Question

我还在学习oracle网站的java教程后的Threads。

关于wait（）和notifyAll（），我写了一些代码。我的预期输出是在run（）中打印10次消息并打印＆＃34;由StopFun Thread＆＃34;当“快乐”时，guardedJoy(GuardedBlock guardedBlock)方法中的消息在run方法中设置为false。

这是我的代码。

public class GuardedBlock {

private boolean joy = true;

public synchronized void guardedJoy(GuardedBlock guardedBlock) {

    System.out.println(Thread.currentThread().getName() + " Guard Joy method started");
    while (guardedBlock.joy) {
        try {
            System.out.println(Thread.currentThread().getName() + " Going to waiting state");
            guardedBlock.wait();
        } catch (InterruptedException ex) {
        }
    }
    System.out.println("Fun stopped by StopFun Thread");
}

private static class StopFun implements Runnable {

    private GuardedBlock guardedBlock;

    public StopFun(GuardedBlock guardedBlock) {
        this.guardedBlock = guardedBlock;
    }

    @Override
    public void run() {

        for (int x = 0; x < 100; x++) {
            try {
                Thread.sleep(500);
                System.out.println("Allowing fun since its only " + x + " times - " + Thread.currentThread().getName());

                if (x == 10) {
                    guardedBlock.joy = false;
                    guardedBlock.notifyAll();
                    break;
                }
            } catch (InterruptedException ex) {
            }
        }
    }
}

public static void main(String[] args) {

    GuardedBlock guardedBlock = new GuardedBlock();

    StopFun sf = new StopFun(guardedBlock);
    Thread stopFun = new Thread(sf);
    stopFun.start();

    guardedBlock.guardedJoy(guardedBlock);
    }
}

run方法中的代码运行正常，但之后会抛出这样的异常。

Exception in thread "Thread-0" java.lang.IllegalMonitorStateException
    at java.lang.Object.notifyAll(Native Method)
    at Synchronization.GuardedBlock$StopFun.run(GuardedBlock.java:38)
    at java.lang.Thread.run(Thread.java:748)

我在网站上经历了几个问题和答案，例如this和this，但无法弄清楚我到底做错了什么。帮助很有价值。

感谢。

Answer 1

必须在wait()块中调用

notify()和notifyAll() / synchronized。

synchronized (guardedBlock) {
    guardedBlock.notifyAll();
}

等等。

关于notifyAll（）方法的java.lang.IllegalMonitorStateException

1 个答案: