implementing the runnable interface in java in hindi | implementation in java interface

Implementing Interfaces in Java

When a class implements an interface, you can think of the class as signing a contract, agreeing to perform the specific behaviors of the interface. If a class does not perform all the behaviors of the interface, the class must declare itself as abstract.

A class uses the implements keyword to implement an interface. The implements keyword appears in the class declaration following the extends portion of the declaration.

interface in java

Example

/* File name : MammalInt.java */

public class MammalInt implements Animal {

   public void eat() {

      System.out.println("Mammal eats");

   }

   public void travel() {

      System.out.println("Mammal travels");

   }

   public int noOfLegs() {

      return 0;

   }

   public static void main(String args[]) {

      MammalInt m = new MammalInt();

      m.eat();

      m.travel();

   }

}

Output:

Mammal eats

Mammal travels

When overriding methods defined in interfaces, there are several rules to be followed −

·        Checked exceptions should not be declared on implementation methods other than the ones declared by the interface method or subclasses of those declared by the interface method.

·        The signature of the interface method and the same return type or subtype should be maintained when overriding the methods.

·        An implementation class itself can be abstract and if so, interface methods need not be implemented.

When implementation interfaces, there are several rules −

·        A class can implement more than one interface at a time.

·        A class can extend only one class, but implement many interfaces.

·        An interface can extend another interface, in a similar way as a class can extend another class.

implementation in java