//Listing 6-5. Using a Phaser to Control a One-Shot Action Serving a Variable Number

//of Parties

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.Executors;

import java.util.concurrent.Phaser;

public class A {

    public static void main(String[] args)

{

    List<Runnable> tasks = new ArrayList<>();

    tasks.add(() -> System.out.printf("%s running at %d%n",

    Thread.currentThread().getName(),

    System.currentTimeMillis()));

    tasks.add(() -> System.out.printf("%s running at %d%n",

    Thread.currentThread().getName(),

    System.currentTimeMillis()));

    runTasks(tasks);

}

    static void runTasks(List<Runnable> tasks)

    {

        final Phaser phaser = new Phaser(); // "1" (register self)

        // create and start threads

        for (final Runnable task: tasks)

        {

        phaser.register();

        Runnable r = () ->

        {

            try

            {

                Thread.sleep( + (int) (Math.random() * ));

            }

            catch (InterruptedException ie)

            {

                System.out.println("interrupted thread");

            }

            phaser.arriveAndAwaitAdvance(); // await the ...

            // creation of ...

            // all tasks

            task.run();

        };

        Executors.newSingleThreadExecutor().execute(r);

        }

        // allow threads to start and deregister self

        phaser.arriveAndDeregister();

}

}