### 等待与通知 wait方法的语义有两个，一个是释放当前的对象锁、另一个是使得当前线程进入阻塞队列， 而这些操作都和监视器是相关的，所以wait必须要获得一个监视器锁 ``` 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