Download Java - PESIT South

USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
INTERNAL ASSESSMENT TEST – 1
Date
: 16/08/16
Subject & Code : JAVA and J2EE (10CS753)
Section
Name of faculty : Ms. Bidisha , Ms. Neeta
Time
1:00pm
1.
a
Max Marks : 50
: A,B,C
: 11:30 am to
Discuss the Object oriented properties of Java
Ans:
Object-oriented programming (OOP) is at the core of Java.
6
The Three OOP Principles:
All object-oriented programming languages provide mechanisms that help you
implement the object-oriented model. They are:
1. encapsulation,
2. inheritance, and
3. polymorphism (Explain with examples)
b
What is Java Bytecode? Explain
4
Ans:
 The key that allows Java to solve both the security and the portability problems.
 the output of a Java compiler is not executable code
 Bytecode is a highly optimized set of instructions designed to be executed by the Java
run-time system,
 which is called the Java Virtual Machine (JVM)
 JVM was designed as an interpreter for bytecode
 Translating a Java program into bytecode makes it much easier to run a program in a
wide variety of environments because only the JVM needs to be implemented for
each platform.
B.E/MBA/MCA/M.Tech
<<Semester Number>>
2. A
Write a program to explain the Inheritance properties of Java
7
USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
Ans: To inherit a class, you simply incorporate the definition of one class into another
by using the extends keyword.
Note: Variables decalred private in the super class cannot be inherited
// A simple example of inheritance.
// Create a superclass.
class A {
int i, j;
void showij() {
System.out.println("i and j: " + i + " " + j);
}
}
// Create a subclass by extending class A.
class B extends A {
int k;
void showk() {
System.out.println("k: " + k);
}
void sum() {
System.out.println("i+j+k: " + (i+j+k));
}
}
b
class SimpleInheritance {
public static void main(String args[]) {
A superOb = new A();
B subOb = new B();
// The superclass may be used by itself.
superOb.i = 10;
superOb.j = 20;
System.out.println("Contents of superOb: ");
superOb.showij();
System.out.println();
/* The subclass has access to all public members of
its superclass. */
subOb.i = 7;
subOb.j = 8;
subOb.k = 9;
System.out.println("Contents of subOb: ");
subOb.showij();
subOb.showk();
System.out.println();
System.out.println("Sum of i, j and k in subOb:");
subOb.sum();
}
}
Differentiate between Multiple Inheritance and Multilevel Inheritance
Ans: Multiple Inheritance:
One derived class can have more than one base class. Java does not support directly.
B.E/MBA/MCA/M.Tech <<Semester Number>>
3
USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
We can use the interface to experience the same.
Multilevel Inheritance:
One child class is derived from a base class which was derived from another base
class. Java supports the same.
3.
a
Explain with examples, constructors in Java
4
Ans: A constructor initializes an object immediately upon creation. It has the same
name as the class in which it resides and is syntactically similar to a method. Once
defined, the constructor is automatically called immediately after the object is created,
before the new operator completes
class Box {
double width;
double height;
double depth;
// This is the constructor for Box.
Box() {
System.out.println("Constructing Box");
width = 10;
height = 10;
depth = 10;
}
// This is the parameterized constructor for Box.
Box(double w, double h, double d) {
width = w;
height = h;
depth = d;
}
// compute and return volume
double volume() {
return width * height * depth;
}
}
class BoxDemo6 {
public static void main(String args[]) {
// declare, allocate, and initialize Box objects
Box mybox1 = new Box();
Box mybox2 = new Box(10, 20, 15);double vol;
// get volume of first box
vol = mybox1.volume();
System.out.println("Volume is " + vol);
// get volume of second box
vol = mybox2.volume();
System.out.println("Volume is " + vol);
}
}
b
What is overloading and overriding? Explain
1)
B.E/MBA/MCA/M.Tech <<Semester Number>>
6
USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
Method overloading is used to increase the readability of the program.
Method overriding is used to provide the specific implementation of the method that is
already provided by its super class.
2)
Method overloading is performed within class.
Method overriding occurs in two classes that have IS-A (inheritance) relationship.
3)
In case of method overloading, parameter must be different.
In case of method overriding, parameter must be same.
4)
Method overloading is the example of compile time polymorphism.
Method overriding is the example of run time polymorphism.
5)
In java, method overloading can't be performed by changing return type of the
method only. Return type can be same or different in method overloading. But you
must have to change the parameter.
Return type must be same or covariant in method overriding.
Detail the same using small java code.
4.
a
Write a note on the following keywords:
i)
b
3*2
Super:
1. super is used to refer immediate parent class instance variable.
2. super() is used to invoke immediate parent class constructor.
3. super is used to invoke immediate parent class method.
ii) Static:
The static keyword in java is used for memory management mainly. We can apply
java static keyword with variables, methods, blocks and nested class. The static
keyword belongs to the class than instance of the class.
The static can be:
1. variable (also known as class variable)
2. method (also known as class method)
3. block
4. nested class
B.E/MBA/MCA/M.Tech <<Semester Number>>
4
USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
What are Interfaces?
An interface is a reference type in Java, it is similar to class, it is a collection of
abstract methods. A class implements an interface, thereby inheriting the abstract
methods of the interface.
Along with abstract methods an interface may also contain constants, default
methods, static methods, and nested types. Method bodies exist only for default
methods and static methods.
Writing an interface is similar to writing a class. But a class describes the attributes
and behaviours of an object. And an interface contains behaviours that a class
implements.
Unless the class that implements the interface is abstract, all the methods of the
interface need to be defined in the class.
5.
Write a program to demonstrate nested try block
Ans:
The try statement can be nested. That is, a try statement can be inside the block of
another try. Each time a try statement is entered, the context of that exception is
pushed on the stack. If an inner try statement does not have a catch handler for a
particular exception, the stack is
unwound and the next try statement’s catch handlers are inspected for a match. This
continues until one of the catch statements succeeds, or until all of the nested try
statements are exhausted. If no catch statement matches, then the Java run-time
system will handle the exception
// An example of nested try statements.
class NestTry {
public static void main(String args[]) {
try {
int a = args.length;
/* If no command-line args are present,
the following statement will generate
a divide-by-zero exception. */
int b = 42 / a;
System.out.println("a = " + a);
try { // nested try block
B.E/MBA/MCA/M.Tech <<Semester Number>>
10
USN
1 P E
PESIT Bangalore South Campus
Hosur road, 1km before Electronic City, Bengaluru -100
Department of Computer Science And Engineering
/* If one command-line arg is used,
then a divide-by-zero exception
will be generated by the following code. */
if(a==1) a = a/(a-a); // division by zero
/* If two command-line args are used,
then generate an out-of-bounds exception. */
if(a==2) {
int c[] = { 1 };
c[42] = 99; // generate an out-of-bounds exception
}
} catch(ArrayIndexOutOfBoundsException e) {
System.out.println("Array index out-of-bounds: " + e);
}
} catch(ArithmeticException e) {
System.out.println("Divide by 0: " + e);
}
}
}
B.E/MBA/MCA/M.Tech <<Semester Number>>