Java Classes and Objects


A class forms the basis for object-oriented programming. It defines the shape and nature of the object.

Any concept that we want to implement in oop’s must be encapsulated within a class. A class is a template for an object and an object is an instance for a class.

In another words class is a user defined data type.


An object is a run time entity which has state and behavior. Example: A dog has states – name, breed ,color, etc. and behaviors – barking, eating etc.

It is a basic unit of Object Oriented Programming and represents the real-life entities. In a java program, we can create many objects and it is an instance of a class.

How to create object

Syntex for object:   

new operator dynamically allocates  memory for an object

Write a program to demonstrate class and variables.


In above program we can create an object in two lines as.                                                    

 First line declares the obj1 as a reference to an object. After this line obj1 contains a null value. Any attempt to  use obj1 at this point will result in compile time error.

Next line allocates a RectangleArea  object.