生产者消费者的Java实现抛出java.lang.IllegalMonitorStateException

Question

import java.util.LinkedList;
import java.util.Queue;

class Producer extends PubSub implements Runnable{

    @Override
    public void run() {
        synchronized(queue){
            if (queue.size() == 99){
                try { 
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            queue.add(2);
            try{
                Thread.sleep(1000);
            }
            catch (InterruptedException e){
                e.printStackTrace();
            }
            notify();
            }
        }       
}


class Consumer extends PubSub implements Runnable{

    @Override
    public void run() {
        synchronized(queue){
            if(queue.isEmpty()){
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }   
            }
            System.out.println(queue.poll());
        }

    }

}
public class PubSub {
    static Integer QUEUE_SIZE = 100;
    Queue<Integer> queue = new LinkedList<Integer>();
    public static void main(String[] args) {
        Producer producer = new Producer();
        Consumer consumer = new Consumer();
        Thread producerThread = new Thread(producer);
        Thread consumerThread = new Thread(consumer);
        producerThread.start();
        consumerThread.start();
        System.out.println("Started both the threads");
    }

}

我在 wait() 部分得到一个 java.lang.IllegalMonitorStateException。我想知道我在这里做错了什么。有什么想法吗？？

我得到的完整异常如下。

Exception in thread "Thread-1" Started both the threads
java.lang.IllegalMonitorStateException
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:502)
    at Consumer.run(PubSub.java:36)
    at java.lang.Thread.run(Thread.java:745)
Exception in thread "Thread-0" java.lang.IllegalMonitorStateException
    at java.lang.Object.notify(Native Method)
    at Producer.run(PubSub.java:23)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

您正在调用 wait() ，相当于 this.wait() , 但你没有拿着 this 的监视器.你在 queue 上拿着显示器.所以应该是queue.wait() . (与 notify() 相同)。