What is interface in Java with realtime Example?

Java interface realtime examples

Summary: By the end of this tutorial "Java interface realtime examples", you know what is interface with realtime examples.

Java interface realtime examples

1. Interface differs from abstract class in that interface contains only abstract methods. All methods should be public and abstract; if just omitted by the Programmer by style, Java assumes by default.
2. Apart abstract methods, the interface can contain variables also. The variables should be declared as public, static and final and if not declared, they assumed by default.
3. With interfaces, we cannot create objects as methods do not have body an thereby cannot give any output.
4. The subclass that implements the interface should override all the abstract methods; omitting one, the compiler does not compile the program.
5. Advantages with interfaces
   1. The benefits interface offers is it allows multiple inheritance which is not possible with concrete classes and abstract classes.
   2. With interfaces, implements keyword is to be used instead of general extends keyword. Implements informs the compiler that what ever classes are there after implements, they are interfaces.
   3. An interface gives template structure of methods from which new classes can be developed easily.
   4. The same abstract methods of the interface can be overridden with different functionalities by different subclasses.

Elaborate explanation with example and screenshots in questions and answers form easy to understand is available at Why interface required in Java – a full discussion with Example?.