What are defender methods or virtual methods in Java?

Java 8Object Oriented ProgrammingProgramming

The default methods in an interface in Java are also known as defender methods or, virtual methods.

The defender/virtual methods are those that will have a default implementation in an interface. You can define defender/virtual methods using the default keyword as −

default void display() {
   System.out.println("This is a default method");
}

There is no need to implement these defender/virtual methods in the implementing classes you can call them directly.

If you have an interface which is implemented by some classes and if you want to add a new method int it.

Then, you need to implement this newly added method in all the exiString classes that implement this interface. Which is a lot of work.

To resolve this, you can write a default/defender/virtual method for all the newly implemented methods.

Example

Following Java Example demonstrates the usage of the default method in Java.

 Live Demo

interface sampleInterface{
   public void demo();
   default void display() {
      System.out.println("This is a default method");
   }
}
public class DefaultMethodExample implements sampleInterface{
   public void demo() {
      System.out.println("This is the implementation of the demo method");
   }
   public static void main(String args[]) {
      DefaultMethodExample obj = new DefaultMethodExample();
      obj.demo();
      obj.display();
   }
}

Output

This is the implementation of the demo method
This is a default method
raja
Published on 04-Jul-2019 16:17:30
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