How to Use Extends and Implements

Java example code, how to use extends and implements in class

package myjavaexample; 
 
public class MyJavaExample 
{ 
    private interface DoSomething 
    { 
        public void sound(); 
    } 

    private class Animal 
    { 
        public String voice="Animal"; 

        public Animal() 
        { 

        } 

        public Animal(String voice) 
        { 
            this.voice=voice; 
        } 
    } 

    private class Pet extends Animal implements DoSomething 
    { 
        public Pet() 
        { 

        } 

        public Pet(String voice) 
        { 
            super(voice); 
        } 

        public void sound() 
        { 
            System.out.println(this.voice); 
        } 
    } 

    public void experiment() 
    { 
        Pet dog=new Pet(); 
        dog.sound(); 

        Pet cat=new Pet("Miauww"); 
        cat.sound(); 

        Pet bird=new Pet("Cici"); 
        bird.sound(); 
    } 

    public static void main(String[] args) { 
        MyJavaExample main=new MyJavaExample(); 
        main.experiment(); 
    } 
}