Java and Project Delivery
E&CE 250
Winter 2002
http://ece.uwaterloo.ca/~rrolon/java/tutorial.ppt
http://ece.uwaterloo.ca/~rrolon/java/tutorial.pdf
Java on Polaris
• We are using the Java 2 Version 1.3 SDK
java -version
• It provides the following tools:
javac
The compiler for the Java programming language
java
The launcher for Java applications
javadoc
API document generation
jar
Creation and management of Java Archive files
jdb
The Java Debugger
appletviewer
The launcher for Java applets
Setting up
1. Log onto Polaris
2. Open the MS-DOS prompt from Windows
3. Create a ece250 directory in n:\
n:\ mkdir ece250
4. Edit n:\privexec.bat and add the lines:
set PATH=%PATH%;q:\eng\ece\jdk1.3\bin
set CLASSPATH = N:\ece250
5. Run the batch file n:\privexec.bat again
Java program: StringOperations
• Use any text editor you like
• Enter the following program:
public class StringOperations {
public static void main (String[] args) {
String str = “If there were dreams to sell, What would you buy?”;
System.out.println (“The string is: ” + str);
System.out.println (“The length is: ” + str.length());
System.out.println (“Substring 14-20: ” + str.substring(14,20));
System.out.println (“Uppercase is: ” + str.toUpperCase());
}
}
• Save the program as StringOperations.java in your
n:\ece250 directory
Compile the program
• Open the MS-DOS prompt and change your directory:
n:\> cd ece250
• Now compile the program:
n:\ece250> javac StringOperations.java
• If everything works, you’ll get no messages back
• Check to see if a StringOperations.class file has been
created. n:\ece250> dir *.class
Note: For a Java program to compile properly, the
name of the file and class defined must be the
same. Remember: file name = class name.
Run the program
• Now run the program:
n:\ece250> java StringOperations
If it works, you’ll see:
The string is: If there were dreams to sell, What would you buy?
The length is: 49
Substring 14-20: dreams
Uppercase is: IF THERE WERE DREAMS TO SELL, WHAT WOULD YOU BUY?
• If it fails, you’ll probably see:
Exception in thread “main”
java.lang.NoClassDefFoundError:
StringOperations
This will happen if you forgot to set the classpath to
include your working directory.
javadoc
http://java.sun.com/j2se/1.3/docs/tooldocs/javadoc/
• A brief introduction to javadoc:
– The purpose of this tool is to automatically generate
HTML documentation from your .java source files.
– You can run Javadoc on individual .java files, or .jar
files
– A comment must be added before the section it is
commenting
javadoc
• The documentation is created by adding special tags in
your .java files. These tags enable you to document your
source code.
• The tags start with an "at" sign (@) and are case-sensitive
(they must be typed with the lowercase letters as shown)
• Some common tags are:
@author
@version
@exception
@throws
javadoc Example
/**
* The StringOperations class represents manipulation of strings
* @author Ricardo Rolon
* @version 1.0, Sep 2001
*/
public class StringOperations {
/**
* Creates a String object.
*/
public static void main (String[] args) {
String str = “If there were dreams to sell, What would you buy?”;
System.out.println (“The string is: ” + str);
System.out.println (“The length is: “ + str.length());
System.out.println (“Substring 14-20: “+ str.substring(14,20));
System.out.println (“Uppercase is: “ + str.toUpperCase());
}
}
Javadoc -author -version StringOperations.java
Jar files
http://www.javasoft.com/j2se/1.3/docs/tooldocs/win32/jar.html
• The jar tool allows you to create archives, similar to a .zip
archive. (In fact, they are based on ZIP compression)
• There are several reasons we want to do this:
– easier to transfer (compressed files = less time over a network)
– easier to execute (all the .class files are in the .jar, makes only one
connection to the server)
– jar’s can be signed by the author (security)
– can store additional files like .html, readmes, etc.
Jar files
Example: jar
cvmf myManifestFile myJarFile *.class *.html
*.java
Where c option indicates that a jar file must be created,
v means to be Verbose
m include my own Manifest file
f put the .jar file in a separate File whose name is provided
The Java Virtual Machine needs to know which .class file in the .jar file
contains the main( ) method. To do that, create a text file with just one line:
Main-Class: <MainJavaClass>
For instance, in Project 1, if Rational.class is the class that contains main(),
then MyManifestFile should contain the following line:
Main-Class: Rational
Don’t forget to end the Main-Class line with a carriage return, otherwise jar
will not recognize it.
jdb (java debugger)
http://java.sun.com/j2se/1.3/docs/tooldocs/win32/jdb.html
•
•
•
•
•
Compile the program with the -g option (extra class info)
Start jdb java debugger
Set breakpoints
Run program
Experiment with debugger commands:
–
–
–
–
–
–
list -- Displays the source code of the line and several lines around it
locals -- List the values of local variables that are currently in use
print <item> -- Display the value of the variable, object, array
step -- Executes the next line and stops again
cont -- Continues running the program
!! -- repeats the previous debugger command.
• After debugging the program, recompile the program without
the -g option.
jdb --A debugging example
1. Compile the program: javac
2. Start the debugger:
-g StringOperations.java
jdb StrigOperations
3. Set breakpoints:
stop in StringOperations.main
stop at StringOperations:15
4. Run program: run
StringOperations
5. Extract debugging info with commands:
list, locals, print, step, cont
6. Recompile the program: javac
StringOperations.java
Free Java Tools
• JBuilder, Borland.
• VisualAge for Java, IBM.
• Forte for Java (http://www.sun.com/forte/ffj/),Sun Microsystems.
JCreator, JEditor, etc.
• No native methods!!
Keep this in mind:
We have to be able to compile it and run it on the
Java 2 SDK 1.3 platform
Vector
http://webobjects.uwaterloo.ca
• Vector is a web-based application course administration
• E&CE 250 will use Vector for the following:
– Tracking of your marks for Projects
– Electronic submission of your Projects
• Every student in this course has an account in Vector.
• Use your Polaris userid to login, and your ID # as your
initial password.
• Change your password immediately.
Submitting files with Vector
• Project 1-3
– individual submission, under studentID
• Project 4
– group submission, under groupID
[even if group of one student]
Project 1-3: Naming of .jar files
• Name the file as your numeric Student id
followed by pn where n is the project number.
(That is, just 12345678p1.jar)
• In Vector, the file name will be prep ended by
your Polaris account
• For example:
If your Polaris userid is “student1” then this will
upload the file as student1_12345678p1.jar
Project 4: Naming of .jar files
• Send email to ece250 with group membership by
signup due date (even if group of 1). You will get
your GroupID by email.
• Name the file as your GroupID followed by p4
where n is the project number. (If the GroupID is
E250G007, use E250G007p4.jar)
• In Vector, the file name will be prepended by
your GroupID
• For the above example, the file will be uploaded
as E250G007_E250G007p4.jar
Recomendations
• Please post common questions on the ECE
250 newsgroup
• You can also send us email, phone us, or
drop by during office hours
• Make sure you give yourself lots of time.