Chapter 9.3.1 : Declaring Interfaces

The interface keyword is used to declare an interface. Here is a simple example to declare an interface:

Example:

Let us look at an example that depicts encapsulation:

/* File name : NameOfInterface.java */

import java.lang.*;

//Any number of import statements

public interface NameOfInterface

{

   //Any number of final, static fields

   //Any number of abstract method declarations\

}

Interfaces have the following properties:

·         An interface is implicitly abstract. You do not need to use the abstract keyword when declaring an interface.

·         Each method in an interface is also implicitly abstract, so the abstract keyword is not needed.

·         Methods in an interface are implicitly public.

Example:

/* File name : Animal.java */

interface Animal {

   public void eat();

   public void travel();

}