05/09/2012
1. A program to illustrate the concept of class box with constructors.
class Box
{
double width;
double height;
double depth;
Box()
{
System.out.println("Constructing Box");
width = 10;
height = 10;
depth = 10;
}
// compute and return volume
double volume()
{
return width height depth;
}
}
class BoxDemo
{
public static void main(String args[])
{
Box mybox1 = new Box();
Box mybox2 = new Box();
double vol;
vol = mybox1.volume();
System.out.println("Volume is " + vol);
vol = mybox2.volume();
System.out.println("Volume is " + vol);
}
}
OUTPUT:
Constructing Box
Constructing Box
Volume is 1000.0
Volume is 1000.0
2. A program to demonstrate method overloading.
class OverloadDemo
{
void test()
{
System.out.println("No parameters");
}
void test(int a)
{
System.out.println("a: " + a);
}
void test(int a, int b)
{
System.out.println("a and b: " + a + " " + b);
}
double test(double a)
{
System.out.println("double a: " + a);
return aa;
}
}
class Overload
{
public static void main(String args[])
{
OverloadDemo ob = new OverloadDemo();
double result;
ob.test();
ob.test(10);
ob.test(10, 20);
result = ob.test(123.25);
System.out.println("Result of ob.test(123.25):" +result);
}
}
OUTPUT:
No parameters
a: 10
a and b: 10 20
double a: 123.25
Result of ob.test(123.25): 15190.5625
3. A Java program to demonstrate inheritance.
class A
{
int i, j;
void showij()
{
System.out.println("i and j: " + i + " " + j);
}
}
class B extends A
{
int k;
void showk()
{
System.out.println("k: " + k);
}
void sum()
{
System.out.println("i+j+k: " + (i+j+k));
}
}
class SimpleInheritance
{
public static void main(String args[])
{
A superOb = new A();
B subOb = new B();
superOb.i = 10;
superOb.j = 20;
System.out.println("Contents of superOb: ");
superOb.showij();
System.out.println();
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();
}
}
OUTPUT:
Contents of superOb:
i and j: 10 20
Contents of subOb:
i and j: 7 8
k: 9
Sum of i, j and k in subOb:
i+j+k: 24.
4. A Java program to demonstrate dynamic polymorphism.
class Figure
{
double dim1;
double dim2;
Figure(double a, double b)
{
dim1 = a;
dim2 = b;
}
double area() {
System.out.println("Area for Figure is undefined.");
return 0;
}
}
class Rectangle extends Figure
{
Rectangle(double a, double b)
{
super(a, b);
}
double area()
{
System.out.println("Inside Area for Rectangle.");
return dim1 dim2;
}
}
class Triangle extends Figure
{
Triangle(double a, double b)
{
super(a, b);
}
double area()
{
System.out.println("Inside Area for Triangle.");
return dim1 dim2 / 2;
}
}
class FindAreas
{
public static void main(String args[])
{
Figure f = new Figure(10, 10);
Rectangle r = new Rectangle(9, 5);
Triangle t = new Triangle(10, 8);
Figure figref;
figref = r;
System.out.println("Area is " + figref.area());
figref = t;
System.out.println("Area is " + figref.area());
figref = f;
System.out.println("Area is " + figref.area());
}
}
OUTPUT:
Inside Area for Rectangle.
Area is 45
Inside Area for Triangle.
Area is 40
Area for Figure is undefined.
Area is 0
5. A Java program to implement the following hierarchy and find area.
abstract class Figure
{
double dim1;
double dim2;
Figure(double a, double b)
{
dim1 = a;
dim2 = b;
}
abstract double area();
}
class Rectangle extends Figure
{
Rectangle(double a, double b)
{
super(a, b);
}
double area()
{
System.out.println("Inside Area for Rectangle.");
return dim1 dim2;
}
}
class Triangle extends Figure
{
Triangle(double a, double b)
{
super(a, b);
}
double area()
{
System.out.println("Inside Area for Triangle.");
return dim1 dim2 / 2;
}
}
class AbstractAreas
{
public static void main(String args[])
{
Rectangle r = new Rectangle(9, 5);
Triangle t = new Triangle(10, 8);
Figure figref; figref = r;
System.out.println("Area is " + figref.area());
figref = t;
System.out.println("Area is " + figref.area());
}
}
OUTPUT:
Inside Area for Rectangle.
Area is 45.0
Inside Area for Triangle.
Area is 40.0
6. A Java Program to implement an Animal Abstract class.
abstract class Animal
{
abstract void name();
abstract void colour();
void legs()
{
System.out.println("leg() called");
}
}
class Sample extends Animal
{
void name()
{
System.out.println("name() called");
}
void colour()
{
System.out.println("colour() called");
}
}
class Test
{
public static void main(String []args)
{
Sample s=new Sample();
s.name();
s.colour();
s.legs();
}
}
OUTPUT:
name() called
colour() called
leg() called
7. A Java program on multithreading by using Runnable interface.
class NewThread implements Runnable
{
String name;
Thread t;
NewThread(String threadname)
{
name = threadname;
t = new Thread(this, name);
System.out.println("New thread: " + t);
t.start();
}
public void run()
{
try {
for(int i = 5; i > 0; i--)
{
System.out.println(name + ": " + i);
Thread.sleep(1000);
}
}
catch (InterruptedException e)
{
System.out.println(name + "Interrupted");
}
System.out.println(name + " exiting.");
}
}
class MultiThreadDemo
{
public static void main(String args[])
{
new NewThread("One");
new NewThread("Two");
new NewThread("Three");
try
{
Thread.sleep(10000);
}
catch(InterruptedException e)
{
System.out.println("Main thread Interrupted");
}
System.out.println("Main thread exiting.");
}
}
OUTPUT:
New thread: Thread[One,5,main]
New thread: Thread[Two,5,main]
New thread: Thread[Three,5,main]
One: 5
Two: 5
Three: 5
One: 4
Two: 4
Three: 4
One: 3
Three: 3
Two: 3
One: 2
Three: 2
Two: 2
One: 1
Three: 1
Two: 1
One exiting.
Two exiting.
Three exiting.
Main thread exiting.
8. A Java program on multithreading by using the thread class, and also use the yield(), stop(), sleep() methods.
import java.util.;
public YieldDemo extends Thread
{
public void run()
{
for(int i=0;i
