public class CountDown {

    // A Java code that creates 5 parallel tasks

    // performing countdown from 5 to 0

    public static void main(String[] args) {

        CountDown application = new CountDown();

        application.start();    

    }

    // Method for spawning 5 parallel threads of execution

    public void start() {

        for(int i=1; i<=5; i++)

            new Thread(new CountDownHandler(5, i)).start();

    }

    // Utility class for handling count down per thread

    // that implements the Runnable interface

    private class CountDownHandler implements Runnable {

        private int id;

        private int counter;

        public CountDownHandler(int counter, int id) {

            this.counter = counter;

            this.id = id;

        }

        public String status() {

            return "id#" + id + " " +

            ((counter >= 0) ? counter : "LiftOff!");

        }

        public void run() {

            while(counter >= -1) {

                System.out.println(status());

                counter--;

                try {

                    Thread.sleep(1000);

                } catch(Exception e) {

​

                }

            }

        }

    }

}

// Java Program to implement Runnable interface

// Importing FileNotFound class from

// input output classes bundle

import java.io.FileNotFoundException;

import java.util.concurrent.*;

// Class

// Implementing the Runnable interface

class RunnableImpl implements Runnable {

  public void run()

  {

    System.out.println("Hello World from a different thread than Main");

  }

}

public class RunnableExample{

    static ExecutorService executor = Executors.newFixedThreadPool(2);

  public static void main(String[] args){

          // Creating and running runnable task using Thread class

          RunnableImpl task = new RunnableImpl();

        Thread thread = new Thread(task);

          thread.start();

          // Creating and running runnable task using Executor Service.

          executor.submit(task);

    }

}

@FunctionalInterface

public interface Runnable {

    public abstract void run();

}