等待与通知

public final void wait() throws InterruptedException;
public final native void notify();
public final native void notifyAll();

obj.wait()唤醒条件

• 其它线程调用了obj.notify();
• 其它线程调用了obj.notifyAll();
• wait(毫秒数)达到指定的时间后自然被激活

说明：在SUN Jdk中，object.wait()还有可能被假唤醒，因此在object.wait被唤醒后应再次确认需要等待的状态是否变更了，如果未变更则继续进入wait状态，这种做法通称为double check

中断响应

wait方法支持响应中断

public final void wait() throws InterruptedException {
        wait(0);
}

public final native void wait(long timeout) throws InterruptedException;

示例：

public class Appliction {
    private static Object lock = new Object();
    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(() -> {
            synchronized (lock){
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.err.println(Thread.currentThread().getName() + " canceled===>");
        });
        thread.start();
        TimeUnit.SECONDS.sleep(3);
        thread.interrupt();
        System.err.println(Thread.currentThread().getName() + " finished===>");
    }
}

知识点

• wait()方法在执行后会释放监视锁
• Object.wait()与Thread.sleep()方法的主要区别是wait()方法会释放目标对象的监视锁，而sleep()方法不会释放任何资源