HackerRank Java Inheritance I problem solution

In this HackerRank Java Inheritance problem in java programming language You must add a sing method to the Bird class, then modify the main method accordingly so that the code prints the following lines:

1. I am walking
2. I am flying
3. I am singing

HackerRank Java Inheritance I problem solution.

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

class Animal{
    void walk(){
        System.out.println("I am walking");
    }
}

class Bird extends Animal implements asd{
    void fly(){
        System.out.println("I am flying");
    }
    public void sing() {
        System.out.println("I am singing");
    }
}
interface asd{
    void sing();
}

public class Solution{

   public static void main(String args[]){

      Bird bird = new Bird();
      bird.walk();
      bird.fly();
      bird.sing();
    
   }
}

Second solution

class Animal{
   void walk()
   {
      System.out.println("I am walking");
   }
}

class Bird extends Animal
{
   void fly()
   {
      System.out.println("I am flying");
   }
    
    void sing(){
        System.out.println("I am singing");
    }
}
public class Solution
{

   public static void main(String args[])
   {

     Bird bird = new Bird();
     bird.walk();
     bird.fly();
     bird.sing();
   
   }
}

The solution in java8 programming.

class Animal{
   void walk()
   {
      System.out.println("I am walking");
   }
}

class Bird extends Animal
{
   void fly()
   {
      System.out.println("I am flying");
   }
   void sing()
   {
       System.out.println("I am singing");
   }
}
public class Solution
{

   public static void main(String args[])
   {

     Bird bird = new Bird();
     bird.walk();
     bird.fly();
     bird.sing();
   
   }
}