What are defender methods or virtual methods in Java?


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

Updated on: 29-Jun-2020

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