUPPORTS – Transaction is optional
TX_NOT_SUPPORTED TX_BEAN_MANAGED – Code level transaction control
---------------------------------------------------------------------------------------------------------------------------99. – EJB Transaction
EJB transactions are a set of concepts and a set of mechanisms that attempt
to insure the integrity and consistency of a database for which multiple clients
may attempt to access it and/or update it simultaneously.
---------------------------------------------------------------------------------------------------------------------------100. – Isolation level
TRANSACTION_SERIALIZABLE
It prevents other users from updating or inserting rows into the data set until
the transaction is complete.
TRANSACTION_REPEATABLE_READ -
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It means that locks will be placed on all data that is used in a query, and
another transactions cannot update the data.
TRANSACTION_READ_COMMITTED
will never read data that another application has changed and not yet
committed
TRANSACTION_READ_UNCOMMITTED
you can read an uncommitted transaction that might get rolled back later. This
isolation level is also called dirty read. This is the lowest isolation level.
TRANSACTION_NON_REPEATABLE_READ When a transaction reads the same row more than one time, and between
the
two (or more) reads, a separate transaction modifies that row. Because the
row was modified between reads within the same transaction, each read
produces different values, which introduces inconsistency.
----------------------------------------------------------------------------------------------------------------------------
101.-
Different Model
Incremental Model - Big System development
Water fall Model - Go back to each phase
Spiral Model – Requirement is not clear
---------------------------------------------------------------------------------------------------------------------------[20th Nov 2004 onwards]
HONEY WELL INTERVIEW QUESTION - NOT SELECTED
20th Nov 2004 (NO
Session Façade
Externalization & Serialization
Abstract & Interface
Session Tracking
Transient & Volatile
ACID & Transaction Isolation Level
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File Writer
Servlet Context and Servlet Config
LOG 4j
Logger.setLevel)
102. Connection class has commit and roll back method
----------------------------------------------------------------------------------------------------------------------------
103. Instance Variable and Class Variable
Variable which is declared inside the method is LOCAL variable
Static variable which is declared in Class level is CLASS variable (We can’t
assign diff. value for diff. Instance)
Non-static variable is Instance variable (we can assign different value
for different instance)
----------------------------------------------------------------------------------------------------------------------------
104. What is the output ?
public class Test1 {
static int a = 10;
public static void main(String ss[]){
Test1 t1 = new Test1();
Test1 t2 = new Test1();
t1.a = 10;
t2.a = 100;
System.out.println("Value of t1.a is "+ t1.a);
System.out.println("Value of t2.a is "+ t2.a);
}
}
Value of t1.a is 100
Value of t2.a is 100
Since a variable is static
105.
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dirty read
A transaction reads data written by a concurrent uncommitted transaction.
nonrepeatable read
A transaction re-reads data it has previously read and finds that data has been
modified by another transaction (that committed since the initial read). ( Data
Change)
phantom read
A transaction re-executes a query returning a set of rows that satisfy a search
condition and finds that the set of rows satisfying the condition has changed due
to another recently-committed transaction.
(Row Change)
---------------------------------------------------------------------------------------------------------------------------
String Append in a File
import java.io.*;
public class Test {
public static void main(String ss[]) throws Exception{
FileOutputStream fos = new FileOutputStream("c:/test.txt",true);
Writer fWriter = new OutputStreamWriter(fos);
fWriter.write("hi man");
fWriter.close();
}
}
Or
public class Test {
public static void main(String ss[]) throws Exception{
FileWriter fWriter = new FileWriter("c:/test.txt",true);
fWriter.write("hi man");
fWriter.close();
}
}
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---------------------------------------------------------------------------------------------------------------------------107.
Static method should have static variable
static int a = 10;
public static void getY(){
System.out.println(" Y value" + a);
}
}
Output :- value10
int a = 10; ( ERROR ) declare static since it is used in static method
public static void getY(){
System.out.println(" Y value" + a);
}
}
108.
ABSTRACT

Abstract class must have atleast one abstract method definition –
FALSE (need not be)
86. Non-abstract methods need not to be implemented in Class - TRUE
109.
INTERFACE


All the methods in Interface are default abstract methods – TRUE
All the methods in Interface MUST BE implemented in the Class
(implementing class) - TRUE


Only public methods are allowed in Interface – TRUE
All the variables in the interface are default static final variable TRUE
----------------------------------------------------------------------------------------------------------------------------
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110.
Servlet configuration Vs ServletContext
public interface ServletContext
Defines a set of methods that a servlet uses to communicate with its servlet
container
The ServletContext object is contained within the ServletConfig object,
getAttribute()
getAttributeName()
getContext()
getRealPath()
getServlet()
getServletInfo()
A servlet configuration object used by a servlet container to pass information to
a servlet during initialization.
getServletName()
getServletContext()
getInitParameterNames()
getInitParameter()
---------------------------------------------------------------------------------------------------------------------------111.
Object Persistence and Serialization uses the Serializable and
Externalizable interfaces.




Each object to be stored is tested for the Externalizable
interface
If the object supports Externalizable, the writeExternal
method is called.
If the object does not support Externalizable and does
implement Serializable, the object is saved using
ObjectOutputStream.
Serializable objects are restored by reading them from an
ObjectInputStream.
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
Externalizable objects are restored by reading them using
readExternal method is called
Externalization:
The writeExternal and readExternal methods of the Externalizable interface are
implemented by a class to give the class complete control over the format and
contents of the stream for an object and its supertypes
Serializability of a class is enabled by the class implementing the
java.io.Serializable interface. Classes that do not implement this interface will not
have any of their state serialized or deserialized. All subtypes of a serializable
class are themselves serializable. The serialization interface has no methods or
fields and serves only to identify the semantics of being serializable.
Classes that require special handling during the serialization and deserialization
process must implement special methods with these exact signatures:
private void writeObject(java.io.ObjectOutputStream out)
throws IOException
private void readObject(java.io.ObjectInputStream in)
throws IOException, ClassNotFoundException
The writeObject method is responsible for writing the state of the object for its
particular class so that the corresponding readObject method can restore it.
----------------------------------------------------------------------------------------------------------------------------
112. Session Facade
Session facade is one design pattern that is often used while developing
enterprise applications.
It is implemented as a higher level component (i.e.: Session EJB), and it contains
all the iteractions between low level components (i.e.: Entity EJB). It then
provides a single interface for the functionality of an application or part of it, and it
decouples lower level components simplifying the design.
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Think of a bank situation, where you have someone that would like to transfer
money from one account to another.
In this type of scenario, the client has to check that the user is authorized, get the
status of the two accounts, check that there are enough money on the first one,
and then call the transfer. The entire transfer has to be done in a single
transaction otherwise is something goes south, the situation has to be restored.
As you can see, multiple server-side objects need to be accessed and possibly
modified. Multiple fine-grained invocations of Entity (or even Session) Beans add
the overhead of network calls, even multiple transaction. In other words, the risk
is to have a solution that has a high network overhead, high coupling, poor
reusability and mantainability.
The best solution is then to wrap all the calls inside a Session Bean, so the
clients will have a single point to access (that is the session bean) that will take
care of handling all the rest.
Obviously you need to be very careful when writing Session Facades, to avoid
the abusing of it (often called "God-Bean").
Session Facade performs the role of a broker to decouple the entity beans
from their clients
When implementing the Session Facade, you must first decide whether the
facade session bean is a stateful or a stateless session bean.
The Session Facade is a business-tier controller object that controls the
interactions between the client and the participant business data and
business service objects.
The SessionFacade is implemented as a session bean. The SessionFacade
manages the relationships between numerous BusinessObjects and
provides a higher level abstraction to the client.
It not only enforces reusable application architecture design but also
provides many advantages, including reduced network overhead,
centralized security management and transaction control, coarse-grained
abstraction of business data and service objects, and reduced coupling
between clients and business objects.
The Session Façade design pattern uses an enterprise session bean as a
façade, which abstracts the underlying business object interactions and
provides a uniform, coarse-grained service access layer to clients.
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----------------------------------------------------------------------------------------------------------------------------
113. Logger Level
DEBUG, INFO, WARN , ERROR, FATAL
// Log logger = LogFactory.getLog(getClass());
// Logger logger = Logger.getLogger(Logging.class.getName());
Logger logger = Logger.getLogger("com.foo.Bar");
logger.setLevel(Level.INFO)
log4j speak, an output destination is called an appender
Console Appender
File Appender – Daily Rolling File Appender, Rolling File Appender
Socket Appender
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LOG4J.xml
----------------
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration>
<appender name="Stdout"
class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-d [%t] %-5p
%c - %m%n"/>
</layout>
</appender>
<appender name="FA"
class="org.apache.log4j.DailyRollingFileAppender">
<param name="DatePattern" value="'.'dd-MM-yyyy-HHmm"/>
<param name="File" value="D:/jakarta-tomcat5.0.27/webapps/Classic1.0.0/WEB-INF/classic.log" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-d [%t] %-5p
%c - %m%n"/>
</layout>
</appender>
<appender name="clientLOG"
class="org.apache.log4j.DailyRollingFileAppender">
<param name="File" value="D:/jakarta-tomcat5.0.27/webapps/Classic1.0.0/WEB-INF/clientLOG.log"/>
<param name="DatePattern" value="'.'yyyy-MM-dd"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%d{yyyyMM-dd HH:mm:ss} %-5p (%F:%L)[%t] - %m%n"/>
</layout>
</appender>
<logger name="classic.stringarray" additivity="false">
<level value="DEBUG"/>
<appender-ref ref="FA"/>
</logger>
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<logger name="classic" additivity="false">
<level value="DEBUG"/>
<appender-ref ref="clientLOG"/>
</logger>
<root>
<priority value="debug"/>
<appender-ref ref="FA"/>
<appender-ref ref="Stdout"/>
</root>
</log4j:configuration>
---------------------------------------------------------------------------------------------------------------------------114. Sequence Diagram Vs Collaboration Diagram
Collaboration Diagram
Represents Interaction of objects and relationship.
Sequential Diagram
Represents flow of events in a sequential order
Both Express similar information but shows in a different ways.
It allows to
114.
find flow of controls,
115.
identify the objects, classes, interactions and
116.
help to validate the architecture
----------------------------------------------------------------------------------------------------------------------------
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115. Poor Practices in Software Development






Inaccurate understanding of End user needs
Inability to deal with Change Requirements
Software that hard to maintain or extend
Unacceptable software performances
Poor software Quality
Untrustworthy build and release process
----------------------------------------------------------------------------------------------------------------------------
116. Software Best practices





Develop Software iteratively
Manage Requirements
Use Component based Architecture
Continuously verify software quality
Control changes to software
---------------------------------------------------------------------------------------------------------------------------117. RUP has four phases
o Inception - Scope of the project
o Elaboration – Plan project, specify features, baseline Architecture
o Construction – Build the project
o Transition – Transition the product to the End user
---------------------------------------------------------------------------------------------------------------------------118. What is Model and Object?
Model: Simplification of reality
Object: Set of Attributes and operations
Class: set of objects that share same attributes, operations,
relationships and semantics
---------------------------------------------------------------------------------------------------------------------------119. Object Orientation
Abstraction: Any model that includes most important aspect
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Encapsulation: Hides implementation details from Clients
Modularity: Logical decomposition.
Hierarchy: Ranking of Abstraction
---------------------------------------------------------------------------------------------------------------------------120.
Signature of Perform method in Action Class
public ActionForward perform(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) throws
IOException, ServletException {
121. Typical Structs-Config . xml file
<struts-config>
<form-beans>
<form-bean name="generatepromotioncodeform"
type="com.fedex.chronos.mma.promotion.beans.formbean.GeneratePromotio
nCodeFB"/>
</form-beans>
<global-forwards>
<forward name="failure" path="/jsp/ErrorPage.jsp"/>
</global-forwards>
<action-mappings>
<action path="/promotioncodemain"
type="com.fedex.chronos.mma.promotion.action.PromotionCodeMainAction"
name="promotioncodemainform"
scope="session" >
<forward name="promotioncodemainjsp"
path="/jsp/PromotionCodeMain.jsp"/>
<forward name="expire"
path="/jsp/PromotionCodeMain.jsp"/>
<forward name="success"
path="/jsp/PromotionCodeMain.jsp"/>
<forward name="failure"
path="/jsp/PromotionCodeMain.jsp"/>
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<forward name="logout"
path="/jsp/PromotionCodeEntry.jsp"/>
</action>
</action-mappings>
</struts-config>
----------------------------------------------------------------------------------------------------------------------------
122. What is Polymorphism?
Hiding different implementation behind single interface
----------------------------------------------------------------------------------------------------------------------------
123.
Association
Relationship between objects connectivity
Aggregation
Relationship between whole part and its part
Generalization
Relationship between Parent and child objects
<|____________________
Dependency
Relationship between model elements where a change in one
element will cause a change in another element
o - - - -- - >
---------------------------------------------------------------------------------------------------------------------------124.
Analysis Class –
Handle primarily functional requirements. To capture early draft of the
object of the system
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Boundary Class – intermediates between interface and outside the
system
Entity Class – Key abstraction of the system
Control Class - Use case behaviors coordinator. One per use case
---------------------------------------------------------------------------------------------------------------------------125.
Activity Diagram – is used to find the activity in the use case.
It is a flow chart showing flow of control from activity to activity
------------------------------------------------------------------------------------------------------------------------126.
2 Phase Commit
Transaction Coordinator will send ‘ Prepare to Commit’ to Transaction
Manager. TM will send message to Resource Manager (RM). RM will send
back message to TM. TM will inform to TC about the readiness to commit.
TC will commit. Uncommitted Transaction will be stored in TLOG.
-------------------------------------------------------------------------------------------------------------------------
127. Architectural Pattern
Layers, Pipe and Filter, MVC and Blackboard
It provides set of Subsystems, specifies their responsibilities and includes
rules and guidelines for organizing the relationship between them.
------------------------------------------------------------------------------------------------------------------------128. Subsystem – provide interface to access its behaviour
Package – help to organize class. (Configuration Management)
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----------------------------------------------------------------------------------------------------------------------------
129.
Session Context Vs Entity Context
Session Context is the gateway for the EJB Bean to interact with the
Container. (Transaction State and Security State ). No need of user
implementation
EJB Context – where EJBean will perform call back methods to the
container. It will help bean to ascertain their status.
----------------------------------------------------------------------------------------------------------------------------
130.
Local Interface
----------------------------------------------------------------------------------------------------------------------------
131.
Life cycle of Entity Bean
Does not exist state –
Create new instance (Container will call on Bean Class)
Set entity Context (not at client call , only to increase pool
size)
Pool State
(Bean is ready – but no database storage)
ejbFind
Pool State – Read State
ejbCreate
ejbActivate
ejbLoad
Ready state –
Business method call
Ready State – Pool state
ejbRemove
Pool state – Does not exist state
Unset entity context
JVM will garbage and call finalize () method
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---------------------------------------------------------------------------------------------------------------------------132. EJB Container and Server
EJB Container – Play ground where EJBean will run. EJB object and Home
object are part of the container
EJB Server – Run time Environment for the Container
----------------------------------------------------------------------------------------------------------------------------
133. Beans in EJB



Stateful Session Bean – implements BLogic, Brule and workflow (
Shopping Cart) – handle Business Process
Stateless Session Bean – Credit Card verification
Entity Bean – represents persistent data
---------------------------------------------------------------------------------------------------------------------------134.
 Home Object Vs EJB Object
EJB Object

EJB Object – it exposes every business method that the bean itself
exposes (it is between client and bean). It delegates all client
request to beans.


Client code deals with EJB object and never with beans directly
Client cannot instantiate an EJB object directly
Home Object




To acquire reference to the EJB object. Client will ask from EJB
object factory (Home object – according to EJB Spec)
Create EJB object
Find existing EJB object
Remove EJB object
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---------------------------------------------------------------------------------------------------------------------------135. EjbPostCreate – container will call this method when bean instance is
associated with EJB object
 pass bean instance reference to other.
 Initialize the values
 Reset Transaction values
----------------------------------------------------------------------------------------------------------------------------
Gap Gemini Interview on 21 nov 2004) - SELECTED
Exception Handling
MVC MV2 Architecture
Struts Architecture
Design Pattern
DB Form
Synchronizations
Primary Key
Session Synchronization
Front Controller
Object methods
---------------------------------------------------------------------------------------------------------------------------136. Java.lang.Object has following methods
Class Object is the root of the class hierarchy. Every class has Object as a super
class. All objects, including arrays, implement the methods of this class.
Clone()
Equals()
Finalize()
getClass()
hashCode()
notify()
notifyAll()
wait()
toString()
----------------------------------------------------------------------------------------------------------------------------
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137.. List list = Collections.synchronizedList(new ArrayList(...));
Set s = Collections.synchronizedSet(new HashSet(...));
----------------------------------------------------------------------------------------------------------------------------
138.
hashCode – converting to primitive type
---------------------------------------------------------------------------------------------------------------------------139.
Why Struts?



Model 2 – MVC
Session Façade
Front Controller











JSP Model 2 Architecture
MVC
Internalization
Rich JSP Tag
Based on JSP, Servlet, XML and Java
Supports Different model implementation (Java Bean, EJB)
JSP, XSL, XSLT
Exception Handling
Validation
Tiles
---------------------------------------------------------------------------------------------------------------------------140.
Action Servlet and Request Processor?
Action Servlet – handle request, automatically populate java bean, handle
Locale and Content Type
Request Processor – which Action should be invoked
----------------------------------------------------------------------------------------------------------------------------
141. What is SssionSynchronization and where it is used?
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SessionSynchronization is implemented by session bean for Container to
callback and notify
this session bean about state of a transaction and callback methods such as
afterBegin(),
afterCompletion() and beforeCompletion() methods are used for this purpose.

afterBegin() - a new transaction has started and all the business methods
invoked, shall be
within this transaction boundary.
 afterCompletion(Boolean committed) tells the session bean that either
the transaction is
successfully executed (true)or roll backed (false).
 beforeCompletion() - whether a transaction is about to be committed.
142. MVC1, MVC2
MVC1 - combines controller and View together
MVC2 or Model 2 - seperates them out.
---------------------------------------------------------------------------------------------------------------------------143. Front Controller
While the Front Controller pattern suggests centralizing the handling of all
requests, it does not limit the number of handlers in the system, as does a
Singleton. An application may use multiple controllers in a system, each mapping
to a set of distinct services.
The controller provides a centralized entry point that controls and manages Web
request handling. By centralizing decision points and controls, the controller also
helps reduce the amount of Java code, called scriptlets, embedded in the
JavaServer Pages (JSP) page.
Centralizing control in the controller and reducing business logic in the view
promotes code reuse across requests. It is a preferable approach to the
alternative-embedding code in multiple views-because that approach may lead to
a more error-prone, reuse-by-copy- and-paste environment.
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Typically, a controller coordinates with a dispatcher component. Dispatchers are
responsible for view management and navigation. Thus, a dispatcher chooses
the next view for the user and vectors control to the resource. Dispatchers may
be encapsulated within the controller directly or can be extracted into a separate
component.
144. Action Errors ( Struts)
ActionErrors errors = null;
errors = new ActionErrors();
errors.add(ActionErrors.GLOBAL_ERROR, new
ActionError(PromotionCodeConstants.ERROR_CODE_90001, "Your current
session has been expired. Please login again."));
saveErrors(request, errors);
ActionErrors actionErrors = null;
Iterator iterator = null;
String errorMessage = null;
actionErrors = (ActionErrors)request.getAttribute(Action.ERROR_KEY);
if(actionErrors != null && !actionErrors.empty()){
out.println("<br><font color='Red'><b>");
iterator = actionErrors.get();
while (iterator.hasNext()) {
ActionError actionError = (ActionError )iterator.next();
errorMessage = (String)(actionError.getValues())[0];
out.println(" - " + errorMessage + "</font><br>");
}
}
---------------------------------------------------------------------------------------------------------------------------145.
Implicit Objects


config
Out
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


pageContext
page
exception




request
response
application
session
----------------------------------------------------------------------------------------------------------------------------
146.
javax.servlet
Interface SingleThreadModel
a. Ensures that servlets handle only one request at a time
b. This interface has no methods
c. Session attributes and static variables can still be accessed by
multiple requests on
Multiple threads at the same time, even when SingleThreadModel servlets
are used
----------------------------------------------------------------------------------------------------------------------------
147.
In JSP
isThreadSafe = true (Multiple request at one time)
---------------------------------------------------------------------------------------------------------------------------148. Action include Vs Directive Include
<jsp:include page=”” flues=”true”/>  Load Dynamic or Static pages
 Can’t set cookies and Set Headers
 Not Parsed
 It will include file during Request processing Time
<%@ include file=”header.jsp” %>  Evaluated at JSP Translation Time or Compilation Time
 Only Static page
 Parsed
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---------------------------------------------------------------------------------------------------------------------------149. Byte Code
All Java programs are compiled into class files, which contain bytecodes, the
machine language of the Java
virtual machine.
---------------------------------------------------------------------------------------------------------------------------150. Cloneable Interface
public class Clona implements Cloneable {
public void get(){
System.out.println("Hi " + getClass().getName());
}
public static void main(String ss[]) throws CloneNotSupportedException{
Clona c1 = new Clona();
c1.get();
System.out.println(" Say What " + (c1.clone() == c1) ); //FALSE
System.out.println(" Say What " + (c1.clone().getClass() ==
c1.getClass()) ); // TRUE
System.out.println(" Say What " + (c1.clone().equals(c1))); // FALSE
}
}
---------------------------------------------------------------------------------------------------------------------------151.
URL Rewriting Example
< a href = “ /mydir/mypage.jsp”> Click here <a>
Can be re-written as
< a href = <%=response.encodeURL(“ /mydir/mypage.jsp“) %> Click here
<a>
Response.sendRedirect(“ /mydir/mypage.jsp”);
Can be re-written as
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Response.sendRedirect( response.encodeRedirectUrL(“
/mydir/mypage.jsp”));
----------------------------------------------------------------------------------------------------------------------------
152. JSP Scope Types

Page Scope

Request Scope - Object is distinct for every client request

Session Scope - Object is distinct for every client request and
available as long as
session is valid

Application Scope - All client access same object
- Object exist for every client request
---------------------------------------------------------------------------------------------------------------------------153.
 Session Tracking
There are 2 common ways of passing session keys from server to client and
back.
Cookies – which used default
URL rewriting – if Cookies are disabled or not supported




URL rewriting –
URL encoded with Session Key during Server response.
Session key can carry from one server to another
Back button or different page which is not part of session, leads to session
key lost
Session key will be included only in jsp or Servlet not in HTML or
XML static pages
--------------------------------------------------------------------------------------------------------------------------154.
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Static Variable , Transient variable, Session Attribute can’t be
serialized and can’t be synchronized.
--------------------------------------------------------------------------------------------------------------------------155. Action Servlet , Action Form, Action Class, Request Processor (
Struts )
o Action Servlet per web Application (Automatically populate Java
Bean, Handle Content Type, Locale)and
o Request Processor (Invoke proper Action instance) are FRAME
WORK PROVIDED
o Action class is part of Controller not Model
o DYNAMIC ACTION FORM –
Define action form in Struts-Config.xml
o ActionForm –
 provides ability to validate the user input,
 Captures user data from the HTTP Request
 Stores data temporarily
 Extends org.apache.struts.action.ActionForm



Struts-config.xml
Web.xml Add servlet Element,
Servlet Mapping Element,
Tag Lib Elements
156.

Struts Includes Pre-built Action Classes





Forward Action
Dispatch Action
LookupDispatch Action
Include Action
Swtich Action
Struts supports EJB MODEL, CORBA, JAVA BEANS
---------------------------------------------------------------------------------------------------------------------------
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157.
Overiding Concepts
class AAA{
public void getAAA(){
System.out.println("AAA");
}
public class Clona extends AAA{
public void getAAA(){
System.out.println("Clona");
super.getAAA();
}
public static void main(String ss[]) {
AAA c = new AAA();
c.getAAA();
}
}
Output ::: AAA
=================
class AAA{
AAA(){
System.out.println("AAA constructor");
}
void getAAA(){
System.out.println("AAA");
}
}
public class Clona extends AAA{
Clona(){
System.out.println("clona constructor");
}
public void getAAA(){
System.out.println("Clona");
super.getAAA(); // super is non-static variable
}
public static void main(String ss[]) {
AAA c = new Clona(); // Parent object = new Child()
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c.getAAA();
}
}
Output :::
AAA Constructor
Clona Constructor
Clona
AAA
---------------------------------------------------------------------------------------------------------------------------
158. Extended Parent classes constructor are invoked first (Hierarchically)
, when child class instantiated
Main.java
-------------class Main {
Main(){
System.out.println("Main Constructor");
}
void getAAA(){
System.out.println("Main");
}
}
AAA.java
-------------class AAA extends Main{
AAA(){
System.out.println("AAA Constructor");
}
void getAAA(){
System.out.println("AAA");
super.getAAA();
}
}
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Clona.java
--------------public class Clona extends AAA{
Clona(){
System.out.println("Clona Constructor");
}
public void getAAA(){
System.out.println("Clona11");
super.getAAA();
}
public static void main(String ss[]) {
Clona c = new Clona(); // Line 11
c.getAAA();
}
}
Output
Main Constructor
AAA Constructor
Clona Constructor
Clona11
AAA
Main
// Even though Clona instantiated (at Line 11), Constructors of Main,
AAA and Cloan classes are invoked
Ofirst
---------------------------------------------------------------------------------------------------------------------------
159.
Super and this variable ( Core Java )




Super – is non static variable
Super – is used to call Parent method
This – is used to call constructor of a class from a constructor
This – denotes class variable in order to distinguish from passing
argument or variable
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---------------------------------------------------------------------------------------------------------------------------
160.
What are Directives in JSP (JSP)
1.
Serves as messages to JSP container from
JSP
Have scope to JSP file
2.



Page ,
Include
and Taglib
<%@ page language=”” import = “” %>
<%@ import file=”” %>
<%@ taglib uri=”” prefix=”” %>
--------------------------------------------------------------------------------------------------------------------------161.



What are Scripting Elements ? ( JSP)
Declaration
Scriptlets
Expression
---------------------------------------------------------------------------------------------------------------------------
162.
What are Standard Actions? (JSP)

Runtime behavior of the JSP



<jsp:useBean>
<jsp:setProperty>
<jsp:getProperty>
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



<jsp:param>
<jsp:include> - at run time, it will load static or dynamic page
<jsp:forward> - it will forward the request to next page
<jsp:plugin> - it will generate client browser specific HTML
---------------------------------------------------------------------------------------------------------------------------
163.



What is implicit objects? (JSP)
Implicit objects do not need to be declared
Available only in scriptlet or expressions not available in declarations
Implicit objects are only available in _jspService () method of the
generated servlet.
--------------------------------------------------------------------------------------------------------------------------164.



Life cycle of JSP ( JSP)
Page will be initialized by invoking jspInit () method
_jspService() method is for processing the request which comes from JSP
and response is taken by the container from JSP and pass back to the
client
jspDestroy() method is invoked when JSP is destroyed by the server
NOTE
165. JSP page is executed by JSP Engine or container , which is
installed in Web server or Application Server
--------------------------------------------------------------------------------------------------------------------------166.
What is Element Data in JSP?
Elements which are processed on the Server
a.
b.
c.
d.
Stand. Action
Directives
Declaration
Scriptlet
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e. Expression
---------------------------------------------------------------------------------------------------------------------------
167. (Synchronization)
http://www.cs.umd.edu/class/spring2002/cmsc433-0201/Lectures/javapart7.pdf








Synchronized in methods and statement
All objects can be locked
Only one thread can hold lock on a object
A method can be synchronized
Add synchronized modifier before return type
For a static synchronized method locks the class object
Synchronize access to share data
Don’t hold a lock on more than one object at time – could cause
DEADLOCK
Notify() – thread resume to start
Join() - wait for a thread to die
Wait() - release the lock and adds Thread to wait and suspends
thread
--------------------------------------------------------------------------------------------------------------------------168.
What is a Thread?
a. All the threads share the same memory space
b. Run concurrently in multiprocessor
Eg – WEB BROWER
c. One thread for I/O Operation
d. One thread for download the file
e. One thread for rendering web pages
---------------------------------------------------------------------------------------------------------------------------
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169.





Extending Class Thread ( Core Java)
Extend java.lang.Thread for Class to be Thread Class
Supply public void run() method
Start a thread by invoking the start() method
When thread starts, executes run() method
When run() returns, thread is finished / dead
Simple thread methods()
 Start()
 IsAlive()
 SetPriority()
 Join()
Simple static thread methods()
 Yield()
 Sleep()
 CurrentThread()
http://www.cs.umd.edu/class/spring2002/cmsc433-0201/Lectures/javapart6.pdf
--------------------------------------------------------------------------------------------------------------------------170.
Extending Class Thread ( Core Java)
Daemon Thread which is running countinuously in background
You can set a thread as daemon thread using the method
setDaemon(boolean). That will run continuously in the background. If there are
no other threads running in the application then the main thread will stop the
daemon thread and exits the application
--------------------------------------------------------------------------------------------------------------------------171.


Anonymous Class ( Core Java)
A type of inner class that has no name.
It does not use the keywords class, implements or extends
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These anonymous inner classes can access the static and instance variables of
the enclosing outer class.

WindowAdapter is a anonymous class
---------------------------------------------------------------------------------------------------------------------------
172.
Class which extends Thread class
public class MyClass extends Thread{
String messg;
MyClass(String str){
messg = str;
start();
}
public void run(){
System.out.println("[ " + messg);
try{
Thread.sleep(100000);
}catch(InterruptedException excep){}
System.out.println("] ");
}
public static void main(String ss[]){
new MyClass("Say Hello111");
new MyClass("Say Hello222");
new MyClass("Say Hello333");
}
}
--------------------------------------------------------------------------------------------------------------------------HP Singapore Interview Q on 23rd Nov 2004




BMP v CMP
Trasaction Attributes
EJB object V Home Object
Local interface
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---------------------------------------------------------------------------------------------------------------------------
173.
Class which implements Runnable Interface
public class Runna implements Runnable {
String str;
Runna(String str){
this.str = str;
}
public void run(){
for( int i = 0; i < 5 ; i++){
System.out.println("[ "+ str + " " + i);
try{
Thread.sleep(1000);
}catch(Exception excep){}
System.out.println("] ");
}
}
public static void main(String ss[]){
Thread t1 = new Thread(new Runna("hi"));
Thread t2 = new Thread(new Runna("wi"));
t1.start();
t2.start();
}
}
NOTE
174. Servlet is a platform independent. It is hosted in JSP/Servlet
Container.
---------------------------------------------------------------------------------------------------------------------------
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175.
Servlet Architecture
2 Packages make up the servlet architecture :


javax.servlet and
javax.servlet.http
javax.servlet.Servlet , javax.servlet.ServletConfig, java.io.Serializable are
interfaces implemented by javax.servlet.GenericServlet
javax.servlet.Servlet interface has
 init()
 service()
 getServletConfig()
 destroy()
 getServletInfo
javax.servlet.ServletConfig interface has
 getServletContext()
 getInitParameter()
 getInitParameterNames()
javax.servlet.GenericServlet interface has
 init()
 service()
 getServletConfig()
 destroy()
 getServletInfo
 getServletContext()
 getInitParameter()
 getInitParameterNames()
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javax.servlet.HttpServlet interface has
 service()
 getLastModified()
 doDelete()
 doPut()
 doGet()
 doPost()
 doOptions()
 doTrace()
--------------------------------------------------------------------------------------------------------------------------176.
Life cycle of servlet
 Init() – initialize the servlet
 Service() – handle client request and responds back
 Destroy() – performs clean up
---------------------------------------------------------------------------------------------------------------------------
NOTE
177. Service method is a abstract method in Generic servlet but it
is not in HttpServlet.
---------------------------------------------------------------------------------------------------------------------------
178.



Implicit Objects
Available to use in all jsp documents.
Parsed by JSP Engine
Inserted in to the Generated Servlet ( _jspService() method)
----------------------------------------------------------------------------------------------------------------------------
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179. <jsp:forward> - Standard Action enables the JSP engine
to execute a runtime dispatch of the current request to another
resources.
----------------------------------------------------------------------------------------------------------------------------
180.
JSP Error Handling
<%@ page errorPage=”xy.jsp” %>
<%
If(true){
Throw new Exception(“An exception occurred”);
}
%>
Xy.jsp
<%@ page isErrorPage=”true” %>
Error is : <%= exception.getMessage() %> has been reported
---------------------------------------------------------------------------------------------------------------------------181.



Using Servlet to Retrieve HTTP Data
public String ServletRequest.getParameter(String name);
public Enumeration ServletRequest.getParameterNames();
public String [] ServletRequest.getParameterValues(String name);
---------------------------------------------------------------------------------------------------------------------------182. Resource Bundle
ResourceBundle.getBundle will automatically look for the appropriate
properties file and create a PropertyResourceBundle that refers to it.
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The Java 2 platform provides two subclasses of ResourceBundle,


ListResourceBundle and
PropertyResourceBundle, - that provide a fairly simple way to create
resources.



ListResourceBundle manages its resource as a List of key/value pairs.
PropertyResourceBundle uses a properties file to manage its
resources.
Example for ResourceBundle
import java.util.*;
public class ResourceBundleX {
public ResourceBundleX(){
try {
String baseName = "MyResources";
ResourceBundle rb;
rb = ResourceBundle.getBundle(baseName,new Locale("telugu"));
System.out.println(" value is " +rb.getString("hello"));
} catch(Exception excep){
excep.printStackTrace();
}
}
public static void main(String ss[]){
new ResourceBundleX();
}
}
MyResources_telugu.properties
hello=Namaste
bye=ellosthe
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----------------------------------------------------------------------------------------------------------------------183.
Normalization
----------------------------------------------------------------------------------------------------------------------184. Life Cycle and Design patter
-----------------------------------------------------------------------------------------------------------------------
185.
XML
----------------------------------------------------------------------------------------------------------------------186.
EJB Tutorial
http://www.javaperformancetuning.com/tips/j2ee_ejb.shtml
http://www.jguru.com/faq/topicindex.jsp?topic=EJ
B
----------------------------------------------------------------------------------------------------------------------189. What is Scalability ?
...scalable..." An application is scalable if the system that hosts it can be
expanded or upgraded to support a higher client load, without significant
modification to the software. Scalable does not necessarily mean 'high
performance,' despite a common belief that this is the case. EJB applications
support scalability because they lend themselves to distribution; they support
high performance because they allow the sharing of resources and minimize
overheads, as we shall see.
EJB run in a framework that supports distribution, load sharing, fault
tolerance, security, and transaction management. To their clients they 'look
like' ordinary Java objects, and can be used similarly.
--------------------------------------------------------------------------------------190. What is ear file
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An .ear file is an "Enterprise Archive" file. The file has the same format as a
regular .jar file (which is the same as ZIP, incidentally). The .ear file contains
everything necessary to deploy an enterprise application on an application
server. It contains both the .war (Web Archive) file containing the web
component of the application as well as the .jar file. In addition there are
some deployment descriptor files in XML.
http://java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/Overview.fm.html
contains additional information.
----------------------------------------------------------------------------------------------------------------------
191. Why CMP is better than BMP?
Use CMP except in specific cases when BMP is necessary: fields use stored
procedures; persistence is not simple JDBC (e.g. JDO); One bean maps to
multiple tables; non-standard SQL is used.

CMP can make many optimizations: optimal locking; optimistic
transactions; efficient lazy loading; efficiently combining multiple queries to
the same table (i.e. multiple beans of the same type can be handled
together); optimized multi-row deletion to handle deletion of beans and
their dependents.
http://www.javaperformancetuning.com/tips/j2ee_ejb.shtml#REF13
----------------------------------------------------------------------------------------------------------------------
192. Stateful to Stateless Bean
:



Stateless session beans are much more efficient than stateful session
beans.
Stateless session bean have no state. Most containers have pools of
stateless beans. Each stateless bean instance can serve multiplw clients,
so the bean pool can be kept small, and doesn't need to change in size
avoiding the main pooling overheads.
A separate stateful bean instance must exist for every client, making bean
pools larger and more variable in size.
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
[Article discusses how to move a stateful bean implementation to stateless
bean implementtaion].
http://www.javaperformancetuning.com/tips/j2ee_ejb.shtml#REF13
----------------------------------------------------------------------------------------------------------------------
193. EJB performance tips
EJB calls are expensive. A method call from the client could cover all the
following: get Home reference from the NamingService (one network round trip);
get EJB reference (one or two network roundtrips plus remote creation and
initialization of Home and EJB objects); call method and return value on EJB
object (two or more network rountrips: client-server and [mutliple] server-db;
several costly services used such as transactions, persistence, security, etc;
multiple serializations and deserializations).













If you don't need EJB services for an object, use a plain Java object and
not an EJB object.
Use Local interfaces (from EJB2.0) if you deploy both EJB Client and EJB
in the same JVM. (For EJB1.1 based applications, some vendors provide
pass-by-reference EJB implementations that work like Local interfaces).
Wrap multiple entity beans in a session bean to change multiple EJB
remote calls into one session bean remote call and several local calls
(pattern called SessionFacade).
Change multiple remote method calls into one remote method call with all
the data combined into a parameter object.
Control serialization by modifying unnecessary data variables with
'transient' key word to avoid unnecessary data transfer over network.
Cache EJBHome references to avoid JNDI lookup overhead (pattern
called ServiceLocator).
Declare non-transactional methods of session beans with 'NotSupported'
or 'Never' transaction attributes (in the ejb-jar.xml deployment descriptor
file).
Transactions should span the minimum time possible as transactions lock
database rows.
Set the transaction time-out (in the ejb-jar.xml deployment descriptor file).
Use clustering for scalability.
Tune the EJB Server thread count.
Use the HttpSession object rather than a Stateful session bean to
maintain client state.
Use the ECperf benchmark to help differentiate EJB server performances.
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




















Tune the Stateless session beans pool size to minimize the creation and
destruction of beans.
Use the setSessionContext() or ejbCreate() method to cache bean specific
resources. Release acquired resources in the ejbRemove() method.
Tune the Stateful session beans cache size to and time-out minimize
activations and passivations.
Allow stateful session beans to be removed from the container cache by
explicitly using the remove() method in the client.
Tune the entity beans pool size to minimize the creation and destruction of
beans.
Tune the entity beans cache size to minimize the activation and
passivation of beans (and associated database calls).
Use the setEntityContext() method to cache bean specific resources and
release them from the unSetEntityContext() method.
Use Lazy loading to avoid unnecessary pre-loading of child data.
Choose the lowest cost transaction isolation level that avoids corrupting
the data. Transaction levels in increasing cost are:
TRANSACTION_READ_UNCOMMITED,
TRANSACTION_READ_COMMITED,
TRANSACTION_REPEATABLE_READ,
TRANSACTION_SERIALIZABLE.
Use the lowest cost locking available from the database that is consistent
with any transaction.
Create read-only entity beans for read only operations.
Use a dirty flag where supported by the EJB server to avoid writing
unchanged EJBs to the database.
Commit the data after the transaction completes rather than after each
method call (where supported by EJB server).
Do bulk updates to reduce database calls.
Use CMP rather than BMP to utilize built-in performance optimization
facilities of CMP.
Use ejbHome() methods for global operations (from EJB2.0).
Tune the connection pool size to minimize the creation and destruction of
database connections.
Use JDBC directly rather than using entity beans when dealing with large
amounts of data such as searching a large database.
Combine business logic with the entity bean that holds the data needed
for that logic to process.
Tune the Message driven beans pool size to optimize the concurrent
processing of messages.
Use the setMesssageDrivenContext() or ejbCreate() method to cache
bean specific resources, and release those resources from the
ejbRemove() method.
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---------------------------------------------------------------------------------------------------------------------194. Pattern performance tips
The ServiceLocator/EJBHomeFactory Pattern reduces the expensive JNDI
lookup process by caching EJBHome objects.






The SessionFacade Pattern reduces network calls by combining accesses
to multiple Entity beans into one access to the facade object.
The MessageFacade/ServiceActivator Pattern moves method calls into a
separate object which can execute asynchronously.
The ValueObject Pattern combines remote data into one serializable
object, thus reducing the number of network transfers required to access
multiple items of remote data.
The ValueObjectFactory/ValueObjectAssembler Pattern combines remote
data from multiple remote objects into one serializable object, thus
reducing the number of network transfers required to access multiple
items of remote data.
The ValueListHandler Pattern: avoids using multiple Entity beans to
access the database, using Data Access Objects which explicitly query
the database; and returns the data to the client in batches (which can be
terminated) rather than in one big chunk, according to the Page-by-Page
Iterator pattern.
The CompositeEntity Pattern reduces the number of actual entity beans
by wrapping multiple java objects (which could otherwise be Entity beans)
into one Entity bean.
---------------------------------------------------------------------------------------------------------------------195. Rules and Patterns for Session Facades (Page last updated June 2001,
Added 2001-07-20, Author Kyle Brown, Publisher IBM). Tips:

Use the Facade pattern, and specifically Value objects, to transfer all the
subset of data needed from an entity bean in one transfer.
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----------------------------------------------------------------------------------------------------------------------
196. EJB performance tips (Page last updated December 2001, Added 2001-1226, Author Krishna Kothapalli and Raghava Kothapalli, Publisher JavaPro). Tips:











Design coarse-grained EJB remote interfaces to reduce the number of
network calls required.
Combine remote method calls into one call, and combine the data
required for the calls into one transfer.
Reduce the number of JNDI lookups: cache the home handles.
Use session bean wrapper for returning multiple data rows from an entity
bean, rather than returning one row at a time.
Use session beans for database batch operations, entity beans typically
operate only one row at a time.
Use container-managed persistence (CMP) rather than bean-managed
persistence (BMP).
Use entity beans when only a few rows are required for the entity, and
when rows need to be frequently updated.
Use the lowest impact isolation (transaction) level consistent with
maintaining data coherency. Highest impact down:
TRANSACTION_SERIALIZABLE,
TRANSACTION_REPEATABLE_READ,
TRANSACTION_READ_COMMITED,
TRANSACTION_READ_UNCOMMITED.
Correctly simulate the production environment to tune the application, and
use profiling and other monitroing tools to identify bottlenecks.
Tune the underlying system, e.g. TCP/IP parameters, file limits,
connection pool parameters, EJB pools sizes, thread counts, number of
JVMs, JVM heap size, shared pool sizes, buffer sizes, indexes, SQL
queries, keep/alive parameters, connection backlogs.
Use clustering to meet higher loads or consider upgrading the hardware.
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----------------------------------------------------------------------------------------------------------------------
197. Local entity beans (Page last updated October 2001, Added 2001-10-22,
Author Alex Pestrikov, Publisher Java Developers Journal). Tips:



Local entity beans do not need to be marshalled, and do not incur any
marshalling overhead for method calls either: parameters are passed by
reference.
Local entity beans are an optimization for beans which it is known will be
on the same JVM with their callers.
Facade objects (wrappers) allow local entity beans to be called remotely.
This pattern incurs very little overhead for remote calls, while at the same
time optimizing local calls between local beans which can use local calls.
---------------------------------------------------------------------------------------------------------------------198. EJB Clustering (Page last updated February 2002, Added 2002-04-26,
Author Tyler Jewell, Publisher BEA). Tips:

Four locations that can provide clustering logic for an EJB are: the JNDI
naming server where the home stub is bound, the container, the home
stub, and the remote stub.
---------------------------------------------------------------------------------------------------------------------199.

Clustering should allow failover if a machine/process crashes. For stateful
sessions, this requires state replication.
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
To support distributed sessions, make sure: all session referenced objects
are serializable; store session state changes in a central repository.
---------------------------------------------------------------------------------------------------------------------.
HTTP sessions vs. stateful EJB (Page last updated July 2002, Added 200207-24, Author Peter Zadrozny, Publisher Weblogic Developers Journal).
Tips:


The comparative costs of storing data in an HTTP session object are
roughly the same as storing the same data in a stateful session
bean.
Failure to remove an EJB that should have been removed (from the
HTTP session) carries a very high performance price: the EJB will be
passivated which is a very expensive operation.
---------------------------------------------------------------------------------------------------------------------201.
Optimizing entity beans (Page last updated May 2001, Added 2001-05-21,
Author Akara Sucharitakul, Publisher Sun). Tips:




Use container-managed persistence when you can. An efficient container
can avoid database writes when no state has changed, and reduce reads
by retrieving records at the same time as find() is called.
Minimize database access in ejbStores. Use a "dirty" flag to avoid writing
tee bean unless it has been changed.
Always cache references obtained from lookups and find calls. Always
define these references as instance variables and look them up in the
setEntityContext (method setSessionContext for session beans).
Avoid deadlocks. Note that the sequence of ejbStore calls is not defined,
so the developer has no control over the access/locking sequence to
database records.
---------------------------------------------------------------------------------------------------------------------202.
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EJB 2.0 Container-Managed Persistence provides local interfaces which can
avoid the performance overheads of remote interfaces
---------------------------------------------------------------------------------------------------------------------203.
Avoid stateful sessions for Performance Tuning
---------------------------------------------------------------------------------------------------------------------204.
Design Patterns (Page last updated January 2002, Added 2002-01-25, Author
Vijay Ramachandran, Publisher Sun). Tips:










[Article discusses several design patterns: Model-View-Controller, Front
Controller, Session Facade, Data Access Object].
Use the Front Controller pattern to channel all client requests through a
single decision point, which allows the application to be balanced at
runtime.
Use a Session Facade to provide a simple interface to a complex
subsystem of enterprise beans, and to reduce network communication
requirements.
Use Data Access Objects to decouple the business logic from the data
access logic, allowing data access optimizations to be decoupled from
other types of optimizations.
Use the Data Access Object pattern to decouple business logic from data
access logic, allowing for optimizations to be made in how data is
managed.
Use the Fast-Lane Reader pattern to accelerate read-only data access by
not using enterprise beans.
Use the Front Controller pattern to centralize incoming client requests,
allowing optimizations to be made in aggregating the resulting view.
Use the Page-by-Page Iterator pattern to efficiently access a large, remote
list by retrieving its elements one sublist of value objects at a time.
Use the Session Facade pattern to provide a unified, workflow-oriented
interface to a set of enterprise beans, thus minimizing client calls to server
EJBs.
Use the Value Object pattern to efficiently transfer remote, fine-grained
data by sending a coarse-grained view of the data.
----------------------------------------------------------------------------------------------------------------------
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205.
J2EE Performance tuning (Page last updated October 2001, Added 2001-10-22,
Author James McGovern, Publisher Java Developers Journal). Tips:
Always access entity beans from session beans.
If only using an entity bean for data access, use JDBC directly instead.
Use read-only in the deployment descriptor.
Cache access to EJB homes.
Use local entity beans when beans are co-located in the same JVM.
Proprietary stubs can be used for caching and batching data.
Use a dedicated remote object to generate unique primary keys.
206. Abstract class can’t be instantiated like Interface
207. How many Jar files are used in EJB?
Ejb-jar.xml, weblogic-ejb-jar.xml and weblogic-cmp-rdbms-jar.xml
208. How many Jar files are used in EJB?
Ejb-jar.xml, weblogic-ejb-jar.xml and weblogic-cmp-rdbms-jar.xml
209. How can you optimize in Java
Creating object is costly
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Reuse the object
Avoid Synchronization
Use Final modifier where ever required
210. Struts is the defecto standard for MVC patten
Struts can’t access Database
Struts can’t provide Transaction, Load Balancing and Security
211. Ant is a make file based on Java and XML
212.
Final Class can’t be extended
Final Variable can’t be altered (MUST INTIALISE)
Final Method can’t be overridden in subclass
213.
Inheritance is nothing but, re-usable of methods and variables
214.
Non static variable can’t be used in side the Static Method – TRUE
A Static variable can be used in side the normal or simple Method - TRUE
215.
Use static method – WHEN you need only single UNIQUE COPY of a variable
216. EXPLICIT CASTING
WRONG
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Object obj = new Object;
String str = Obj; // WRONG
CORRECT
Object obj = new Object;
String str = (String) Obj;
217.
Resonse.sendRedirect() – Http Parameter information is lost
Request.requestDispatcher() – forward the request
Jsp:forward()– forward the request
Jsp:include()
218. What is Singleton Class
class Singla
{
private static Singla sx;
private Singla(){}
private String aa;
protected String getMe(){
aa = "ALL ARE WELCOME TO singleton";
return aa;
}
protected static synchronized Singla getSingla(){
if(sx == null){
System.out.println("SINGLE10 instance is created freshly");
sx = new Singla();
}
return sx;
}
};
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public class StringDay {
public static void main(String ss[]){
Singla sxx = Singla.getSingla();
System.out.println(" from singleton " +sxx.getMe());
}
}
219. If it is private constructor, than
1. If a class has private Constructor, than it can ‘t be instantiated from any
other class.
2. That class can’t be extended
3. Its method can be accessed by its public member methods
220 . Serialization
1. Serialized objects’s conversational state can be stored in the disk or file
2. Used for Session Replication
3. Serialization normally done for Simple persistence or Network
Communication
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4. Synchronization objects are using Serializations for load balancing
5. Session objects are serialized for Clustering
221. What is javap ?
Javap is used in dos prompt to see Java API
C:> javap java.util.Hashtable
222. java.sql.Date
Java.sql.Date = Date.valueOf(“2004-12-31”);
223. What is Normalization?
Normalization – enables to design and judge the quality of Database design
First Normalization –
Records are stored in the Table
Second Normalization –
All other attributes are fully or functionally depends on Primary Key or
Composite Primary Key
Third NormalizationThere is should not be trasnsitively interdependy on attributes
Boyce Codd’s Normalization All fields are depends on Primary Key and Primary Key is the super key.
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224. Design Pattern
Session Façade
MVC
MVC 2
Business Delegate
Front Controller
DAO
DTO
Print Out - > 225. SAX Vs DOM
XML was created so that richly structured documents could be used over the
web
Users must be able to view XML documents as quickly and easily as HTML
documents.
-legible and reasonably clear
XSL - Defines the standard stylesheet language for XML
(XLink), which allows elements to be inserted into XML documents in
order to create and describe links between resources.
XPointer), the language to be used as the basis for a fragment identifier
for any URI reference that locates a resource whose Internet media type is
one of text/xml, application/xml.
226. SAX, the Simple API for XML, is a standard interface for event-based
XML parsing,
DOM rograms to dynamically access and update the content and structure
of documents
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Accenture Questions on 28th Nov 2004 - SELECTED
1. Design your FedEx Project
2. Design and Planning Skills
3. What is DAO?
4. What is XSLT , XML and JSP?
5. Session Façade
6. Session Bean – how you used in Project
Scandent chennai, Questions on 29th Nov 2004 – NOT SELECTED
1. Functinal Points
2. Business Requirement Doc
3. System Requirment Doc
4. High Level Design
5. Lower Level Design
6. Sequence Diagram ( How will you arriave based on Use Case)
7. Dependency Class
8. Runnable Interface V Thread Class
9. Class | Interface | Abstract
10. Struts Frame Work
11. What is EJB QL and CMR
12. What are new Exceptions in EJB 2.0
13. What is Message Driven Bean
227. local home interface defines the methods that allow local clients to
create, find, and remove EJB objects, as well as home business methods
that are not specific to a bean instance
local interface provides the local client view of an EJB object. An enterprise
Bean's local interface defines the business methods callable by local clients
228.
java.lang.Runnable Interface
Runnable interface should be used if you are only planning to override the run()
method and no other Thread methods.
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Run() – Being active simply means that a thread has been started and has not
yet been stopped.
When an object implementing interface Runnable is used to create a
thread, starting the thread causes the object's run method to be called in
that separately executing thread.
Destroy() - Destroys this thread, without any cleanup.
Sleep() –Causes the currently executing thread to sleep (temporarily cease
execution)
Join() – Waits for this thread to die.
Yield() – Causes the currently executing thread object to temporarily pause and
allow other threads to execute.
Resume() – Depricated
Start() – Causes this thread to begin execution; the Java Virtual Machine calls
the run method of this thread.
Stop() – Depricated
Suspend() – Depricated
VERY IMPORTANT
Class Diagram Representation of
Aggregation, Association, Generalization and Dependency
How will you drive out Sequence Diagram?
What is Funcational Points?
What is BRD, SRS and HLD?
What is LLD?
229. Exceptions in EJB 2.0
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An AccessLocalException is thrown to indicate that the caller does not have
permission to call the method. This exception is thrown to local clients.
CreateException exception is used as a standard application-level exception to
report a failure to create an entity EJB object.
The DuplicateKeyException exception is thrown if an entity EJB object cannot
be created because an object with the same key already exists
The EJBException exception is thrown by an enterprise Bean instance to its
container to report that the invoked business method or callback method could
not be completed because of an unexpected error
The FinderException is used as a standard application-level exception to report
a failure to find the requested EJB object(s).
This NoSuchEntityException may be thrown by the bean class methods that
implement the business methods defined in the bean's component interface; and
by the ejbLoad and ejbStore methods.
(Normal Method) NoSuchObjectLocalException is thrown if an attempt is
made to invoke a method on an object that no longer exists.
(Finder Method)The ObjectNotFoundException exception is thrown by a finder
method to indicate that the specified EJB object does not exist.
The RemoveException exception is thrown at an attempt to remove an EJB
object when the enterprise Bean or the container does not allow the EJB object
to be removed.
TransactionRequiredLocalException indicates that a request carried a null
transaction context, but the target object requires an activate transaction.
This TransactionRolledbackLocalException
indicates that the transaction associated with processing of the request has been
rolled back, or marked to roll back. Thus the requested operation either could not
be performed or was not performed because further computation on behalf of the
transaction would be fruitless
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230. Exceptions Hierarchy
java.lang.Object
|
+--java.lang.Throwable
|
+--java.lang.Exception
|
+--java.lang.RuntimeException
|
+--javax.ejb.EJBException
241. Example of Dependency and Aggregation diagram
example of aggregation
-----------------------------public class Money{}
public class Wallet {
private Money money;
public Wallet(Money money) {
this.money = money;
}
}
The instance of aggregated class can be shared by many other classes. While
those classes are deleted, the instance of aggregated class won't be deleted."
hence, i create money object outside the wallet, the passed the money into the
wallet to make them "has a" relationship.
example of composite (dependency)
-------------------------------public class Heart {}
public class Human {
private Heart heart;
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private Human() {
heart = new Heart();
}
}
the instance of composited class can only be used by one other class. While that
class is deleted. The composited class will also be deleted."
the composite class is a dependency class for any classes. it leads to high
coupling. Composition is implicitly a bi-directional relationship.
Example of Generalization
Parent / Child class
http://pigseye.kennesaw.edu/~dbraun/csis4650/A&D/UML_tutorial/class.ht
m
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Nov 30, 2004
242. Mock Exam Java Questions
public class Q1 {
public static void main(String ss[]){
float f = (float)1.3; // default floatint point value is double
double d = 12.41;
byte b= 100 + 27; // max 127 NOT > 127
Byte bb = new Byte(b);
boolean bool = true; //always true or false NOT null value
char ch= 'a';
System.out.println("value of f is "+ f);
System.out.println("value of d is "+ d);
System.out.println("value of b is "+ bb.intValue());
System.out.println("value of bool is "+ bool);
System.out.println("value of ch is "+ ch);
}
}
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243. Mock Exam Java Questions
public class Q2 {
public static void main(String ss[]){
hi();
}
public void hi(){
System.out.println("welcome to q2");
}
}
Hi () method should be static since it is residing or calling from static
reference
Like :
Public static void hi(){}
244. Mock Exam Java Questions
public class Q3 {
static int a_classVariable = 1; // class variable
int b_localVariable = 2; // local variable
public static void main(String ss[]){
int c_instanceVariable = 3; //local or member variable
System.out.println("value of c is from main() " + c_instanceVariable);
//System.out.println("value of b is from classMethod() " + b_localVariable);
Q3.classMethod();
new Q3().instanceMethod();
}
public static void classMethod(){
System.out.println("value of a is from classMethod() " + a_classVariable);
// System.out.println("value of b is from classMethod() " + b_localVariable);
//non static variable can't be referenced from static context
}
public void instanceMethod(){
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int d_localvariable = 4;
System.out.println("value of a is from instanceMethod() " + a_classVariable);
System.out.println("value of b is from instanceMethod() " + b_localVariable);
}
}
245. Mock Exam Java Questions
public class Q4 {
static int a; //class variable default value is 0
public static void main(String ss[]){
int b ; //ERROR - Local variable must explicitly assign or initialize value
System.out.println(" value of a is " + b);
}
}
246. Mock Exam Java Questions
abstract class AbstraClass {
//abstract public void getMe1(); //instance method - will not work , method
names are same but modifier are different
//abstract public void getMe(); //instance method - will work , method name
are not same and child class also abstract
public static void getMe1(){
System.out.println(" welcome to AbstraClass getMe1() method ");
}
}
abstract public class Abstra extends AbstraClass{
public static void getMe1(){ //static method
System.out.println(" welcome to Child class method ");
}
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public static void main(String ss[]){
Abstra.getMe1();
}
}
247. Mock Exam Java Questions
In overriding,
Parent class or Parent Abstract class can have private method in OVER RIDING
Child class cannot have private modifier in OVER RIDING method if Parent
Abstract class or
Parent calss modifier is public or protected or packageLocal.
248. Mock Exam Java Questions
import java.io.*;
public class Mine {
public static void main(String ss[]){
Mine m = new Mine();
System.out.println(m.amethod());
}
public int amethod(){
try{
FileInputStream fis = new FileInputStream("hello.txt");
}catch(FileNotFoundException fnfe){
System.out.println("No Such file found");
return -1;
}catch(IOException ioe){
System.out.println("io exception area");
return -2;
}finally{
System.out.println("inside finally");
}
return 0;
}
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}
Out put is
No Such file found
inside finally
-1
Finally will execute irrespective of return statement at any stage ( Even
before finally block – return statement executes )
249. Mock Exam Java Questions
SUPER() – method (non static variable)
// should used inside the child constructor for calling parent constructor
// should be the first statement in side the child constructor
// super can be used to call parent class method like
ClassName.staticMethod
250. Mock Exam Java Questions
this() – method ( non static variable)
// should used inside the class or child constructor for calling child or class
constructor
// should be the first statement in side the child constructor
// it is used to distinguish passing argument with class variable (
this.parentid = parentid in setter method of java bean)
251. Mock Exam Java Questions
In OVER LOADING,
Method name should be same but different argument or modifer.
252. Mock Exam Java Questions
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Skeleton –
A server-side representation of a remote object.
The server-side skeleton is responsible for deserializing and unpacking the
request from its companion client-side stub.
submits it as a method call to be invoked on the object's implementation.
Stub A client-side representation of a remote object that is used to invoke methods on
the implementation of the remote object. Defines the interface to the remote
object implementation of an object. The stub is responsible for packaging up the
client request, serializing it, and shipping it to the companion skeleton on the
server side.
253. Mock Exam Java Questions
In OVER RIDING,
Method name should be same butt modifer can represent in hierarchy level
Like Child Class can’t have private method overriding if parent method is public
modifer
254. Mock Exam Java Questions
public class GrandParent {
GrandParent(){
System.out.println("GrandParent NULL CONSTRUCTOR ");
}
public static void getTest(){
System.out.println("getTest of GrandParent class ");
}
}
public class Parent extends GrandParent {
Parent(){
System.out.println("PARENT NULL CONSTRUCTOR ");
}
public static void getTest(){
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System.out.println("getTest of parent class ");
//GrandParent.getTest();
}
}
public class Child extends Parent {
Child(){
System.out.println("CHILD NULL CONSTRUCTOR ");
}
public static void getTest(){
System.out.println("getTest of CHILD class ");
//Parent.getTest();
}
public static void main(String ss[]){
//Child c = new Child();
//Parent c = new Child(); - ERROR
//GrandParent c = new Child(); - ASSIGN CHILD OBJECT if methods
are non-static
GrandParent c = new Parent()
ASSIGNS PARENT OBJECT, if methods are non-static in both parent and
GrandParent class (overriding)
ASSIGNS GRANDPARENT OBJECT, if methods are static in both parent
and GrandParent class (overriding)
c.getTest();
}
}
GrandParent c = new Parent()
c.getTest() if methods are static
Output is
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GrandParent NULL CONSTRUCTOR
PARENT NULL CONSTRUCTOR
getTest of GrandParent class
GrandParent c = new Parent()
c.getTest() if methods are non-static
Output is
GrandParent NULL CONSTRUCTOR
PARENT NULL CONSTRUCTOR
getTest of Parent class
Child c = new Child()
c.getTest() if methods are non-static
Output is
GrandParent NULL CONSTRUCTOR
PARENT NULL CONSTRUCTOR
CHILD NULL CONSTRUCTOR
getTest of CHILD class
255. Mock Exam Java Questions
import java.io.*;
public class FileWriterx {
public static void main(String args[]){
try{
System.out.println("....Pls Type....end to exit");
FileWriter fw = new FileWriter("c:/tt.txt",true);
BufferedReader bufferReader
= new BufferedReader(new InputStreamReader(System.in));
String a = "";
System.out.println(" File writing...." );
while (!((a = bufferReader.readLine()).equalsIgnoreCase("END"))){
fw.write(a + "\t");
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}
fw.close();
bufferReader.close();
FileReader fr = new FileReader("c:/tt.txt");
BufferedReader in
= new BufferedReader(fr);
System.out.println(" File Reading...." + in.readLine());
fr.close();
in.close();
}catch(Exception e){
e.printStackTrace();
}
}
}
From Here – NEW PRINT
DEC 1, 2004
256. Mock Exam Java Questions
If method is non-static,
Local variable can be
Final or int variable will be declared
Eg.
Public void getDemo(){
Int a = 10; //ALLOWED
Final int b = 20; // ALLOWED
Static int a = 10; //DECLARATION NOT ALLOWED, but we can use in non-static
method
Public int a= 100; // NOT ALLOWED
}
257. Mock Exam Java Questions
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A class may be abstract
If it has abstract methods or not
A class must be abstract
If a class does not want to implement abstract methods, al though it is
extending abstract class.
Note : Abstract class can’t be instantiated
258. Mock Exam Java Questions
Employee e = new Salesman();
e.getSalary();
If methods are static ( overriding method)
e.getSalary() will invoke from Employee Class
If methods are normal( overriding method)
e.getSalary() will invoke from Salesman Class
But, both cases, Constructor Employee and Constructor Salemsman () will
invoke
259. Mock Exam Java Questions
In Over-riding,
When I Should USE below method - for Calling Parent Method in OVER
RIDING
ClassName.getMethodName() - IF METHOD IS STATIC
Super.getMethodName() for calling Parent - IF METHOD IS NON – STATIC,
since super is static method.
NOTE : super should be used before RETURN statement
260. Mock Exam Java Questions
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public class Manager {
static int bonus = 5000;
public Manager() {
System.out.println("Manager() Constructor");
}
public int getSalary() {
return bonus;
}
}
public class Employee extends Manager{
private static int salary = 1000;
public Employee() {
System.out.println("Employee() Constructor");
}
public int getPrivateSalary(){
return salary;
}
public int getSalary() {
System.out.println("Employee Salary is "+ salary);
return salary;
}
}
public class Salesman extends Employee{
static int commission = 100;
public Salesman() {
System.out.println("Salesman() Constructor");
}
public int getSalary() {
VALID // int a = commission + bonus + new
Employee().getPrivateSalary();
VALID // int a = commission + bonus + getPrivateSalary();
VALID // return commission + bonus + super.getPrivateSalary();
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}
public static void main(String ss[]){
Salesman e = new Salesman();
System.out.println(e.getSalary());
}
}
261. Mock Exam Java Questions
Example of Overloading
Same method name and same argument passings type and number of
arguments in the method
public class OLoading {
public OLoading() {
System.out.println("welcome to OLoading default constructor");
}
public static void get(int a){
}
public void get(long a){
}
protected void get(long a,long b){
}
private static void get(String a,long aa,long b){
}
public static void main(String ss[]) {
}
}
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261. Mock Exam Java Questions
Example of Overriding
Same Method name and same modifier and same return type and no of
arugment passing and argument type and
public class ORidingBase {
public ORidingBase() {
}
public static void get(int a){ //over ridden method
System.out.println("welcome to Base");
}
}
public class ORiding extends ORidingBase{
public ORiding() {
}
public static final void get(int b){
System.out.println("welcome to Subclass");
ORidingBase.get(1);
}
// final is allowed in over – riding method
// final is allowed in over –ridden method
public static void main(String ss[]) {
ORiding o = new ORiding();
//ORidingBase o = new ORidingBase();
o.get(1);
}
}
262. Mock Exam Java Question
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Static
– only one instance exist for any amount of class instances
- static can be used in method and variable level
- inner class can’t have static declaration
Final
- final method can’t be over-ridden
- once created can’t be altered
- final class can’t be subclassed or can’t be inherited or can’t be extended
263. Mock Exam Java Question
Constructor –
Can be Overloaded
Defaut constructor will be created once object is created
Can’t have return type
Can’t pass void argument
Can’t have void as default return type
Can’t be overridden
264. Mock Exam Java Question
public class DConstra {
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public DConstra(int a) {
System.out.println("oNe Constructor " );
}
public static void main(String ss[]) {
DConstra d = new DConstra();
}
}
Output is ERROR since there is no default constructor
265. Mock Exam Java Question
Inner Class
public class OuterInner {
int a = 10;
final float b = 20.0f;
private static int c = 30;
String str = "raj";
char ch='c';
public OuterInner() {
System.out.println("Default Constructor OuterInner class is invoked ");
}
private class inner{
int k = 100;
public inner(){
System.out.println("Default Constructor inner is invoked ");
}
public void getMe(){
System.out.println("getMe - inner is invoked " + c);
}
public int returnK(){
return k;
}
}
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public void getMe(){
System.out.println("getMe - outer is invoked " + new inner().returnK());
}
public static void main(String ss[]) {
OuterInner o = new OuterInner();
o.getMe();
inner i = new OuterInner().new inner();
i.getMe();
}
}
Output;
Default Constructor OuterInner class is invoked
Default Constructor inner is invoked
getMe - outer is invoked 100
Default Constructor OuterInner class is invoked
Default Constructor inner is invoked
getMe - inner is invoked 30
4Dec2004
266. What is Class Loader
267. What is Design Pattern?
268. Why UML Diagram?
269. What is HLD, SRS, LLD, BRD?
270. What is Checked and Unchecked Exceptions?
271. What is Error?
272. What are JVM and What for Registers, Stack, Method Area and Heap?
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Dec 5, 2004 SUNDAY, IBM INTERVIEW – NOT SELECTED
Core Java
1. What is Interface and Abstract Class
2. Shall Interface can have inner class?
3. Shall Interface extend a Class?
4. Shall Interface extend Interface
5. Below class will compile or not
Class A {}
6. Below class will compile or not
Private or proteced class A {
}
7. What is Vector and ArrayList?
8. How will you increase ArrayList ? (ArrayList arrayList.ensureCapacity(100);)
9. Shall ArrayList will have null value
10. What is HashTable and HashMap? (both have loadfactor and rehash)
11. Shall HashTable hold null value and null key?
12. Collection, Map, List, Set are all Class or Interface?
13. Which has ordered elements ? ( List, Sorted Map, Sorted List)
14. How will you synchronize ArrayList
15. what will be the output?
Class A {
Public static void main(){….}
}
Class B extends Class A{
Public static void main(){
SOP (..)
Super.main() // ERROR since super non-static variable
This.Main() // this reserve word is non static
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}
TRY
32. Error can be catched in try-catch block
33.
Finally will execute after return or system.exit() statement
EJB
16. What are algorithm is Used in Passivation and Activation technique?
LRU, JIT for Passivation and Activation
17. why stateless has null argument in Create() method
18. what is sessionsynchronization?
19. What is Declarative and Programatic Transaction
20. What are Transaction Attributes are there?
21. Shall Entity bean will have TX_Supports Transaction Attributes?
22. what is JNDI Architechture?
23. During Transaction, shall we do passivation – NO
24. How will distinguish Stateless or Stateful during coding level
25. which is important .xml file for EAR ?
26 What EAR, JAR, WAR?
27. During Deployment, How jar will interact or communicate?
28. web.xml is important xml file for WAR
29. What is MANIFEST file
JSP and SERVLET
30. <jsp: include >and <declarative include >
31. What is Application Scope and how ill you code in servlet?
ServletContext context = getServletContext();
Context.setAttribute(“KE”,”VALUE”);
Application scope will die during Servlet/JSP container shut downs
Other scopes are : page, session , request
273. what is Multiple Inheritance?
A class which has 2 base class. Not supported in Java
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274.
Primary Storage – file system
Secondary Storage – Oracle Database
275.
Javax.servlet.http.ServletRequest request;
Javax.servlet.http.HttpSession session = request.getSession()
Returns the current session associated with this request, or if the request
does not have a session, creates new session
HttpSession session = request.getSession(true)
Returns the current session associated with this request, or if the request
does not have a session, creates new session if it is true
HttpSession session = request.getSession(false)
Returns the current session associated with this request, or if the request
does not have a session, it will not create new session
276.
Rehash() –
Increases the capacity of and internally reorganizes this hashtable, in order to
accommodate and access its entries more efficiently.
277.
Javax.servlet.http.HttpSession session;
Session. setAttribute(String name, Object value)
278. Hashtable
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Java.util.Hashtable hastable;
Hastable. put(Object key, Object value)
279. About Finally
public class Finall {
public Finall() {
System.out.println("Default Constructor - CLASS Finall is invoked ");
}
public static void main(String ss[]) {
System.out.println(" Value of return type is " + main());
}
public static int main() {
try{
throw new Exception("1");
}catch(Exception e){
// System.exit(0); return 1;
}
finally{
System.out.println("FINALLY BLOCK");
}
}
}
OUTPUT
FINALLY BLOCK
Value of return type is 1
IF System.exit(0) is used , then out put is nothing will displayed
280. What is Error Class?
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An Error is a subclass of Throwable that indicates serious problems that a
reasonable application should not try to catch. Most such errors are abnormal
conditions. The ThreadDeath error, though a "normal" condition, is also a
subclass of Error because most applications should not try to catch it.
Internal ErrorThrown to indicate some unexpected internal error has occurred in
the Java Virtual Machine.
StackOverFlowThrown when a stack overflow occurs because an application
recurses too deeply.
ClassFormatError Thrown when the Java Virtual Machine attempts to read a
class file and determines that the file is malformed or otherwise cannot be
interpreted as a class file.
281. Different Types of Inner Class
Nested Top Level
Member Class
Local Class
Anonymous Class
281. Shall Abstract Class have Constructor and inner class
abstract class AbstraClass {
static int aaa= 1;
static int getMe1(){
System.out.println(" welcome to AbstraClass getMe1() method ");
return aaa;
}
AbstraClass(){
System.out.println(" AbstraClass Constructor ");
new A().gg();
}
class A {
public void gg(){
System.out.println(" inner class is A ");
}
}
}
public class Abstra extends AbstraClass{
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static int aaa = 100;
public Abstra(){
System.out.println(" Child Constructor ");
}
static int getMe1(){ //static method
System.out.println(" welcome to Child class method ");
return aaa;
}
public static void main(String ss[]){
Abstra aaa = new Abstra();
System.out.println(aaa.getMe1());
System.out.println(aaa.aaa);
}
}
Output
AbstraClass Constructor
inner class is A
Child Constructor
welcome to Child class method
100
100
282. Shall Inner Class can be accommodated in Interface
interface Interfaca1{
class A {
public static void gg(){
System.out.println(" inner class is A ");
}
}
}
public class Interfaca implements Interfaca1{
public Interfaca(){
System.out.println(" Child Constructor ");
A.gg();
}
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void getMe1(){
System.out.println(" welcome to Child class method ");
}
public static void main(String ss[]){
Interfaca aaa = new Interfaca();
aaa.getMe1();
}
}
Output
Child Constructor
inner class is A
welcome to Child class method
283.
Class AAA{
Int a;
Static int b;
Public static void main(){
Int c = 10;
}
}
Class Variable - b
Member Variable - a
Local Variable - c
284. Tricky Program ( in Over Riding)
abstract class AbstraClass {
//abstract public void getMe1(); //instance method - will not work , method
names are same but modifier are different
//abstract public void getMe(); //instance method - will work , method name
are not same and child class also abstract
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int aaa= 1;
int getMe1(){
System.out.println(" welcome to AbstraClass getMe1() method ");
return aaa;
}
AbstraClass(){
System.out.println(" AbstraClass Constructor ");
}
}
public class Abstra extends AbstraClass{
int aaa = 100;
public Abstra(){
System.out.println(" Child Constructor ");
}
int getMe1(){ //static method
System.out.println(" welcome to Child class method ");
return aaa;
}
public static void main(String ss[]){
AbstraClass aaa = new Abstra();
System.out.println(aaa.getMe1());
System.out.println(aaa.aaa);
}
}
OutPUT:
1
100
OutPut : if all overriding methods are static
1
1
285. What is System , out and println() ?
System.out.println() – oldest way of Debugiging the statement to display in
Standard output
System is a final class
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Out is a static final field variable of PrintStream
Println() is a method in PrintStream
System.err.println
System.in
System.exit(-1)
System.setProperty()
System.load()
System.gc()
System.currentTimeMillis()
286. Tricky Program
EAR file need – application.xml
WAR file need – web.xml
287. Cookie
java.lang.Object
javax.servlet.http.Cookie
Creates a cookie, a small amount of information sent by a servlet to a Web
browser, saved by the browser, and later sent back to the server. A cookie's
value can uniquely identify a client, so cookies are commonly used for session
management.
The servlet sends cookies to the browser by using the
HttpServletResponse.addCookie(javax.servlet.http.Cookie) method, which adds
fields to HTTP response headers to send cookies to the browser, one at a time.
The browser is expected to support 20 cookies for each Web server, 300 cookies
total, and may limit cookie size to 4 KB each.
default, cookies are created using Version 0 to ensure the best interoperability.
This class supports both the Version 0 (by Netscape) and Version 1 (by RFC
2109) cookie specifications
The browser returns cookies to the servlet by adding fields to HTTP request
headers. Cookies can be retrieved from a request by using the
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HttpServletRequest.getCookies() method. Several cookies might have the same
name but different path attributes.
288. Request Header and Response Header
Javax.servlet.http.HTTPServletResponse
Javax.servlet.http.HTTPServletRequest
289.
import sun.security.util.Debug;
public class dd {
public dd() {
System.err.println("Default Constructor - CLASS dd is invoked ");
}
public static void main(String ss[]) {
int a= 100;
String s = "raja";
Debug.println("hi","venkat " + a + s);
}
}
290. System.getProperty()
import java.util.Properties;
import java.util.Enumeration;
ublic class SystemX {
public SystemX() {
Properties pros = System.getProperties();
Enumeration enum = pros.propertyNames();
while(enum.hasMoreElements()){
String str = (String)enum.nextElement();
System.out.println(" Key - Property " + str);
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System.out.println(" Value " + System.getProperty(str));
}
//System.out.println(" Value " + System.getProperty("computer.name"));
}
public static void main(String ss[]) {
SystemX x = new SystemX();
}
}
java.lang.Object
java.lang.Throwable
java.lang.Exception
javax.ejb.FinderException
javax.ejb.ObjectNotFoundException
291. ObjectNotFoundException
Only the finder methods that are declared to return a single EJB object use this
exception
Note:
Only the finder methods that are declared to return a single EJB object use this
exception. This exception should not be thrown by finder methods that return a
collection of EJB objects
292. Checked Exception
CreateException,
FinderException,
RemoveException,
ObjectNotFoundException,
DuplicateKeyException
293. EJB 2.0 Exception ( RUN TIME EXCEPTION)
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java.lang.Object
java.lang.Throwable
java.lang.Exception
java.lang.RuntimeException
javax.ejb.EJBException
javax.ejb.AccessLocalException
An AccessLocalException is thrown to indicate that the caller does not have
permission to call the method. This exception is thrown to local clients.
public class NoSuchObjectLocalException
extends EJBException
A NoSuchObjectLocalException is thrown if an attempt is made to invoke a
method on an object that no longer exists.
TransactionRequiredLocalException indicates that a request carried a null
transaction context, but the target object requires an active transaction.
TransactionRolledbackLocalException indicates that the transaction
associated with processing of the request has been rolled back
294. Why Exceptions are Class?
In order catch the reference of the Exception , we are throwing through
(new Exception()) or object.
295. FANTASTIC QUESTION about EXCEPTION and FInally
public class Finall {
public Finall() {
System.out.println("Default Constructor - CLASS Finall is invoked ");
}
public static void main(String ss[]) {
try{
System.out.println(" Value of return type is " + main());
}catch(Exception e){
System.out.println(e.getMessage());
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}
}
public static int main()throws Exception {
try{
throw new Exception("1");
}catch(Exception e){
//System.exit(0);
System.out.println(e.getMessage());
throw new Exception("2"); (like return type)
}
finally{
System.out.println("FINALLY BLOCK");
}
}
}
Output :
1
Finally Block
2
296. Exception and Finally
public class Finall {
public Finall() {
System.out.println("Default Constructor - CLASS Finall is invoked ");
}
public static void main(String ss[]) throws Exception{
try{
System.out.println(" Value of return type is " + main());
}catch(Exception e){
//e.printStackTrace();
System.out.println(e.getMessage());
throw new Exception("100");
}
}
public static int main()throws Exception {
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try{
throw new Exception("1");
}catch(Exception e){
//System.exit(0);
System.out.println(e.getMessage());
throw new Exception("2");
}
finally{
System.out.println("FINALLY BLOCK");
}
}
}
Output
1
FINALLY BLOCK
2
java.lang.Exception: 100
at Finall.main(Finall.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:3
9)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorIm
pl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:78)
Exception in thread "main"
Process finished with exit code 1
297. Difference between RemoveException and NoSuchEntityException
The RemoveException exception is thrown at an attempt to remove an EJB
object when the enterprise Bean or the container does not allow the EJB object
to be removed.
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The NoSuchEntityException exception is thrown by an Entity Bean instance to
its container to report that the invoked business method or callback method could
not be completed because of the underlying entity was removed from the
database.
Monday, Dec 13, 2004
298. Logger (Log4J)
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/**
* Created by IntelliJ IDEA.
* User: aaa1
* Date: Aug 2, 2004
* Time: 4:10:40 AM
* To change this template use File | Settings | File Templates.
*/
import org.apache.log4j.Logger;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.PropertyConfigurator;
import org.apache.log4j.xml.DOMConfigurator;
public class Hello {
public static void main(String argv[]) {
Logger logger;
logger = Logger.getLogger(Hello.class.getName());
BasicConfigurator.configure();
//PropertyConfigurator.configure(argv[0]);
logger.setLevel(Level.ERROR);
// DOMConfigurator.configure(argv[0]);
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logger.debug("Hello world.");
logger.info("What a beatiful day.");
}
}
299. Log4j.properties
# Set root logger level to DEBUG and its only appender to A1.
log4j.rootLogger=DEBUG, Stdout , RFA
# DRFA and Stdout is set to be a ConsoleAppender.
log4j.appender.Stdout=org.apache.log4j.ConsoleAppender
log4j.appender.RFA=org.apache.log4j.DailyRollingFileAppender
# DRFA and Stdout uses PatternLayout.
log4j.appender.Stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.Stdout.layout.ConversionPattern=%-d [%t] %-5p %c - %m%n
log4j.appender.RFA.layout=org.apache.log4j.PatternLayout
log4j.appender.RFA.layout.ConversionPattern=%-d [%t] %-5p %c - %m%n
# File name
log4j.appender.RFA.DatePattern='.'yyyy-MM-dd
log4j.appender.RFA.File=${user.home}/vvv.log
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#log4j.appender.RFA.MaxFileSize=1KB
# Truncate 'test' if it aleady exists.
#log4j.appender.RFA.Append=true
# Keep one backup file
#log4j.appender.R.MaxBackupIndex=2
300. Log4j.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration>
<appender name="Stdout" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-d [%t] %-5p %c %m%n"/>
</layout>
</appender>
<appender name="FA"
class="org.apache.log4j.DailyRollingFileAppender">
<param name="DatePattern" value="'.'yyyy-MM-dd-HH-mm"/>
<param name="File" value="c:/warning.log" />
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<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-d [%t] %-5p %c %m%n"/>
</layout>
</appender>
<root>
<priority value="debug"/>
<appender-ref ref="FA"/>
<appender-ref ref="Stdout"/>
</root>
</log4j:configuration>
301. build.xml
<?xml version='1.0'?>
<project name="JDK1.4.0_03 compilation " default="compile" basedir=".">
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<!-- set global properties for this build -->
<description>
simple example build file
</description>
<property name="version" value="1.8"/>
<property name="src" value="src"/>
<property name="classes" value="C:\Tomcat 4.1\webapps\PF18\WEBINF\classes"/>
<property name="include" value="C:\Tomcat 4.1\webapps\PF18\WEB-INF\lib"/>
<property name="tomcatcommon" value="C:\Tomcat 4.1\common\lib"/>
<target name="compile">
<echo message="Deleting existing class files " />
<delete dir="${classes}\com"/>
<echo message="Compiling Java Files " />
<!-- run javac to compile the source files -->
<javac srcdir="${src}" destdir="${classes}">
<classpath>
<!-- include all jar files -->
<fileset dir="${include}">
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<include name="**/*.jar"/>
</fileset>
<fileset dir="${tomcatcommon}">
<include name="**/*.jar"/>
</fileset>
</classpath>
</javac>
</target>
</project>
2.Another Build.xml (Eg) – Creating Java Doc
<?xml version='1.0'?>
<project name="PF 18 (Only Dev Env) Build" default="docs" basedir=".">
<!-- set global properties for this build -->
<description>
simple example build file
</description>
<property name="version" value="1.8"/>
<property name="src" value="src"/>
<property name="classes" value="C:\Tomcat 4.1\webapps\PF18\WEBINF\classes"/>
<property name="docs" value="C:\Tomcat 4.1\webapps\PF18\WEB-INF\docs"/>
<property name="include" value="C:\Tomcat 4.1\webapps\PF18\WEB-INF\lib"/>
<target name="init" >
<!-- Create the directory for the java docs -->
<mkdir dir="${docs}" />
</target>
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<target name="compile" depends="init">
<echo message="Deleting existing class files " />
<delete dir="${classes}\com"/>
<echo message="Deleting Java Doc files " />
<delete dir="${docs}"/>
<!-- run javac to compile the source files -->
<javac srcdir="${src}" destdir="${classes}">
<classpath>
<!-- include all jar files -->
<fileset dir="${include}">
<include name="**/*.jar"/>
</fileset>
</classpath>
</javac>
</target>
<target name="docs" depends="compile,init">
<!-- create javadocs -->
<echo message="Building a java doc for People Finder " />
<javadoc packagenames="* "
sourcepath="${src}"
defaultexcludes="yes"
destdir="${docs}"
author="true"
version="true"
use="true"
windowtitle="People Finder API Documentation Version: ${version}">
</javadoc>
</target>
</project>
3. Another Build.xml (Eg) – Creating Jar file
<?xml version='1.0'?>
<project name="Ant for Hello World Greetings!!!" default="clean" basedir=".">
<!-- set global properties for this build -->
<description>
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simple example build file
</description>
<property name="version" value="8.3"/>
<property name="src" value="src"/>
<property name="classes" value="classes"/>
<property name="lib" value="lib"/>
<property name="jarname" value="helloworld.jar"/>
<property name="backupjava" value="backupjava"/>
<property name="docs" value="docs"/>
<property name="include" value="c:\jarbank"/>
<property name="runclass" value="com.cfdev.hello.HelloWorld"/>
<target name="init" >
<!-- Create the build directory structure used by compile -->
<mkdir dir="${backupjava}" />
<mkdir dir="${classes}" />
<!-- Create the directory for the jar file -->
<mkdir dir="${lib}" />
<!-- Create the directory for the java docs -->
<mkdir dir="${docs}" />
</target>
<target name="compile" depends="init">
<!-- copy all .java files from ${src} to ${build} -->
<copy todir="${backupjava}/">
<fileset dir="${src}" includes="**/*.java"/>
<filterset>
<filter token="version" value="${version}"/>
</filterset>
</copy>
<!-- run javac to compile the source files -->
<javac srcdir="${src}" destdir="${classes}">
<classpath>
<!-- use the value of the ${classpath} property in the classpath -->
<!-- include all jar files -->
<fileset dir="${include}">
<include name="**/*.jar"/>
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</fileset>
</classpath>
</javac>
</target>
<target name="jar" depends="compile">
<!-- make a jar file -->
<jar jarfile="${lib}/${jarname}" basedir="${classes}/"/>
</target>
<target name="docs" depends="compile">
<!-- create javadocs -->
<javadoc packagenames="com.cfdev.hello.*"
sourcepath="${src}"
defaultexcludes="yes"
destdir="${docs}"
author="true"
version="true"
use="true"
windowtitle="Hello World API Documentation Version: ${version}">
</javadoc>
</target>
<target name="run" depends="jar,docs">
<!-- run the class -->
<java classname="${runclass}">
<!-- add a command line arg: <arg value="-h"/> -->
<classpath>
<!-- use the value of the ${classpath} property in the classpath -->
<!-- include all jar files -->
<!-- use the value of the ${classpath} property in the classpath -->
<pathelement path="${classes}"/>
</classpath>
</java>
</target>
<target name="clean" depends="run">
<echo message="hi am in clean" />
<delete dir="${backupjava}"/>
</target>
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</project>
3. Another Build.xml (Eg) – Running Java Prog
<?xml version='1.0'?>
<project name="XML WEBLOGS ANT" default="run" basedir=".">
<!-- set global properties for this build -->
<description>
simple example build file
</description>
<property name="version" value="8.3"/>
<property name="src" value="src2"/>
<property name="classes" value="classes"/>
<!-- <property name="classpath" value="classes"/> -->
<property name="include" value="C:\Documents and Settings\include"/>
<property name="runclass" value="Weblogs"/>
<target name="init" >
<!-- Create the build directory structure used by compile -->
<mkdir dir="${classes}" />
<!-- Create the directory for the jar file -->
<!-- Create the directory for the java docs -->
</target>
<target name="compile" depends="init">
<!-- copy all .java files from ${src} to ${build} -->
<!-- run javac to compile the source files -->
<javac srcdir="${src}" destdir="${classes}">
<classpath>
<!-- use the value of the ${classpath} property in the classpath -->
<!-- include all jar files -->
<fileset dir="${include}">
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<include name="**/*.jar"/>
</fileset>
</classpath>
</javac>
</target>
<target name="run" depends="compile">
<!-- run the class -->
<java classname="${runclass}">
<!-- add a command line arg: <arg value="-h"/> -->
<classpath>
<!-- use the value of the ${classpath} property in the classpath -->
<!-- include all jar files -->
<!-- use the value of the ${classpath} property in the classpath -->
<pathelement path="${classes}"/>
<fileset dir="${include}">
<include name="**/*.jar"/>
</fileset>
</classpath>
</java>
</target>
</project>
4. Another Build.xml (Eg) – Running Java Prog with EAR,WAR,JAR creation
and argument passing
<?xml version='1.0'?>
<project name="XML Node Reporter Build" default="run" basedir=".">
<!-- set global properties for this build -->
<description>
simple example build file
</description>
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<property name="version" value="1.8"/>
<property name="src" value="src"/>
<property name="classes" value="C:\TryXMLProClasses"/>
<property name="basedir" value="C:\Final"/>
<property name="runclass" value="NodeReporter"/>
<property name="mylog" value="c:\mylog1.xml"/>
<property name="appname" value="NodeReporterFinal"/>
<property name="war" value="${appname}.war"/>
<property name="jar" value="${appname}.jar"/>
<property name="ear" value="${appname}.ear"/>
<target name="compile" >
<mkdir dir="C:\FinalDelv"/>
<echo message="Compiling java file " />
<!-- run javac to compile the source files -->
<javac srcdir="${src}" destdir="${classes}">
<classpath>
<!-- include all jar files -->
<fileset dir="c:\jarbank">
<include name="**/*.jar"/>
</fileset>
</classpath>
</javac>
</target>
<target name="war" depends="compile">
<echo message="Running war file " />
<war warfile="${war}" webxml="web.xml">
<classes dir="${classes}">
<include name="NodeReporter.class" />
</classes>
</war>
</target>
<target name="jar" depends="compile">
<echo message="Running jar file " />
<jar jarfile="${jar}">
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<fileset dir="${classes}">
<include name="NodeReporter.class" />
</fileset>
</jar>
</target>
<target name="ear" depends="war, jar">
<echo message="Running war file " />
<ear earfile="${ear}" appxml="web.xml">
<fileset dir="${basedir}" includes="${jar}, ${war}"/>
</ear>
</target>
<target name="build-all" depends="ear">
<echo message="Running ear file " />
<copy file="${ear}" todir="C:\FinalDelv"/>
</target>
<target name="run" depends="compile, build-all" >
<echo message="Running java file " />
<!-- run javac to compile the source files -->
<java classname="${runclass}">
<arg file="c:\mylog1.xml" />
<classpath>
<pathelement path="${classes}"/>
<fileset dir="c:\jarbank">
<include name="**/*.jar"/>
</fileset>
</classpath>
</java>
</target>
</project>
5. Another Build.xml (Eg) – Running Java Prog with EAR,WAR,JAR creation
and argument passing
// Copyright © 2002 by Apple Computer, Inc., All Rights Reserved.
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//
// You may incorporate this Apple sample code into your own code
// without restriction. This Apple sample code has been provided "AS IS"
// and the responsibility for its operation is yours. You may redistribute
// this code, but you are not permitted to redistribute it as
// "Apple sample code" after having made changes.
shell> cat build.xml
<project name="hello world" default="build-all" basedir=".">
<property name="appname" value="HelloWorld"/>
<!-- change this to your local jboss installation, if different -->
<property name="dist.root" value="/usr/local/jboss/jboss-3.0.2/"/>
<property name="jboss.dist" value="${dist.root}/server/default"/>
<property name="jboss.deploy.dir" value="${jboss.dist}/deploy"/>
<!-- change this if you are not using jetty -->
<property name="servlet.jar" value="${dist.root}/jetty/lib/javax.servlet.jar"/>
<property name="src.dir" value="${basedir}/src"/>
<property name="src.docroot" value="${src}/docroot"/>
<property name="build.dir" value="${basedir}/build"/>
<property name="build.classes.dir" value="${build.dir}/classes"/>
<!-- the build path -->
<path id="build.path">
<pathelement location="${jboss.dist}/client/jboss-j2ee.jar"/>
<pathelement location="${servlet.jar}"/>
<pathelement location="${build.classes.dir}"/>
</path>
<!-- war, jar, ear files -->
<property name="war" value="${appname}.war"/>
<property name="jar" value="${appname}.jar"/>
<property name="ear" value="${appname}.ear"/>
<target name="war" depends="compile">
<war warfile="${war}" webxml="web.xml">
<classes dir="${build.classes.dir}">
<include name="${appname}Servlet.class" />
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</classes>
</war>
</target>
<target name="jar" depends="compile">
<jar jarfile="${jar}">
<fileset dir="${build.classes.dir}">
<include name="${appname}.class" />
<include name="${appname}Home.class" />
<include name="${appname}EJB.class" />
</fileset>
<metainf dir="${basedir}" includes="jboss.xml,ejb-jar.xml"/>
</jar>
</target>
<target name="ear" depends="war, jar">
<ear earfile="${appname}.ear" appxml="application.xml">
<fileset dir="${basedir}" includes="${jar}, ${war}"/>
</ear>
</target>
<!-- compilation options -->
<target name="compile">
<mkdir dir="${build.classes.dir}"/>
<javac srcdir="${src.dir}"
destdir="${build.classes.dir}"
debug="on"
deprecation="on"
classpathref="build.path"
optimize="off"
includes="*"
/>
</target>
<!-- build all, and copy to the jboss/deploy directory -->
<target name="build-all" depends="ear">
<copy file="${ear}" todir="${jboss.deploy.dir}"/>
</target>
</project>
302. Object Serialization
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Only for Object specific not for class specific.
Any non-transient variable and non-static members
Members means Variable and methods
Two Interfaces used for Object Serialization
ObjectInput extends DataInput
ObjectOutput extends DataOutput
Implementing Classes
ObjectInputStream
ObjectOutputStream
Methods used are
WriteObject and ReadObject
304. JVM is 32 bit address
Stack – store paramenters of methods
Heap – :Live java objects
Method area – bytecode
Garbage collected heap – greating new objects and garbage collected
305. Reference Variable or Reference Object or Object Reference
ClassA classObj ; //classObj is object reference
306. Static, final and private methods and constructor () can’t be overridden
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307. Synchronization
Method Synchronization (Class-specific if static method)
Block Level Synchronization
Kat era SYSTEMS, BANGALORE ( 2 Dec 2004) – SELECTED
1. What is checked and unchecked Exceptions?
2. How classes are not overlapping in the Application instances
3. EJB2.0 Exceptions
4. Class Loader
5. JVM
6. FINALLY AND FINALIZE
7. INTERFACE AND ABSTRACT CLASS
8. session failover
9. Stateful Vs HTTP Session
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WIPRO TECHNOLOGIES, BANGALORE ( 11 Dec 2004) - SELECTED
1. What is component Diagram
2. How localization implemented in Struts
3. Session Replication and Load Balancing (What is clustering)
4. SAX, DOM, JDOM
5. How will you create clustering in WEBLOGIC
6. When will session replicate in CLUSTERING
7. Logic Diagram
8. Sequential Diagram V Collaborations Diagram (now Communication Diagram)
Both are Use Case Specific. Represents in different view
SD – illustrates the behaviour of the class objects
CD – object interaction and relationship
9. What is Activity Diagram ( Object Sepecific- like DFD but you have
Synchronization)
10. What is State Diagram
11. What are the major challenges in Software Development Cycle
12. What is Architechtural Diagram ?
Security , Transaction Management, Component Based
13. When Stateful , Stateless, Entity Beans used in Project
14. How will you setup client interaction ( Client CON CALL)
15. JSF – Java Server Faces
16. What is Business Deligate Pattern
17. What is Session Façade
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18.
CTS, Chennai ( 14 Dec 2004) –
1. BMP v CMP
2. Vector or ArrayList
3. How will you deploy ejb files in WEBLOGIC 8.1
4. ejbActivate Vs ejbLoad
5. ejbPassivate Vs ejbStore
6. Triggers
7. PrepareStatement, Statement, CallableStatement
8. Database Design
9. Design Pattern
10. ResultSet
11. DriverManager v Datasource
12. Type of JDBC Drivers
13. JDOM v SAX v DOM
14. ejbLoad and ejbStore is not there in Stateful or Stateless, Why?
15. Which are Managing JDBC drivers?
16. What is ResultSet?
17. Bind Variables in JDBC Staements
18. Communication Diagram V Sequential Diagram
19. Static Initializers
20. String Buffer V String (String buffer is a final class)
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303. JAVA API
StringBuffer is a
* Final Class
* Thread Safe
* Mutable
* ensureCapacity – or – double the size
Strings are
* Final Class
* is constant, can’t be changed
* is not a wrapper class
* String concatenation “+” Operator
String and String Buffer are directly extends Object Class
303. Down Casting and UpCasting
Upcasting
String str=”raja”;
Object a = str;
Downcasting
Str = a;
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Example is
public class UpDown {
public UpDown() {
System.out.println("Default Constructor - CLASS UpDown is invoked ");
}
public static void main(String ss[]) {
System.out.println(" Value of a is ");
String str = "raja";
System.out.println("str is " + str);
Object obj = str;
StringBuffer sb = new StringBuffer(obj.toString());
sb.append("seth");
obj = sb;
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System.out.println("obj is " + obj);
sb = (StringBuffer)obj;
System.out.println("sb is " + sb);
}
}
304. DataSource V DataManager
Interface - Javax.sql.DataSource (involves in ConnectionPooling,
Distributed Transaction)
javax.sql.DataSource datasource= (javax.sql.DataSource)
initContext.lookup ("MYDSJNDI");
connect = datasource.getConnection();
An object that implements the DataSource interface will typically be registered
with a naming service based on the JavaTM Naming and Directory (JNDI) API.
1. produces a standard Connection object
2. Produces a Connection object that will automatically participate in connection
pooling. This implementation works with a middle-tier connection pooling
manager.
3. produces a Connection object that may be used for distributed transactions
and almost always participates in connection pooling. This implementation works
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with a middle-tier transaction manager and almost always with a connection
pooling manager.
4. With a basic implementation, the connection obtained through a DataSource
object is identical to a connection obtained through the DriverManager facility.
5. DataSource object has properties that can be modified when necessary. For
example, if the data source is moved to a different server, the property for the
server can be changed. The benefit is that because the data source's properties
can be changed, any code accessing that data source does not need to be
change
6. It will look up for the binded object in the JNDI for getting data base
connection. But Driver Manager will register the driver for getting the connection
DRIVER MANAGER
Java.sql.DriverManager (interface)
DriverManager.registerDriver(new oracle.jdbc.OracleDriver())
When the method getConnection is called, the DriverManager will attempt to
locate a suitable driver from amongst those loaded at initialization and those
loaded explicitly using the same classloader as the current applet or application.
Additional Points
Class.forName("my.sql.Driver"); // another way of loading driver – EXPLICIT
LOADING
To work with Datasource , we need weblogic.jar if WEBLOGIC 8.1 (Server
Specific)
To work with DriverManager, we need classes12.jar or ojdbc14.jar (Database
Specific)
305. Drivers available in Oracle 9i
These are the driver versions in the 9.0.1 release:
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- JDBC OCI Driver 9.0.1
Client-side JDBC driver for use on a machine where OCI 9.0.1 is
installed.
- JDBC Thin Driver 9.0.1
100% Java client-side JDBC driver for use in Java applets and
applications.
- JDBC Thin Server-side Driver 9.0.1
JDBC driver for use by Java Stored Procedures or by Java CORBA
objects running in Oracle 9.0.1. This driver is typically used
in a middle tier server.
- JDBC Server-side Internal Driver 9.0.1
Server-side JDBC driver for use by Java Stored procedures or by
Java CORBA objects running in Oracle 9.0.1. This driver used to
be called the "JDBC Kprb Driver".
For complete documentation, please refer to "JDBC Developer's Guide
and Reference".
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306. Type of Drivers available in JDBC 2.0
Type 1: JDBC – ODBC Bridge Driver –
This Driver Connects Java Program to Microsoft ODBC data source.
Development Purpose.
Type 2: Native API – Partly Java Driver
This Driver enables JDBC to use Database Specific API to access database.
Type 3: JDBC – NET – Pure Java Driver
This Driver translates JDBC request to Network Protocol and Server translates
the database request into a database specific protocol
Type 4: Native Protocol pure Java Driver
Java Program can connect directly to ta Database. Translates JDBC request to
Database specific / Network Protocol.
307. LDAP Programming (Search, Update, Delete, Modify)
import javax.naming.*;
import javax.naming.directory.*;
import java.util.Hashtable;
import java.util.Enumeration;
class DomainCon
{
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//user id credential
private static final String userId =
"uid=vishnu,cn=peoplefinder,ou=hp,dc=unicenter";
private static String userPwd= "vishnu";
//directory manager credential
private static final String dmId = "cn=Directory Manager";
private static final String dmPwd = "password";
//administrator credential
private static final String adminId =
"admin,ou=administrators,ou=topologymanagement,o=netscaperoot";
private static final String adminPwd = "admin";
//destroy dn, create dn, search dn, modify dn
private static final String destroy_DN =
"uid=usa,cn=peoplefinder,ou=hp,dc=unicenter";
private static final String create_DN =
"uid=sri1,cn=peoplefinder,ou=hp,dc=unicenter";
private static final String modify_DN =
"uid=vishnu,cn=peoplefinder,ou=hp,dc=unicenter";
public static void main(String args[])
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{
DomainCon dc = new DomainCon();
/* Connection from LDAP */
//System.out.println(" LDAP Connection Status is " +
dc.getLDAPConnection());
/* Destory DN or Subcontext */
//System.out.println(" destorySubContext status is " +
dc.getDestroySubcontext());
/* Create Subcontext */
//System.out.println(" createSubContext status is " +
dc.getCreateSubcontext());
/* Modify Subcontext */
//System.out.println(" modify SubContext status is " +
dc.getModifySubcontext());
/* Search Subcontext */
dc.getSearchSubcontext();
}
private void getSearchSubcontext() {
try{
DirContext dc =
(InitialDirContext)getInitialDirContext();
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//Attributes attrs = new BasicAttributes();
//Attribute sn = new BasicAttribute("sn","vas");
//attrs.put(sn);
String str1[] =
{"uid","sn","cn","telephoneNumber","mail","fax","userpassword","givenna
me"};
SearchControls scont = new SearchControls();
scont.setSearchScope(SearchControls.SUBTREE_SCOPE);
scont.setReturningAttributes(str1);
NamingEnumeration na =
dc.search("dc=unicenter","(uid=venkat)",scont);
while(na.hasMore()){
// System.out.println("tt");
SearchResult sr = (SearchResult)na.next();
if(sr.getName().indexOf("uid=") != -1){
String uid =
sr.getName().substring(sr.getName().indexOf("uid=")+4,sr.getName().index
Of(","));
System.out.println(" U I D is " + uid);
String cnn =
sr.getName().substring(sr.getName().indexOf("cn=")+3,sr.getName().lastInd
exOf(","));
System.out.println(" C N N is " + cnn);
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String ouu =
sr.getName().substring(sr.getName().lastIndexOf("=")+1);
System.out.println(" O U U is " + ouu);
}
System.out.println(" DN is " + sr.getName());
Attributes attrsFetched = sr.getAttributes();
if(attrsFetched == null){
System.out.println(" No attributes");
continue;
}
NamingEnumeration na1 = attrsFetched.getAll();
while(na1.hasMore()){
Attribute attr = (Attribute)na1.next();
String id = attr.getID();
//System.out.println("id " + id);
Enumeration na2 = attr.getAll();
while(na2.hasMoreElements()){
System.out.println( "Attribute {{ " + id + " }} value is " +
na2.nextElement());
}
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}
}
na.close();
}catch(Exception e){
e.printStackTrace();
}
}
private boolean getModifySubcontext() {
boolean modifySubcontextFlag = false;
try{
//Modify attribute using BasicAttributes Class
DirContext dc =
(InitialDirContext)getInitialDirContext();
Attributes attrs = new BasicAttributes();
Attribute mail = new BasicAttribute("mail","gdddg@gg.com",true);
attrs.put(mail);
dc.modifyAttributes(modify_DN,2,attrs);
//Modify attribute using ModificationItem Class
//Very important - Modification array should be equal to no. of
attribute
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// 1 - add new attribute value
//2 - modify existing attribute value
//3 - delete existing attribute value
// we can't create / delete attribute object - it is part of LDAP
implementation
/* BasicAttribute givenName = new
BasicAttribute("mail","fff@hp.com");
ModificationItem modifyItem[] = new ModificationItem[1];
modifyItem[0] = new ModificationItem(2,givenName);
//System.out.println( "modifyItems.length " +
modifyItem[0].getAttribute());
dc.modifyAttributes(modify_DN,modifyItem);
*/
modifySubcontextFlag = true;
dc.close();
//idc.close();
}catch(Exception e){
modifySubcontextFlag = false;
e.printStackTrace();
}
return modifySubcontextFlag;
}
private boolean getCreateSubcontext() {
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boolean createSubcontextStatusFlag = false;
try{
DirContext dc=(InitialDirContext)getInitialDirContext();
Attributes attrs = new BasicAttributes();
Attribute objectClassAttr = new BasicAttribute("objectClass",true);
objectClassAttr.add("top");
objectClassAttr.add("person");
objectClassAttr.add("organizationalPerson");
objectClassAttr.add("inetorgperson");
// we can create new object class
objectClassAttr.add("hpproject");
Attribute sn = new BasicAttribute("sn","venkatesh",true);
Attribute cn = new BasicAttribute("cn","devi venaktesh",true);
Attribute fax = new
BasicAttribute("facsimileTelephoneNumber","123",true);
Attribute phone = new
BasicAttribute("telephoneNumber","3333",true);
Attribute givenName = new
BasicAttribute("givenName","devi",true);
Attribute userPassword = new
BasicAttribute("userPassword","devi",true);
Attribute uid = new BasicAttribute("uid","devi",true);
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Attribute mail = new BasicAttribute("mail","devi",true); //update
later
Attribute creatorsName = new
BasicAttribute("creatorsName","devi",true);
Attribute title = new BasicAttribute("title","PF1.8
Enhancement",true);
// we can't create / delete attribute object - it is rule of LDAP
implementation
//Attribute title2 = new BasicAttribute("title2","PF1.8
Enhancement",true);
attrs.put(sn);
attrs.put(cn);
attrs.put(fax);
attrs.put(phone);
attrs.put(givenName);
attrs.put(userPassword);
attrs.put(uid);
attrs.put(mail);
attrs.put(creatorsName);
attrs.put(title);
//attrs.put(title2);
attrs.put(objectClassAttr);
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/*attrs.put("givenName","kriti");
attrs.put("sn","kriti");
attrs.put("cn","kriti");
attrs.put("uid","kriti");
attrs.put("userpassword","kriti");
attrs.put("mail","kriti");
//attrs.put("phonenumber","kriti");
*/
dc.createSubcontext(create_DN,attrs);
dc.close();
createSubcontextStatusFlag = true;
}catch(Exception e){
createSubcontextStatusFlag = false;
e.printStackTrace();
}
return createSubcontextStatusFlag;
}
private boolean getDestroySubcontext(){
boolean destroySubcontextStatusFlag = false;
try{
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InitialDirContext idc=(InitialDirContext)getInitialDirContext();
idc.destroySubcontext(destroy_DN);
destroySubcontextStatusFlag = true;
idc.close();
}catch(Exception e){
destroySubcontextStatusFlag = false;
e.printStackTrace();
}
return destroySubcontextStatusFlag;
}
private boolean getLDAPConnection(){
boolean LDAPConnectionStatusFlag = false;
try{
InitialDirContext idc=(InitialDirContext)getInitialDirContext();
DirContext dc =
(DirContext)idc.lookup(userId);
LDAPConnectionStatusFlag = true;
idc.close();
dc.close();
}catch(Exception e){
LDAPConnectionStatusFlag = false;
e.printStackTrace();
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}
return LDAPConnectionStatusFlag;
}
private InitialDirContext getInitialDirContext(){
Hashtable env= new Hashtable(11);
InitialDirContext ctx = null;
try
{
env.put(Context.SECURITY_AUTHENTICATION,"none");
env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.ldap.LdapCtxFactory");
env.put(Context.PROVIDER_URL,"ldap://venkatesh.unicenter:57176");
env.put(Context.SECURITY_PRINCIPAL,adminId);//User
env.put(Context.SECURITY_CREDENTIALS,adminPwd);//Password
//env.put("java.naming.ldap.version", "2");
//env.put("com.sun.jndi.ldap.connect.pool", "true");
ctx = new InitialDirContext(env);
}
catch(Exception e)
{
System.err.println("Problem getting attribute: " + e);
}
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return ctx;
}
}
308. SASL and SSL
309. java.util.Collection
310. java.sql.Statement, PreparedStatement, CallableStatement
Statement (Super Interface for all Statement )
Statement object used for executing a static SQL statement and returning the
results it produces.
By Default, only one ResultSet object per Statement object can be open at the
same time.
All execution methods in the Statement interface implicitly close a statment's
current ResultSet object if an open one exists.
Statement st = connection.createsStatement();
St.executeQuery(“Select * from tablename”)
PreparedStatement (BATCH UP the SQL STATEMENTS )
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An object that represents a precompiled SQL statement.
A SQL statement is precompiled and stored in a PreparedStatement object. This
object can then be used to efficiently execute this statement multiple times.
It will bind Variables as in Paramenter
PreparedStatement pstmt = con.prepareStatement("UPDATE EMPLOYEES
SET SALARY = ? WHERE ID = ?");
pstmt.setBigDecimal(1, 153833.00)
pstmt.setInt(2, 110592)
CallableStatement
The interface used to execute SQL stored procedures.
It will bind Variables as in Paramenter
It will return one or more ResultSet object
CallableStatement cs = connect.prepareCall("{call vbankpro(?,?)}");
cs.setString(1,"1");
cs.registerOutParameter(2,Types.FLOAT);
cs.executeUpdate();
System.out.println("" + cs.getDouble(2));
Additional Points
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Java.sql.Result Set
A ResultSet object maintains a cursor pointing to its current row of data. Initially
the cursor is positioned before the first row. The next method moves the cursor to
the next row, and because it returns false when there are no more rows in the
ResultSet object, it can be used in a while loop to iterate through the result set.
A default ResultSet object is not updatable and has a cursor that moves forward
only. Thus, you can iterate through it only once and only from the first row to the
last row. It is possible to produce ResultSet objects that are scrollable and/or
updatable
Statement stmt = con.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
ResultSet rs = stmt.executeQuery("SELECT a, b FROM TABLE2");
// rs will be scrollable, will not show changes made by others,
// and will be updatable
rs.absolute(5); // moves the cursor to the fifth row of rs
rs.updateString("NAME", "AINSWORTH"); // updates the
// NAME column of row 5 to be AINSWORTH
rs.updateRow(); // updates the row in the data source
rs.moveToInsertRow(); // moves cursor to the insert row
rs.updateString(1, "AINSWORTH"); // updates the
// first column of the insert row to be AINSWORTH
rs.updateInt(2,35); // updates the second column to be 35
rs.updateBoolean(3, true); // updates the third column to true
rs.insertRow();
rs.moveToCurrentRow();
A ResultSet object is automatically closed when the Statement object that
generated it is closed, re-executed, or used to retrieve the next result from a
sequence of multiple results.
The number, types and properties of a ResultSet object's columns are provided
by the ResulSetMetaData object returned by the ResultSet.getMetaData method.
311. DataSource Example
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import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
import javax.rmi.PortableRemoteObject;
import java.util.Hashtable;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.Connection;
public class TestDataSource {
public static void main(String ss[]){
InitialContext initContext = null;
Hashtable hashtablex = null;
Statement stmt = null;
ResultSet rset = null;
Connection connect = null;
try{
hashtablex = new Hashtable();
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hashtablex.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WL
InitialContextFactory");
hashtablex.put(Context.PROVIDER_URL,"t3://localhost:7011");
initContext = new InitialContext(hashtablex);
javax.sql.DataSource datasource= (javax.sql.DataSource) initContext.lookup
("MYDSJNDI");
connect = datasource.getConnection();
stmt = connect.createStatement();
stmt.executeQuery("SELECT
vaccountId,vaccountBalance,vaccountType,vaccountName from vbank");
rset = stmt.getResultSet();
while(rset.next()){
System.out.println("- - - - - - - - - - - - - - ");
System.out.println("Id is
<<"+rset.getString("vaccountId")+">>");
System.out.println("Balance is
<<"+rset.getDouble("vaccountBalance")+">>");
System.out.println("vaccountType is
<<"+rset.getString("vaccountType")+">>");
System.out.println("Name is
<<"+rset.getString("vaccountName")+">>");
System.out.println("- - - - - - - - - - - - - - ");
}
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}catch(Exception excep){
try{
rset.close();
stmt.close();
connect.close();
initContext.close();
}catch(Exception excep1){
excep1.printStackTrace();
}
excep.printStackTrace();
}
}
}/* end of client */
312. Driver Manager Example
public class TestDriverManager {
public static void main(String ss[]){
InitialContext initContext = null;
Hashtable hashtablex = null;
Statement stmt = null;
ResultSet rset = null;
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Connection connect = null;
try{
// Class.forName("oracle.jdbc.driver.OracleDriver");
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
connect =
DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:GDATA","scott",
"tiger");
stmt = connect.createStatement();
stmt.executeQuery("SELECT
vaccountId,vaccountBalance,vaccountType,vaccountName from vbank");
rset = stmt.getResultSet();
while(rset.next()){
System.out.println("- - - - - - - - - - - - - - ");
System.out.println("Id is
<<"+rset.getString("vaccountId")+">>");
System.out.println("Balance is
<<"+rset.getDouble("vaccountBalance")+">>");
System.out.println("vaccountType is
<<"+rset.getString("vaccountType")+">>");
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System.out.println("Name is
<<"+rset.getString("vaccountName")+">>");
System.out.println("- - - - - - - - - - - - - - ");
}
}catch(Exception excep){
try{
rset.close();
stmt.close();
connect.close();
initContext.close();
}catch(Exception excep1){
excep1.printStackTrace();
}
excep.printStackTrace();
}
}
}
313. MQ Series with JAVA
Well, IBM provides two types of Java Bindings
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1. MQI Java Bindings
2. JMS Implementation
Down load the MQI for Java.
MQSeries
SupportPac MA88: MQSeries classes for Java and MQSeries classes for Java
Messaging
http://www14.software.ibm.com/webapp/download/product.jsp?cat=ts&s=s&id=T
DUN-49EVER&pf=&presb=&type=s&postsb=
Message Driven Bean with MQSeries JMS impl or Session beans can invoke
helper classes which actually connect to MQSeries and do a put and get
message (two famous operation on MOM)."
http://www.capitalware.biz/sample_mqseries.html#javacode
http://www14.software.ibm.com/webapp/download/product.jsp?s=p&id=TD
UN49EVER&type=b&presb=n&postsb=n&cat=&fam=&rs=&S_TACT=&S_CMP=
&q=text+to+search+for&k=any&pf=&dt=TRIAL&v=5.3&x=27&y=9
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http://www.objectinnovations.com/CourseOutlines/516.html
314. JMS
Description
Messaging is a powerful programming paradigm that makes it easier
to decouple different parts of an enterprise application. Messaging
clients work by sending messages to a message server, which is
responsible for delivering the messages to their destination. Message
delivery is asynchronous, meaning that the client can continue working
without waiting for the message to be delivered. The contents of the
message can be anything from a simple text string to a serialized Java
object or an XML document.
Java Message Service (JMS) is a standard Java Application
Programming Interface (API) from Sun Microsystems that provides a
common interface for Java programmers to invoke any messaging
services such as WebLogic's JMS Service, IBM's MQSeries, Progress
Software's SonicMQ, etc. JMS is part of Java 2 Enterprise Edition
(J2EE).
Objectives
This course teaches students the why, what, and how of the
messaging paradigm and JMS. On completion, attendees will be able
to:





Write both message consumers and providers using
WebLogic's JMS
Use transactions with JMS
Set up and deploy JMS applications in WebLogic Server 8.1
Write message-driven EJB and deploy it in WebLogic Server
8.1
Define and use JMS connection pool in WebLogic Server 8.1
Course Outline
 Understanding Messaging Paradigm and JMS
185
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JMS Message Constituents
Publish-and-Subscribe Messaging Model
Point-to-Point Messaging Model
Guaranteed Messaging, Transactions, Acknowledgments, and
Failures
JMS and EJB 2.0
Deployment Considerations
Using WebLogic JMS
JMS in a Clustered Environment
Overview of Other Popular Messaging Products
315.
Duration: 3 days
Audience
This course is designed for
architects and developers who
already have experience in Java
development.



Prerequisites
 Java
Architects
Consultants
Developers
Description
Messaging is a powerful programming paradigm that makes it easier
to decouple different parts of an enterprise application. Messaging
clients work by sending messages to a message server, which is
responsible for delivering the messages to their destination. Message
delivery is asynchronous, meaning that the client can continue working
without waiting for the message to be delivered. The contents of the
message can be anything from a simple text string to a serialized Java
object or an XML document.
Java Message Service (JMS) is a standard Java Application
Programming Interface (API) from Sun Microsystems that provides a
common interface for Java programmers to invoke any messaging
services such as WebLogic's JMS Service, IBM's WebSphere MQ,
Progress Software's SonicMQ, etc. JMS is part of Java 2 Enterprise
Edition (J2EE).
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Objectives
This course aims to teach students the why, what, and how of the
messaging paradigm and JMS. On completion, attendees will be able
to:
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Write both message consumers and providers using JMS and
IBM WebSphere MQ
Use transactions with JMS
Set up and deploy JMS applications in IBM WebSphere MQ
Course Outline
Overview of WebSphere MQ

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WebSphere MQ
Architecture
Messages in
WebSphere MQ
Objects
Queues
MQI
Introduction to Java
Messaging Services (JMS)
WebSphere MQ
Intercommunication
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WebSphere MQ Security
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Enterprise Messaging
Systems
Message-Oriented
Middleware (MOM)
Overview of JMS
Messaging Models
Sending Messages to
Remote Queue Manager
Distributed Queuing
Components
Message Channels
Transmission Queues

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Cryptography,
Encryption, Decryption,
etc.
Ciphers
Message Digest
Digital Signatures
Security Goals
Authorization
JMS Messages
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Message Header Fields
Message Properties
Message Selection
Message Body
WebSphere MQ Classes for
Java
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MQ Java and MQI
MQ Java Classes
MQ Java Interfaces
JMS Common Facilities
WebSphere MQ Connector
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Destination
ConnectionFactory
Connection
Session
MessageConsumer
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Connector
Common Connector
Framework (CCF)
Architecture
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MessageProducer
JMSException
Publish/Subscribe Model
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Connecting to Topics
Create Publisher and
Subscriber
Publish Messages
Temporary Topic
Durable Subscriber
Point-to-Point Model (PTP)
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JMS Common Facilities
in PTP Model
Queue Browser
Complete PTP Example
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CCF Interfaces
WebSphere MQ
Connector
Classes
(MQConnectionSpec,
MQCommuncation,
MQInteractionSpec
Rollback and Commit
Advanced Topics in JMS
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Guaranteed Messaging
Message
Acknowledgment
Transacted Messaging
JMS and J2EE
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Overview of J2EE
Architecture
JMS Usage in J2EE
JMS and EJB 2.0's
Message-driven Bean
317.
318. http://www.ss64.com/ora/database_c.html
319. Simple Java to PDF conversion using itext-1.1.jar file
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package com.lowagie.examples.general;
import java.io.FileOutputStream;
import java.io.IOException;
import com.lowagie.text.*;
import com.lowagie.text.pdf.PdfWriter;
/**
* Generates a simple 'Hello World' PDF file.
*
* @author blowagie
*/
public class HelloWorld {
/**
* Generates a PDF file with the text 'Hello World'
*
* @param args no arguments needed here
*/
public static void main(String[] args) {
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System.out.println("Hello World");
// step 1: creation of a document-object
Document document = new Document();
try {
// step 2:
// we create a writer that listens to the document
// and directs a PDF-stream to a file
PdfWriter.getInstance(document,
new FileOutputStream("HelloWorld.pdf"));
// step 3: we open the document
document.open();
// step 4: we add a paragraph to the document
document.add(new Paragraph("Hello World"));
} catch (DocumentException de) {
System.err.println(de.getMessage());
} catch (IOException ioe) {
System.err.println(ioe.getMessage());
}
// step 5: we close the document
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document.close();
}
}
320.
oracle learning
PL Tutorial
http://www-db.stanford.edu/~ullman/fcdb/oracle/or-plsql.html#procedures
Oracle/SQL Tutorial
http://www.db.cs.ucdavis.edu/teaching/sqltutorial/
http://oldweb.uwp.edu/academic/mis/baldwin/sqlplus.htm
http://www.oraclecoach.com/oracle9i.htm
select * from tab;
select * from user_tables;
select * from user_objects;
select * from dict;
select * from USER_OBJECTS WHERE object_type like 'P%'
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select object_name,object_type from user_objects where object_name like 'V%';
delete from user_objects where object_name like 'VB%' AND OBJECT_TYPE =
'PROCEDURE'
sho err;
show error procedure procedurename
321. URL and URLConnection
import java.net.URL;
import java.net.MalformedURLException;
import java.net.URLConnection;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.InputStreamReader;
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import java.io.File;
/**
* Created by IntelliJ IDEA.
* User: aaa
* Date: Nov 19, 2004
* Time: 11:26:50 PM
* To change this template use File | Settings | File Templates.
*/
public class URLConnect {
public static void main(String ss[]) {
try{
// URL urlpath = new
URL("http://venkatsyntel.tripod.com/mycv/VenkateshRajendranCV.com");
URL urlpath = new URL("http://localhost:7011/teststruts/Success.html");
URLConnection urlConnect = urlpath.openConnection();
InputStream inputstream = null;
inputstream = urlConnect.getInputStream();
InputStreamReader inputStreamReader= new
InputStreamReader(inputstream);
int i = inputStreamReader.read();
while( i != -1){
System.out.println("char is " + (char) i);
i = inputStreamReader.read();
}
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}catch(MalformedURLException maURLExcep){
maURLExcep.printStackTrace();
}catch(Exception excep){
excep.printStackTrace();
}
}
}
322. STATIC VARIABLE and FINAL VARIABLE in side LOCAL method
public class TestStat {
static int a ;
final int aaaa ; //Compile time error – Final variable not initialized
static String b;
static char c;
static int aa[] = new int[]{1,2};
public static void TestStat() {
final int aaaa ; //Run time error
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Static int kk; // Not possible , but static variable will be used inside static
//method or non static method
int a;
}
public static void main(String ss[]) {
TestStat t = new TestStat();
t.TestStat();
}
}
323. Loading the Property file using java.util.Properties class
import java.util.Properties;
import java.io.*;
public class PropertiesRead {
public static void main(String ss[]) {
Properties properties = new Properties();
InputStream instream;
try{
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instream = new FileInputStream(new File("C:/teststruts/WEBINF/classes/com/Test.properties"));
properties.load(instream);
}catch(FileNotFoundException fnfExcep){
fnfExcep.printStackTrace();
}catch(IOException ioExcep){
ioExcep.printStackTrace();
}
System.out.println(properties.getProperty("prompt.submit1"));
}
}
324. Using <a href=#> and <a name=#>
<html>
<head>
<title> Concepts of A href</title>
</head>
<body>
<p>
<hr width="100%">
<a name="#index">Content </a>
<p><a href="#first">CoreGroupTechnology,Trichy</a></p>
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<p><a href="#second">Syntel India Ltd, Chennai</a></p>
<p><a href="#third">Hewlett Packard India Ltd, Bangalore</a></p>
<p><a href="#fourth">WiproTechnolgy,Chennai</a></p>
<p><a href="#fifth">Projects</a></p>
</p>
<p>
<hr width="100%">
<a name="#first"></a>
<b><font famggkce="Arial">1. Core Group Technology, Trichy</font></b>
<p>
<blockquote>
My first Company. Worked from Nov ,1998 as Programmer in J2EE
Technolgy.
</blockquote>
</p>
<hr width="100%">
<a name="#second"></a>
<b><font face="Arial">2. Syntel India Ltd, Chennai</font></b>
<p>
<blockquote>
My Second Company. Worked from Sep 2000 as Programmer Analyst in J2EE
Technolgy.
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</blockquote>
</p>
<hr width="100%">
<a name="#third"></a>
<b><font face="Arial">3. Hewlett Packard India Ltd, Bangalore</font></b>
<p>
<blockquote>
My Third Company. Worked from May 2004 as Senior Software Engineer
in J2EE Technolgy.
</blockquote>
</p>
<hr width="100%">
<a name="#fourth"></a>
<b><font face="Arial">4. Wipro Technology, Chennai</font></b>
<p>
<blockquote>
My Fourth Company. Working from Jan 2005 as Module Lead in J2EE
Technolgy.
</blockquote>
</p>
<hr width="100%">
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<a name="#fifth"></a>
<b><font face="Arial">5. Projects</font></b>
<p>
<blockquote>
<ol>
<li>
Gulf Based Company projects
</li>
<li>
iPLANET based Internal Project
</li>
<li>
GMAC Client projects ( Logistics & Insurance)
</li>
<li>
HAP (Health Alliance Plan ) Client project (HealthCare)
</li>
<li>
FedEx Client projects (Logistics)
</li>
<li>
Unilever Client project (Portal)
</li>
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</ol>
</blockquote>
</p>
<a href="#index">go top</a>
</body>
<script language="JavaScript">
document.writeln("<BR><I>This page last updated: " + document.lastModified +
"</I>");
</script>
</html>
325. Using Driver …connect DB
import java.util.Hashtable;
import java.util.Properties;
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import java.sql.*;
/**
* Created by IntelliJ IDEA.
* User: aaa
* Date: Dec 17, 2004
* Time: 7:15:52 AM
* To change this template use File | Settings | File Templates.
*/
public class TestDriverManager {
public static void main(String ss[]){
InitialContext initContext = null;
Hashtable hashtablex = null;
Statement stmt = null;
ResultSet rset = null;
Connection connect = null;
Properties probs = new Properties();
probs.put("user","scott");
probs.put("password","tiger");
probs.put("server","localhost:1521:GDATA");
try{
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// Driver driver =
(Driver)Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
// connect = driver.connect("jdbc:oracle:thin:",probs);
//below line - load the driver and register driver with Register Manager
Class.forName("oracle.jdbc.driver.OracleDriver");
//below line - load the driver and register driver with Register Manager
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
connect =
DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:GDATA","scott",
"tiger");
stmt = connect.createStatement();
stmt.executeQuery("SELECT
vaccountId,vaccountBalance,vaccountType,vaccountName from vbank");
rset = stmt.getResultSet();
while(rset.next()){
System.out.println("- - - - - - - - - - - - - - ");
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System.out.println("Id is
<<"+rset.getString("vaccountId")+">>");
System.out.println("Balance is
<<"+rset.getDouble("vaccountBalance")+">>");
System.out.println("vaccountType is
<<"+rset.getString("vaccountType")+">>");
System.out.println("Name is
<<"+rset.getString("vaccountName")+">>");
System.out.println("- - - - - - - - - - - - - - ");
}
}catch(Exception excep){
try{
rset.close();
stmt.close();
connect.close();
initContext.close();
}catch(Exception excep1){
excep1.printStackTrace();
}
excep.printStackTrace();
}
}
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}
326.
public class TestStaticV {
int a ;
public void getMethod(){
a = -1;
System.out.println("value of a 1 is "+ a);
a = 1;
get();
System.out.println("value of a 2 is "+ a);
}
public void get(){
a = 1000;
System.out.println("value of a3 is "+ a);
}
public static void main(String arg[]){
//System.out.println(" hi ");
TestStaticV v = new TestStaticV();
v.getMethod();
}
}
output
value of a 1 is -1
value of a3 is 1000
value of a 2 is 1000
327.
public class TestStaticV {
int a ;
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public void getMethod(){
a = -1;
System.out.println("value of a 1 is "+ a);
a = 1;
get();
a = 33;
System.out.println("value of a 2 is "+ a);
}
public void get(){
a = 1000;
System.out.println("value of a3 is "+ a);
}
public static void main(String arg[]){
//System.out.println(" hi ");
TestStaticV v = new TestStaticV();
v.getMethod();
}
}
output
value of a 1 is -1
value of a3 is 1000
value of a 2 is 33
328. What is XSL and XSLT and XSL Processor
329. What is SAX , DOM and JAX (what are their APIs)
330. Who is creating Stub and Skeleton in EJB? And Why
331. What is Instance Pooling and Instance Passivation
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332. What is Aggregation, Association, Composition, Inheritance ,
Specialization?
Inheritance – common methods and
Specialization –
Generalization – relationship between parent and child classes
333. What is Object Model, Dynamic Model and Functional Model?
Object Model – all class diagram, Aggregation, Assocation, Composition,
Generalization and Colloboration and Sequential Diagram
Colloboration – and - Sequenctial Diagram – models the interaction of
class objects and its relationship.
But sequential talks about object messaging behaviour in chronology
order.
Dynamic Model – State Diagram (depicts dynamic part of the system flow)
Functional Model – Data Flow Diagram
334. <xsl:variable> and <xsl:if > & <xsl:value-of select=”@attribute”>
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<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<ol>
<xsl:apply-templates select="forum/message"/>
</ol>
</xsl:template>
<xsl:template match="message">
<li>
<xsl:if test="@name='EJB' or @name='ejb'">
<xsl:variable name='skill'>
<xsl:value-of select="@name"/>
</xsl:variable>
<xsl:value-of select="$skill" />
</xsl:if>
</li>
</xsl:template>
</xsl:stylesheet>
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XML
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet href="forum.xsl" type="text/xsl"?>
<forum>
<message id="1" name="java"></message>
<message id="2" name="ejb"></message>
<message id="3" name="cpp"></message>
<message id="4" name="oracle"></message>
</forum>
335. <xsl:value-of select=”element”>
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<ol>
<xsl:apply-templates select="school"/>
</ol>
</xsl:template>
<xsl:template match="school">
<xsl:value-of select="name"/> is located in
<xsl:value-of select="location"/>,
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<xsl:value-of select="state"/>
</xsl:template>
</xsl:stylesheet>
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet href="school.xsl" type="text/xsl"?>
<school>
<name>
Arivalayam
</name>
<location>
Madurai
</location>
<state>
Tamil Nadu
</state>
</school>
336. <xsl:sort>
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
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<xsl:output method="xml" />
<xsl:template match="/">
<xsl:for-each select="presidents/president">
<xsl:sort select="name/first" />
<xsl:apply-templates select="name"
/>
<hr/>
</xsl:for-each>
</xsl:template>
<xsl:template match="name">
<xsl:value-of select="first" />
<xsl:text disable-outputescaping="yes">&amp;nbsp;</xsl:text>
<xsl:value-of select="last" />
</xsl:template>
</xsl:stylesheet>
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<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="presidents.xsl"?>
<presidents>
<president>
<name>
<first>
aaa
</first>
<last>
AAA
</last>
</name>
</president>
<president>
<name>
<first>
zzz
</first>
<last>
ZZZ
</last>
</name>
</president>
<president>
<name>
<first>
bbb
</first>
<last>
BBB
</last>
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</name>
</president>
</presidents>
337. In EJB
Equals, hashcode and toString are the 3 methods required for PK class. It is
required for Container.
Container will look for PK in String format
Container will look for hashcode, since it stores Bean in Hashtable or alike
structure.
Equals for comparing the PK when Two bean has same data
338. JUnit
TestCase - A test case defines the fixture to run multiple tests
TestSuite- . It runs a collection of test cases
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339. Code Optimization in order to have Scalability
Avoid Synchronization
Avoid creating objects
Declare variables inside the method
Release the resource after every usage
Use static methods when ever u need single copy
Use Wrapper methods
Use PrepareStatement and JNDI lookup based DataSource (connection pooling)
340. Junit Sample Code
public class Sample1 extends TestCase {
int a ;
int b;
public void testEmptyCollection() {
Collection collection = new ArrayList();
assertTrue(collection.isEmpty());
}
public void testName(){
assertEquals("venus",Sample2.getName());
}
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public void testAmount(){
assertTrue(1000.0f == Sample2.getAmount());
}
public void testVariable(){
assertEquals(a,b);
}
public void setUp(){
a = 20;
b = 20;
}
public Sample1(String name) {
super(name);
}
public static Test suite() {
//return new TestSuite(Sample1.class);
//TestSuite suite= new TestSuite(Sample1.class);
TestSuite suite= new TestSuite();
suite.addTest(new Sample1("testEmptyCollection"));
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suite.addTest(new Sample1("testVariable"));
suite.addTest(new Sample1("testName"));
suite.addTest(new Sample1("testAmount"));
suite.addTest(Sample3.suite());
return suite;
}
public static void main(String ss[]) {
junit.textui.TestRunner.run(suite());
}
}
public class Sample2 {
public static String getName(){
return "venus";
}
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public static float getAmount(){
return 1000.0f;
}
}
public class Sample3 extends TestCase {
protected int a;
protected int b;
Collection collection = null;
public Sample3(String name){
super(name);
}
protected void setUp(){
collection = new ArrayList();
collection.add(new Integer(1));
}
public static Test suite(){
return new TestSuite(Sample3.class);
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}
public void testCollection(){
assertTrue(1 == collection.size());
}
public static void main(String args[]){
junit.textui.TestRunner.run(suite());
}
}
341. XML APIs
Org.jdom.
Org.w3c.dom
Org.xml.sax
Javax.xml.parser
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342.
Why Optimization?
Premature optimization is the root of all evils
A program is that it requires simply too many resources, and these resources
(memory, CPU cycles, network bandwidth, or a combination) may be limited.
Code fragments that occur multiple times throughout a program are likely to be
size-sensitive,
while code with many execution iterations may be speed-sensitive.
double x = d * (lim / max) * sx;
double y = d * (lim / max) * sy;
the common sub expression is calculated once and used for both calculations:
double depth = d * (lim / max);
double x = depth * sx;
double y = depth * sy;
for (int i = 0; i < x.length; i++)
x[i] *= Math.PI * Math.cos(y);
becomes
double picosy = Math.PI * Math.cos(y);
for (int i = 0; i < x.length; i++)
x[i] *= picosy;
343. OPTIMIZATION IN JAVA
In Java, code should be reused and inherited wherever it is applicable
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Initialize Array at Run Time
Avoid using String, Use String Buffer
Avoid Date class, which consumes more space, use Long
Declare static final variable in Interface, which will avoid redundancy in class
Avoid Run time String Concatenation
In the JDK interpreter, calling a synchronized method is typically 10 times
slower than calling an unsynchronized method. With JIT compilers, this
performance gap has increased to 50-100 times (see Java microbenchmarks).
Avoid synchronized methods if you can -- if you can't, synchronizing on methods
rather than on code blocks is slightly faster (tip and benchmarks from Doug Lea).
You should only use exceptions where you really need them--not only do they
have a high basic cost, but their presence can hurt compiler analysis
The String concatenation operator + looks innocent but involves a lot of work: a
new StringBuffer is created, the two arguments are added to it with append(), and
the final result is converted back with a toString(). This costs both space and time.
In particular, if you're appending more than one String, consider using a
StringBuffer directly instead (tip from Jason Marshall, see also space aspects in
Optimizing for Size).
Avoid Vector, Use Array
Avoid 2 dimensional Array
Use Hashtable and rehash the hashtable
Inner class object instantiation is about 2x as expensive (time-wise) as normal
object creation. If you are going to be creating a lot of inner class objects, you
may be better off making a support class in the same package and which is not
public.
Use Local variable
OPTIMIZATION
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









Reserving StringBuffer capacity
Avoiding premature object creation
Creating an efficient vector class
Designing caching into your API
The cost of synchronization
Parallel subtasks
JNI efficiency
Varying the server workload and RMI network plumbing
Using ServletOutputStream
Caching JDBC(TM) connections
344. String Buffer is Thread Safe
java.lang.StringBuffer
StringBuffer in a non-multithreaded environment (or
you at least know that nobody will be modifying the StringBuffer at the
same time you are, which is essentially a single-threaded environment)
you will want to write your own StringBuffer (I use one called
SuperStringBuffer) that does not synchronize it's methods. Calling a
synchronized method is about 4x slower than calling one that's not
synchronized).
StringBuffer b = new StringBuffer();
b.append(foo);
b.append(bar);
b.append(baz);
it's considerably faster to do it like this:
StringBuffer b = new StringBuffer();
synchronized (b)
{
b.append(foo);
b.append(bar);
b.append(baz);
}
because the former has to obtain three object locks, where as the latter
only has to obtain one.
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345. Which method should use in OPTIMIZATION
static (class) methods
These are the fastest to call, taking around 220ns.
final methods
These are somewhere between static and instance methods, taking around
300ns.
instance methods
These are a little slower, taking around 550ns.
interface methods
These are surprisingly slow, taking on the order of 750ns to call.
synchronized methods
These are by far the slowest, since an object lock has to be obtained, and
take around 1,500ns.
The moral of the story is that if you can get away with it, use static final methods,
and don't use interfaces. This is too bad, since most good OO design involves
interfaces and for the most part, static methods are only useful in "library"
classes that are just a collection on useful methods.
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From Wipro 23rd March 2005
346.
Abstract Class and Interface can’t be instantiated
Abstract class should have word “abstract” for the abstract method (which is not
implemented in abstract class itself) , not necessary for Interface.
Interface methods are relatively slow.
Interface allow public method and static final variable or constant variable
Abstract allows public or protected methods and variables
Abstract class can have constructor. It will be invoked when ever extending
class got INSTANTIATED
abstract class abstractA {
public static int a = 10;
protected int b = 100;
abstract protected void getA();
abstractA(){
System.out.println("aaaa");
}
}
public class abstract1 extends abstractA{
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public void getA(){
System.out.println("value is AA" + a);
}
public static void main(String ss[]){
abstract1 a1 = new abstract1();
a1.getA();
}
}
347. Concrete Class
A class which has method implementations and able to instantiate.
348.
You can serialize any instance of the class with the defaultWriteObject method in
ObjectOutputStream
You can deserialize any instance of the class with the defaultReadObject method in
ObjectInputStream
Default serialization can be slow, and a class might want more explicit control over the
serialization.
Customizing Serialization
customize serialization for your classes by providing two methods for it: writeObject
and readObject
transient
and static fields are not serialized or deserialized
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Particularly sensitive classes should not be serialized. To accomplish this, the object
should not implement either the Serializable or Externalizable interface.
The class should implement writeObject and readObject methods to save and restore
only the appropriate state
Externalizable Interface
Reading and Writing its content. Object state is saved in the stream.

If externally defined format is being written, the writeExternal and
readExternal methods are solely responsible for that format.
349.
Remote Method Invocation (RMI)--communication between objects via sockets
350.
When to implement Runnable vs subclassing Thread
Whenever your class has to extend another class, use Runnable.
This is particularly true when using Applets
Start - Causes this thread to begin execution; the Java Virtual Machine calls the run
method of this thread.
In most cases, the Runnable interface should be used if you are only planning to override
the run() method and no other Thread methods
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351.







Project planning, feasibility study: Establishes a high-level view of the intended project and
determines its goals.
Systems analysis, requirements definition: Refines project goals into defined functions and
operation of the intended application. Analyzes end-user information needs.
Systems design: Describes desired features and operations in detail, including screen
layouts, business rules, process diagrams, pseudocode and other documentation.
Implementation: The real code is written here.
Integration and testing: Brings all the pieces together into a special testing environment,
then checks for errors, bugs and interoperability.
Acceptance, installation, deployment: The final stage of initial development, where the
software is put into production and runs actual business.
Maintenance: What happens during the rest of the software's life: changes, correction,
additions, moves to a different computing platform and more. This, the least glamorous and
perhaps most important step of all, goes on seemingly forever
352.
A collaboration diagram describes interactions among objects in terms of
sequenced messages. Collaboration diagrams represent a combination of
information taken from class, sequence, and use case diagrams describing
both the static structure and dynamic behavior of a system.
A statechart diagram shows the behavior of classes in response to external
stimuli. This diagram models the dynamic flow of control from state to state
within a system.
An activity diagram illustrates the dynamic nature of a system by modeling the
flow of control from activity to activity. An activity represents an operation on
some class in the system that results in a change in the state of the system.
Typically, activity diagrams are used to model workflow or business processes
and internal operation. Because an activity diagram is a special kind of
statechart diagram, it uses some of the same modeling conventions.
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353. Pass reference by value
public class passbyref {
String s;
passbyref(String ss){
s = ss;
}
public static void main(String ss[]){
passbyref p = new passbyref("11");
System.out.println(" before value of s "+p.s );
foo(p);
System.out.println(" after value of s "+ p.s );
}
public static void foo(passbyref p){
p.s = "222";
}
}
354. Pass by value
public class Pass {
public static void main(String ss[]){
String bar = "bar";
foo( bar );
System.out.println( bar );
}
static void foo(String bar )
{
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bar = "foo";
}
}
355. What is Clone()
The most likely reason for making a local copy of an object is if you’re going to modify
that object and you don’t want to modify the caller’s object. If you decide that you want
to make a local copy, you simply use the clone( ) method to perform the operation
public class passbyref implements Cloneable{
String s;
passbyref(String ss){
s = ss;
}
public static void main(String ss[]) throws
CloneNotSupportedException{
passbyref p = new passbyref("11");
System.out.println(" before value of s "+p.s );
foo((passbyref)p.clone());
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System.out.println(" after value of s "+ p.s );
}
public static void foo(passbyref p){
System.out.println(" inside foo value of s "+ p.s );
p.s = "222";
}
}
356
A)
if("".equals(myString))
{
...
}
B)
if(myString.equals(""))
{
...
}
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A is best
357
http://www.jchq.net/tutorial/05_02Tut.htm
The creation of two strings with the same sequence of letters
without the use of the new keyword will create pointers to
the same String in the Java String pool. The String pool is a
way Java conserves resources. To illustrate the effect of
this
String s = "Hello";
String s2 = "Hello";
if (s==s2){
System.out.println("Equal without new operator");
}
String t = new String("Hello");
string u = new String("Hello");
if (t==u){
System.out.println("Equal with new operator");
}
From the previous objective you might expect that the first
output "Equal without new operator" would never be seen
as s and s2 are different objects, and the == operator tests
what an object points to, not its value. However because of
the way Java conserves resources by re-using identical
strings that are created without the new operator s and s2
have the same "address" and the code does output the string
"Equal without new operator"
However with the second set of strings t and u, the new
operator forces Java to create separate strings. Because the
== operator only compares the address of the object, not the
value, t and u have different addresses and thus the string
"Equal with new operator" is never seen.
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///////////////////////////////////////////////////////////////////////////////////
358.
Frame Properties
<!-- align=position
class=name
dir=(rtl,ltr) direction
frameborder=value
height=number
lang=language
id=name
longdesc=url
marginheight=number
marginwidth=number
name=name
scrolling=type
src=url
style=style
title=string
width=number -->
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Window Properties
//win = window.open("","win1","width=700, height=400, top=90, left=300,
toolbar=0, menubar=0, location=0, status=0, scrollbars=1,
resizable=0,directories=no") ;
ShowModalDialog Properties
var MyValue = window.showModalDialog("url", "arguments", "properties");
"dialogHeight: 200; resizable: no; center: yes;"
Property Value Description
center
the screen
yes/no Specifies whether or not to display the box in the center of
dialogHeight x The height (in pixels) of the box
dialogWidth
dialogLeft
screen
dialogTop
y The width (in pixels) of the box
x The distance (in pixels) from the box to the left edge of the
y The distance to the top of the screen
help
yes/no Whether or not to display the ?-button on the titlebar
resizable
yes/no Specifies if the box should be resizable by users
status
yes/no Specifies if the box should have a statusbar
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///////////////////////////////////////////////////////////////////////////////////
359.
Date currentDate = new Date();
SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yy");
String defaultDate = dateFormat.format(currentDate);
//Date Formating
String dbDate = membershipDetailsRecord[9];
if((dbDate.trim() != null) && (dbDate.indexOf("9999-01-01 00:00:00") == 1)){
//2005-06-01 00:00:00.0
SimpleDateFormat dbDateFormat = new SimpleDateFormat("yyyyMM-dd HH:mm:ss");
SimpleDateFormat indiaDateFormat = new
SimpleDateFormat("dd/MM/yyyy");
try{
Date dbDateParsed = dbDateFormat.parse(dbDate);
String formattedDate = indiaDateFormat.format(dbDateParsed);
membershipForm.setDatebox(formattedDate);
}catch(Exception ex){
ex.printStackTrace();
}
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//
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