Modern Programming Languages
(The Java Language)
Assignment No. 3
BSCS/BSIT/BSSE
Instructions for Assignment Submission
 Hand Written Assignment Submission is required
 Copy Paste Assignment will award you 0 Marks
 You are required to answer all the Questions.
 Submission Deadline is: Before or On Final MPL Paper
Question# 1
Write note on Composition vs. inheritance
Question# 2
A. Create a class with a static final field and a final field and demonstrate the difference
between the two.
B. Create a class with a blank final reference to an object. Perform the initialization of the
blank final inside all constructors. Demonstrate the guarantee that the final must be
initialized before use, and that it cannot be changed once initialized.
Question# 3
A. Create a class as abstract without including any abstract methods and verify that you
cannot create any instances of that class.
B. Create a base class with an abstract print( ) method that is overridden in a derived class.
The overridden version of the method prints the value of an int variable defined in the
derived class. At the point of definition of this variable, give it a nonzero value. In the
base-class constructor, call this method. In main( ), create an object of the derived type,
and then call its print( ) method. Explain the results.
C. Create an abstract class with no methods. Derive a class and add a method. Create a
static method that takes a reference to the base class, downcasts it to the derived class,
and calls the method. In main( ), demonstrate that it works. Now put the abstract
declaration for the method in the base class, thus eliminating the need for the downcast.
Question# 4 Write Complete Java Code for each of the followings
A. Create an interface containing three methods, in its own package. Implement the
interface in a different package.
B. Prove that all the methods in an interface are automatically public.
Question# 5
A. Define Inner Classes
B. Differentiate between downcasting and upcasting
C. Write a class named Outer that contains an inner class named Inner. Add a method to
Outer that returns an object of type Inner. In main( ), create and initialize a reference to
an Inner.
D. Create an interface with at least one method, in its own package. Create a class in a
separate package. Add a protected inner class that implements the interface. In a third
package, inherit from your class and, inside a method, return an object of the protected
inner class, upcasting to the interface during the return.
E. Create a class with a private field and a private method. Create an inner class with a
method that modifies the outer-class field and calls the outer-class method. In a second
outer-class method, create an object of the inner class and call its method, then show the
effect on the outer-class object.
F. Determine whether an outer class has access to the private elements of its inner class.
G. Create a private inner class that implements a public interface. Write a method that returns
a reference to an instance of the private inner class, upcast to the interface. Show that the
inner class is completely hidden by trying to downcast to it.
H. Write short note on anonymous classes and nested classes in java. Give Java Code example
of each of these two types
Question# 6
A. Create a generator class that produces character names (as String objects) from your
favorite movie (you can use Snow White or Star Wars as a fallback) each time you call
next( ), and loops around to the beginning of the character list when it runs out of names.
Use this generator to fill an array, an ArrayList, a LinkedList, a HashSet, a
LinkedHashSet, and a TreeSet, then print each container.
B. Create a class, then make an initialized array of objects of your class. Fill a List from your
array. Create a subset of your List by using subList( ), then remove this subset from your
List.
C. Create a Set of the vowels. Working from UniqueWords.Java, count and display the
number of vowels in each input word, and also display the total number of vowels in the
input file.
Question# 7
A. Create a class with a main( ) that throws an object of class Exception inside a try block.
Give the constructor for Exception a String argument. Catch the exception inside a catch
clause and print the String argument. Add a finally clause and print a message to prove
you were there.
B. Define an object reference and initialize it to null. Try to call a method through this
reference. Now wrap the code in a try-catch clause to catch the exception.
C. Write code to generate and catch an ArraylndexOutOfBoundsException.
D. Create your own exception class using the extends keyword. Write a constructor for this
class that takes a String argument and stores it inside the object with a String reference.
E. Write a method that displays the stored String. Create a try-catch clause to exercise
your new exception.
E. Create three new types of exceptions. Write a class with a method that throws all three. In
main( ), call the method but only use a single catch clause that will catch all three types
of exceptions.
F. Create a class with two methods, f( ) and g( ). In g( ), throw an exception of a new type
that you define. In f( ), call g( ), catch its exception and, in the catch clause, throw a
different exception (of a second type that you define). Test your code in main( )
G. Create a three-level hierarchy of exceptions. Now create a base-class A with a method that
throws an exception at the base of your hierarchy. Inherit B from A and override the
method so it throws an exception at level two of your hierarchy. Repeat by inheriting class
C from B. In main( ), create a C and upcast it to A, then call the method.
Question# 8
A. Create a class called SortedDirList with a constructor that takes a File object and builds a
sorted directory list from the files at that File. Add to this class two overloaded list( )
methods: the first produces the whole list, and the second produces the subset of the list
that matches its argument (which is a regular expression).
Question# 9 What is Java FX? Why Java FX is used? what are the advantages of using Java
FX? Create a sample calculator using Java FX
Question# 10 Answer the following Qs
a. What is Android?
b. When Android was first launched?
c. Who first launched Android?
d. What are the basic requirements of Android?
e. What is API level in Android application development?
f. What is Activity?
g. What is activity manager in Android application development?
h. What are the basic folders (Project Structure) for Android application
development?
i. What is manifesto file in Android application development?
j. Create a sample calculator in Android application development?
k. Create a sample media player application in Android application development?
l. Create a guest book in Android application development?
Question# 11:How to create a stored procedure in SQL Server?
Consider the following table
tbl_Projects (ProjectSID, ProjectTitle, ProjectSupervisor,CellNo,Email)
create a stored procedure for this table in SQL Server to insert a new Record to Database from
Java.
Question# 32: Why jTable control is used in Java?
Consider the following table
tbl_Projects (ProjectSID, ProjectTitle, ProjectSupervisor,CellNo,Email)
Suppose there are 100 Records in this table, you are required to show all the 100 Record to
jTable control using Java code. Write complete code
Self-Study : How Java Differs from C and C++
Here is a brief description of most of the major differences between C, C++ , and the Java
language. If you are a programmer familiar with either C or C++, you may will find to catch
some of the common mistakes and assumptions programmers make when using Java.
Pointers
Java does not have an explicit pointer type. Instead of pointers, all references to objects—
including variable assignments, arguments passed into methods, and array elements—are
accomplished by using implicit references. References and pointers are essentially the same thing
except that you can’t do pointer arithmetic on references (nor do you need to). Reference semantics
also enable structures such as linked lists to be created easily in Java without explicit pointers;
merely create a linked list node with variables that point to the next and the previous node. Then,
to insert items in the list, assign those variables to other node objects.
Arrays
Arrays in Java are first class objects, and references to arrays and their contents are accomplished
through explicit references rather than via point arithmetic. Array boundaries are strictly
enforced; attempting to read past the ends of an array is a compile or run-time error. As with
other objects, passing an array to a method passes a reference to the original array, so changing
the contents of that array reference changes the original array object.
Arrays of objects are arrays of references that are not automatically initialized to contain actual
objects. Using the following Java code produces an array of type MyObject with ten elements, but
that array initially contains only nulls:
MyObject arrayofobjs[] = new MyObject[10];
You must now add actual MyObject objects to that array:
for (int i; i< arrayofobjs.length. i++) {
arrayofobjs[i] = new MyObject();
Java does not support multidimensional arrays as in C and C++. In Java, you must create arrays
that contain other arrays.
Strings
Strings in C and C++ are arrays of characters, terminated by a null character (\0). To operate
on and manage strings, you treat them as you would any other array, with all the inherent
difficulties of keeping track of pointer arithmetic and being careful not to stray off the end of
the array.
Strings in Java are objects, and all methods that operate on strings can treat the string as a
complete entity. Strings are not terminated by a null, nor can you accidentally overstep the end
of a string (like arrays, string boundaries are strictly enforced).
Memory Management
All memory management in Java is automatic; memory is allocated automatically when an
object is created, and a run-time garbage collector (the “GC”) frees that memory when the object
is no longer in use. C’s malloc and free functions do not exist in Java.
To “force” an object to be freed, remove all references to that object (assign variables holding
it to null, remove it from arrays, and so on). The next time the Java GC runs, that object is
reclaimed.
Data Types
As mentioned in the early part of this book, all Java primitive data types (char, int, long, and
so on) have consistent sizes and behavior across platforms and operating systems. There are no
unsigned data types as in C and C++ (except for char, which is a 16-bit unsigned integer).
The boolean primitive data type can have two values: true or false. Boolean is not an integer,
nor can it be treated as one, although you cannot cast 0 or 1 (integers) to boolean types in Java.
Composite data types are accomplished in Java exclusively through the use of class definitions.
The struct, union, and typedef keywords have all been removed in favor of classes.
Casting between data types is much more controlled in Java; automatic casting occurs only when
there will be no loss of information. All other casts must be explicit. The primitive data types
(int, float, long, char, boolean, and so on) cannot be cast to objects or vice versa; there are
methods and special “wrapper” classes to convert values between objects and primitive types.
Operators
Operator precedence and association behaves as it does in C. Note, however, that the new
keyword (for creating a new object) binds tighter than dot notation (.), which is different
behavior from C++. In particular, note the following expression:
new foo().bar;
This expression operates as if it were written like this:
(new foo()).bar;
Operator overloading, as in C++, cannot be accomplished in Java. The , operator of C has been
deleted.
The >>> operator produces an unsigned logical right shift (remember, there are no unsigned data
types).
The + operator can be used to concatenate strings.
Control Flow
Although the if, while, for, and do statements in Java are syntactically the same as they are in
C and C++, there is one significant difference. The test expression for each control flow construct
must return an actual boolean value (true or false). In C and C++, the expression can return
an integer.
Arguments
Java does not support mechanisms for optional arguments or for variable-length argument lists
to functions as in C and C++. All method definitions must have a specific number of arguments.
Command-line arguments in Java behave differently from those in C and C++. The first element
in the argument vector (argv[0]) in C and C++ is the name of the program itself; in Java, that
first argument is the first of the additional arguments. In other words, in Java, argv[0] is argv[1]
in C and C++; there is no way to get hold of the actual name of the Java program.
Other Differences
The following other minor differences from C and C++ exist in Java:
n Java does not have a preprocessor, and as such, does not have #defines or macros.
Constants can be created by using the final modifier when declaring class and instance
variables.
n Java does not have template classes as in C++.
n Java does not include C’s const keyword or the ability to pass by const reference
explicitly.
n Java classes are singly inherited, with some multiple-inheritance features provided
through interfaces.
n All functions are implemented as methods. There are no functions that are not tied to
classes.
n The goto keyword does not exist in Java (it’s a reserved word, but currently
unimplemented). You can, however, use labeled breaks and continues to break out of
and continue executing complex switch or loop constructs.
Prepared By:
Saif ur Rehman, Assistant Professor
UIIT, PMAS Arid Agriculture University, Rawalpindi
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