The General Form of a Class in Java…

Example 1 : BoxDemo

import java.io.*;
class Box{
double width;
double height;
double depth;
}
class BoxDemo{
public static void main(String args[])
{
Box mybox=new Box();
double vol;
mybox.width=10;
mybox.height=20;
mybox.depth=15;
vol=mybox.width*mybox.height*mybox.depth;
System.out.println("volume is "+vol);
}
}

Example 2 : BoxDemo2

import java.io.*;
class Box{
double width;
double height;
double depth;
}
class BoxDemo2
{
public static void main(String args[])
{
Box mybox1=new Box();
Box mybox2=new Box();
double vol;
mybox1.width=10;
mybox1.height=20;
mybox1.depth=15;
mybox2.width=3;
mybox2.height=6;
mybox2.depth=9;
vol=mybox1.width*mybox1.height*mybox1.depth;
System.out.println("Volume is"+vol);
vol=mybox2.width*mybox2.height*mybox2.depth;
System.out.println("Volume is"+vol);
}
}

Assigning Object Reference Variables…

Example : ObjDemo

import java.io.*;
class ObjDemo
{
int a;
public static void main(String args[])
{
ObjDemo o1,o2;
o1=new ObjDemo();
o1.a=100;
o2=new ObjDemo();
o2.a=100;
if(o1==o2)
System.out.println("both are equal");
else
System.out.println("both are not equal");
o2=o1;
if(o1==o2)
System.out.println("both are equal");
else
System.out.println("both are not equal");
}
}