What are the differences between Java classes and Java objects?

Java 8Object Oriented ProgrammingProgramming

A class can be defined as a template/blueprint that describes the behaviour/state that the object of its type support.

Example

public class Dog {
   String breed;
   int age;
   
   String color;
   void barking() {
   }
   void hungry() {
   }
   void sleeping() {
   }
}

Objects have states and behaviours. Example: A dog has states - colour, name, breed as well as behaviours – wagging the tail, barking, eating. An object is an instance of a class.

An object is created from a class. In Java, the new keyword is used to create new objects.

There are three steps when creating an object from a class −

  • Declaration − A variable declaration with a variable name with an object type.

  • Instantiation − The 'new' keyword is used to create the object.

  • Initialization − The 'new' keyword is followed by a call to a constructor. This call initializes the new object.

Following is an example of creating an object −

Example

Live Demo

public class Puppy {
   public Puppy(String name) {
      // This constructor has one parameter, name.
      System.out.println("Passed Name is :" + name );
   }
   public static void main(String []args) {
      // Following statement would create an object myPuppy
      Puppy myPuppy = new Puppy( "tommy" );
   }
}

Output

Passed Name is :tommy
raja
Published on 09-Feb-2018 11:27:35
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