详解Java中的sleep()和wait()的区别

/**
 * 
 */
package com.b510.test;

/**
 * java中的sleep()和wait()的区别
 * @author Hongten Java学习交流QQ群：589809992 我们一起学Java！
 * @date 2013-12-10
 */
public class TestD {

  public static void main(String[] args) {
    new Thread(new Thread1()).start();
    try {
      Thread.sleep(5000);
    } catch (Exception e) {
      e.printStackTrace();
    }
    new Thread(new Thread2()).start();
  }

  private static class Thread1 implements Runnable{
    @Override
    public void run(){
      synchronized (TestD.class) {
      System.out.println("enter thread1...");  
      System.out.println("thread1 is waiting...");
      try {
        //调用wait()方法，线程会放弃对象锁，进入等待此对象的等待锁定池
        TestD.class.wait();
      } catch (Exception e) {
        e.printStackTrace();
      }
      System.out.println("thread1 is going on ....");
      System.out.println("thread1 is over!!!");
      }
    }
  }

  private static class Thread2 implements Runnable{
    @Override
    public void run(){
      synchronized (TestD.class) {
        System.out.println("enter thread2....");
        System.out.println("thread2 is sleep....");
        //只有针对此对象调用notify()方法后本线程才进入对象锁定池准备获取对象锁进入运行状态。
        TestD.class.notify();
        //==================
        //区别
        //如果我们把代码：TestD.class.notify();给注释掉，即TestD.class调用了wait()方法，但是没有调用notify()
        //方法，则线程永远处于挂起状态。
        try {
          //sleep()方法导致了程序暂停执行指定的时间，让出cpu该其他线程，
          //但是他的监控状态依然保持者，当指定的时间到了又会自动恢复运行状态。
          //在调用sleep()方法的过程中，线程不会释放对象锁。
          Thread.sleep(5000);
        } catch (Exception e) {
          e.printStackTrace();
        }
        System.out.println("thread2 is going on....");
        System.out.println("thread2 is over!!!");
      }
    }
  }
}

enter thread1...
thread1 is waiting...
enter thread2....
thread2 is sleep....
thread2 is going on....
thread2 is over!!!
thread1 is going on ....
thread1 is over!!!

1 TestD.class.notify();

enter thread1...
thread1 is waiting...
enter thread2....
thread2 is sleep....
thread2 is going on....
thread2 is over!!!