/*

 下面的程序会出现下面的情况，当Thread-0， Thread-1， Thread-2都被wait的时候，可能会同时苏醒

     Thread-0 put

     Thread-1 put

     Thread-2 put

     Thread-3 get//在此处，Thread-3拿到锁之后，将所有的等待的线程唤醒，才有了下面的输出

     Thread-2 put

     Thread-1 put

     Thread-0 put

 */

    虽然多个线程会同时苏醒，但是只有一个能获得cpu的执行权！

    总之，同步中执行的只能是一个，但是存活的不一定就是一个！

 class DuckD{

     public void put(){

         synchronized(DuckD.class){

               System.out.println(Thread.currentThread().getName()+" put");

               try{

                  DuckD.class.wait();//Thread-0， Thread-1， Thread-2可能会同时在这里苏醒！

               }catch(InterruptedException e){

               }

               //........

         }

     }

     public void get(){

         synchronized(DuckD.class){

                 DuckD.class.notifyAll();

               System.out.println(Thread.currentThread().getName()+" get");

               try{

                  DuckD.class.wait();

               }catch(InterruptedException e){

               }

         }

     }

 }

 class ProduceD implements Runnable{

     DuckD dk;

     ProduceD(DuckD dk){

        this.dk=dk;

     }

     public void run(){

        while(true)

          dk.put();

     }

 }

 class ConsumeD implements Runnable{

     DuckD dk;

     ConsumeD(DuckD dk){

        this.dk=dk;

     }

     public void run(){

         while(true)

           dk.get();

     }

 }

 class Test{

    public static void main(String[] args){

        DuckD dk=new DuckD();

        Thread t1=new Thread(new ProduceD(dk));

        Thread t2=new Thread(new ProduceD(dk));

        Thread t3=new Thread(new ProduceD(dk));

        Thread t4=new Thread(new ConsumeD(dk));

        t1.start();

        t2.start();

        t3.start();

        t4.start();

    }

 }