package concurrency;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

class Athlete implements Runnable {
  private final int id;
  private Game game;

  public Athlete(int id, Game game) {
   this.id = id;
   this.game = game;
  }

  public boolean equals(Object o) {
   if (!(o instanceof Athlete))
    return false;
   Athlete athlete = (Athlete) o;
   return id == athlete.id;
  }

  public String toString() {
   return "Athlete<" + id + ">";
  }

  public int hashCode() {
   return new Integer(id).hashCode();
  }

  public void run() {
   try {
    game.prepare(this);
   } catch (InterruptedException e) {
    System.out.println(this + " quit the game");
   }
  }
 }

public class Game implements Runnable {
  private Set<Athlete> players = new HashSet<Athlete>();
  private boolean start = false;

  public void addPlayer(Athlete one) {
   players.add(one);
  }

  public void removePlayer(Athlete one) {
   players.remove(one);
  }

  public Collection<Athlete> getPlayers() {
   return Collections.unmodifiableSet(players);
  }

  public void prepare(Athlete athlete) throws InterruptedException {
   System.out.println(athlete + " ready!");
   synchronized (this) {
    while (!start)
    wait();
    if (start)
     System.out.println(athlete + " go!");
   }
  }

  public synchronized void go() {
   notifyAll();
  }
  
  public void ready() {
   Iterator<Athlete> iter = getPlayers().iterator();
   while (iter.hasNext())
    new Thread(iter.next()).start();
  }

  public void run() {
   start = false;
   System.out.println("Ready......");
   System.out.println("Ready......");
   System.out.println("Ready......");
   ready();
   start = true;
   System.out.println("Go!");
   go();
  }

  public static void main(String[] args) {
   Game game = new Game();
   for (int i = 0; i < 10; i++)
    game.addPlayer(new Athlete(i, game));
   new Thread(game).start();
  }
}

Ready......
Ready......
Ready......
Athlete<0> ready!
Athlete<1> ready!
Athlete<2> ready!
Athlete<3> ready!
Athlete<4> ready!
Athlete<5> ready!
Athlete<6> ready!
Athlete<7> ready!
Athlete<8> ready!
Athlete<9> ready!
Go!
Athlete<9> go!
Athlete<8> go!
Athlete<7> go!
Athlete<6> go!
Athlete<5> go!
Athlete<4> go!
Athlete<3> go!
Athlete<2> go!
Athlete<1> go!
Athlete<0> go!

import java.util.concurrent.TimeUnit;

class MyObject implements Runnable {
  private Monitor monitor;

  public MyObject(Monitor monitor) {
   this.monitor = monitor;
  }

  public void run() {
   try {
    TimeUnit.SECONDS.sleep(3);
    System.out.println("i'm going.");
    monitor.gotMessage();
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
}

class Monitor implements Runnable {
  private volatile boolean go = false;

  public void gotMessage() throws InterruptedException {
   go = true;
  }

  public void watching() {
   while (go == false)
    ;
   System.out.println("He has gone.");
  }

  public void run() {
   watching();
  }
}

public class BusyWaiting {
  public static void main(String[] args) {
   Monitor monitor = new Monitor();
   MyObject o = new MyObject(monitor);
   new Thread(o).start();
   new Thread(monitor).start();
  }
}

i'm going.
He has gone.

package concurrency.wait;

import java.util.concurrent.TimeUnit;

class MyObject implements Runnable {
  private Monitor monitor;

  public MyObject(Monitor monitor) {
   this.monitor = monitor;
  }

package java.util.concurrent;
import java.util.*;
public interface Delayed extends Comparable<Delayed> {
  long getDelay(TimeUnit unit);
}

package com.zj.timedtask;

import static java.util.concurrent.TimeUnit.SECONDS;
import static java.util.concurrent.TimeUnit.NANOSECONDS;

import java.util.Collection;
import java.util.Collections;
import java.util.Random;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class DelayedTasker implements Runnable {
  DelayQueue<DelayedTask> queue = new DelayQueue<DelayedTask>();

  public void addTask(DelayedTask e) {
    queue.put(e);
  }

  public void removeTask() {
    queue.poll();
  }

  public Collection<DelayedTask> getAllTasks() {
    return Collections.unmodifiableCollection(queue);
  }

  public int getTaskQuantity() {
    return queue.size();
  }

  public void run() {
    while (!queue.isEmpty())
      try {
       queue.take().run();
      } catch (InterruptedException e) {
       System.out.println("Interrupted");
      }
    System.out.println("Finished DelayedTask");
  }

  public static class DelayedTask implements Delayed, Runnable {
    private static int counter = 0;
    private final int id = counter++;
    private final int delta;
    private final long trigger;

    public DelayedTask(int delayInSeconds) {
      delta = delayInSeconds;
      trigger = System.nanoTime() + NANOSECONDS.convert(delta, SECONDS);
    }

    public long getDelay(TimeUnit unit) {
      return unit.convert(trigger - System.nanoTime(), NANOSECONDS);
    }

    public int compareTo(Delayed arg) {
      DelayedTask that = (DelayedTask) arg;
      if (trigger < that.trigger)
       return -1;
      if (trigger > that.trigger)
       return 1;
      return 0;
    }

    public void run() {
      //run all that you want to do
      System.out.println(this);
    }

    public String toString() {
      return "[" + delta + "s]" + "Task" + id;
    }
  }

  public static void main(String[] args) {
    Random rand = new Random();
    ExecutorService exec = Executors.newCachedThreadPool();
    DelayedTasker tasker = new DelayedTasker();
    for (int i = 0; i < 10; i++)
      tasker.addTask(new DelayedTask(rand.nextInt(5)));
    exec.execute(tasker);
    exec.shutdown();
  }
}

[0s]Task 1
[0s]Task 2
[0s]Task 3
[1s]Task 6
[2s]Task 5
[3s]Task 8
[4s]Task 0
[4s]Task 4
[4s]Task 7
[4s]Task 9
Finished DelayedTask

package com.zj.timedtask;

import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class ScheduleTasker {
  private int corePoolSize = 10;
  ScheduledThreadPoolExecutor scheduler;

  public ScheduleTasker() {
    scheduler = new ScheduledThreadPoolExecutor(corePoolSize);
  }

  public ScheduleTasker(int quantity) {
    corePoolSize = quantity;
    scheduler = new ScheduledThreadPoolExecutor(corePoolSize);
  }

  public void schedule(Runnable event, long delay) {
    scheduler.schedule(event, delay, TimeUnit.SECONDS);
  }

  public void shutdown() {
    scheduler.shutdown();
  }

  public static void main(String[] args) {
    ScheduleTasker tasker = new ScheduleTasker();
    tasker.schedule(new Runnable() {
      public void run() {
       System.out.println("[1s]Task 1");
      }
    }, 1);
    tasker.schedule(new Runnable() {
      public void run() {
       System.out.println("[2s]Task 2");
      }
    }, 2);
    tasker.schedule(new Runnable() {
      public void run() {
       System.out.println("[4s]Task 3");
      }
    }, 4);
    tasker.schedule(new Runnable() {
      public void run() {
       System.out.println("[10s]Task 4");
      }
    }, 10);

    tasker.shutdown();
  }
}

[1s]Task 1
[2s]Task 2
[4s]Task 3
[10s]Task 4
  public void run() {
   try {
    TimeUnit.SECONDS.sleep(3);
    System.out.println("i'm going.");
    monitor.gotMessage();
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
}

class Monitor implements Runnable {
  private volatile boolean go = false;

  public synchronized void gotMessage() throws InterruptedException {
   go = true;
   notify();
  }

  public synchronized void watching() throws InterruptedException {
   while (go == false)
    wait();
   System.out.println("He has gone.");
  }

  public void run() {
   try {
    watching();
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
}

public class Wait {
  public static void main(String[] args) {
   Monitor monitor = new Monitor();
   MyObject o = new MyObject(monitor);
   new Thread(o).start();
   new Thread(monitor).start();
  }
}

i'm going.
He has gone.