Java_014：WAITING线程例子 （摘录+整理）

1.  WaitThread.java

public class WaitThread implements Runnable{

public void run() {

        synchronized(this) {

                try {

                                this.wait();

                      } catch (InterruptedException e) {

                                // TODO Auto-generated catch block

                                e.printStackTrace();

                      }

        }

   }

   public static void main(String[] args) {

        WaitThread t1 = new WaitThread();

        Thread ta = new Thread(t1, "A");

        Thread tb = new Thread(t1, "B");

        ta.start();

        tb.start();

   }

}

2. 线程A和线程B的thread dump
（1）线程A的状态是in Object.wait()：WAITING (on object monitor)。
（2）线程B的状态也是in Object.wait()：WAITING (on object monitor)。

"B" prio=5 tid=0x00007fc16d83d000 nid=0x5903 in Object.wait() [0x00000001215cb000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007aab2bc80> (a WaitThread)
at java.lang.Object.wait(Object.java:503)
at WaitThread.run(WaitThread.java:5)
- locked <0x00000007aab2bc80> (a WaitThread)
at java.lang.Thread.run(Thread.java:744)

"A" prio=5 tid=0x00007fc16d83c000 nid=0x5703 in Object.wait() [0x00000001214c8000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007aab2bc80> (a WaitThread)
at java.lang.Object.wait(Object.java:503)
at WaitThread.run(WaitThread.java:5)
- locked <0x00000007aab2bc80> (a WaitThread)
at java.lang.Thread.run(Thread.java:744)

原因解释：
线程A获取Monitor后：locked <0x00000007aab2bc80>，又调用wait()，释放了锁：waiting on <0x00000007aab2bc80>。
因为线程A释放了锁<0x00000007aab2bc80>，线程B得以获取该锁，然后线程B也调用wait()，释放了该锁。
现在，线程A和线程B都在等待其它线程调用锁对象的notify()或notifyall()方法，将它们再次“唤醒”。