static boolean flag = true;

static Object lock = new Object();

public static void main(String[] args) throws Exception {

Thread waitThread = new Thread(new Wait(), "WaitThread");

waitThread.start();

TimeUnit.SECONDS.sleep(1);

Thread notifyThread = new Thread(new Notify(), "NotifyThread");

notifyThread.start();

}

static class Wait implements Runnable {

public void run() {

// 加锁，拥有lock的Monitor

synchronized (lock) {

// 当条件不满足时，继续wait，同时释放了lock的锁

while (flag) {

try {

System.out.println(Thread.currentThread() + " flag is true. wait @ "

+ new SimpleDateFormat("HH:mm:ss").format(new Date()));

lock.wait();

} catch (InterruptedException e) {

}

}

// 条件满足时，完成工作

System.out.println(Thread.currentThread() + " flag is false. running @ "

+ new SimpleDateFormat("HH:mm:ss").format(new Date()));

}

}

}

static class Notify implements Runnable {

public void run() {

// 加锁，拥有lock的Monitor

synchronized (lock) {

// 获取lock的锁，然后进行通知，通知时不会释放lock的锁，

// 直到当前线程释放了lock后，WaitThread才能从wait方法中返回

System.out.println(Thread.currentThread() + " hold lock. notify @ " + new SimpleDateFormat("HH:mm:ss").format(new Date()));

lock.notifyAll();

flag = false;

SleepUtils.second(5);

}

// 再次加锁

synchronized (lock) {

System.out.println(Thread.currentThread() + " hold lock again. sleep @ "

+ new SimpleDateFormat("HH:mm:ss").format(new Date()));

SleepUtils.second(5);

}

}

}

}