Class & object in Java

A class is often defined as the blueprint or template for an object. We can create multiple objects from a class.

An object is an identifiable entity with some characteristics, state and behaviour.

Memory is allocated when we create the objects of a class type. A class contains properties and methods to define the state and behaviour of its object. It defines the data and the methods that act upon that data.

Example :
   A dog has states - color, name, breed as well as behaviors – wagging the tail, barking, eating. An object is an instance of a class.

Syntax Of Class :
   class class_name
        Variables ;
        Methods ;

Syntax Of Object :
   Class_Name ReferenceVariable ( or ) Object = new Class_Name ( ) ;

Source Code

//Class & Object in Java
class Rectangle
    int length, width;
    void getDetails(int x, int y) {
        length = x;
        width = y;
    int area() {
        int a = length * width;
        return a;
public class class_object {
    public static void main(String args[]) {
        Rectangle o1 =new Rectangle();
        System.out.println("Area of Rectangle : "+o1.area());
        Rectangle o2=new Rectangle();
        System.out.println("Area of Rectangle : "+o2.area());


Area of Rectangle : 200
Area of Rectangle : 600
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Basic Programs