Wait（） notify（）同步

Wait（）/ notify（）同步

对象监视器锁需要执行相同锁的单个引用。

在你的榜样，你是

waiting

对的一个实例

Thread

，但使用

notify

从

Runnable

。相反，您应该使用单个通用锁定对象…例如

public class Tester {    public static final Object LOCK = new Object();    public static void main(String[] args) {        MyRunnable r = new MyRunnable();        Thread t = new Thread(r);        t.start();        synchronized (LOCK) { try {     System.out.println("wating for t to complete");     LOCK.wait();     System.out.println("wait over"); } catch (InterruptedException e) {     e.printStackTrace(); }        }    }    public static class MyRunnable implements Runnable {        public void run() { System.out.println("entering run method"); synchronized (LOCK) {     System.out.println("entering syncronised block");     LOCK.notify();     try {         Thread.currentThread().sleep(1000);     } catch (InterruptedException e) {         e.printStackTrace();     }     System.out.println("leaving syncronized block"); } System.out.println("leaving run method");        }    }}

输出…

wating for t to completeentering run methodentering syncronised blockleaving syncronized blockwait overleaving run method

wait over

并

leaving run method

可能根据线程调度更改位置。

您可以尝试将睡眠排除在

synchronized

障碍之外。这将释放监视器锁定，从而允许该

wait

部分继续运行（因为在锁定释放之前它无法启动）

    public static class MyRunnable implements Runnable {        public void run() { System.out.println("entering run method"); synchronized (LOCK) {     System.out.println("entering syncronised block");     LOCK.notify();     System.out.println("leaving syncronized block"); } try {     Thread.currentThread().sleep(1000); } catch (InterruptedException e) {     e.printStackTrace(); } System.out.println("leaving run method");        }    }