Class and Objects in Java

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Class and Objects

Class : A class can be defined as a blueprint or a set of instruction to build a  specific type of object. Class show how to declare fields, methods, and constructors.

we declare a class by specifying the class keyword followed by a non-reserved identifier that names it. A pair of matching open and close brace characters ({ and }) following it.

class className      





E.g. : class Student


Int rollno;

String name;

void setRollno( );



Objects : Objects have states and behaviors. 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.

Other definitions of object include :

  • Object is a real world entity.
  • Object is a run time entity.
  • Object is an entity which has state and behavior.
  • Object is an instance of a class.