sleep()和wait()的区别？

sleep是线程类（Thread）的方法，导致此线程暂停执行指定时间（Thread.sleep(1000)），把执行机会给其它线程，但监控状态依然保持，到时候自动恢复；调用sleep不会释放对象锁。
wait是Object类的方法，对此对象调用wait方法导致本线程放弃对象锁，进入等待此对象的等待锁定池，只有针对此对象发出notify方法(或notifyAll)后本线程才进入对象锁定池准备获得对象锁进入运行状态。

public class Test {
  public static void main(String[] args) {
    new TestThread().start();
    new TestThread().start();
    new TestThread().start();
  }
}

class TestThread extends Thread {
  private static Object lock = new Object();

  public void run() {
    while (true) {
      try {
        Thread.sleep(1);
      } catch (Exception ex) {}
      synchronized (lock) {
        System.out.println(this.getId());
        try {
          notifyAll();
          this.wait();
          try {
            Thread.sleep(1);
          } catch (Exception ex) {}
        } catch (Exception ex) {}
        System.out.println(this.getId());
      }
    }
  }
}

public class Test {
  public static void main(String[] args) {
    new TestThread().start();
    new TestThread().start();
    new TestThread().start();
  }
}

class TestThread extends Thread {
  private static Object lock = new Object();

  public void run() {
    while (true) {
      try {
        Thread.sleep(1);
      } catch (Exception ex) {}
      synchronized (lock) {
        System.out.println(this.getId());
        try {
          notifyAll();
          this.wait();
          try {
            Thread.sleep(1);
          } catch (Exception ex) {}
        } catch (Exception ex) {}
        System.out.println(this.getId());
      }
    }
  }
}

输出
9
9
10
10
8
8
10
10
8
8
9
9
8