Question

在java Thread中，我可以使用wait()和notify()轻松地在两个线程之间进行通信。

但是假设我有10个线程运行说T1到T10，我希望线程T2与线程T7进行通信。

我怎么能这样做？一些例子将不胜感激。

Answer 1

线程之间的通信可以通过wait / notify进行，但非常复杂（为了正确），尤其是当涉及两个以上的线程时。

BlockingQueue更现代的解决方案更适合Java中的线程间通信。

要使用它们，请在创建线程之前创建要在两个线程之间共享的队列。然后在创建时将队列传递给每个线程。然后他们都保持队列，一个写入，另一个读取。

public class TwoThreads {

    public static void main(String args[]) throws InterruptedException {
        System.out.println("TwoThreads:Test");
        new TwoThreads().test();
    }

    // The end of the list.
    private static final Integer End = -1;

    static class Producer implements Runnable {

        final BlockingQueue<Integer> queue;

        public Producer(BlockingQueue<Integer> queue) {
            this.queue = queue;
        }

        @Override
        public void run() {
            try {
                for (int i = 0; i < 1000; i++) {
                    queue.add(i);
                    Thread.sleep(1);
                }
                // Finish the queue.
                queue.add(End);
            } catch (InterruptedException ex) {
                // Just exit.
            }
        }

    }

    static class Consumer implements Runnable {

        final BlockingQueue<Integer> queue;

        public Consumer(BlockingQueue<Integer> queue) {
            this.queue = queue;
        }

        @Override
        public void run() {
            boolean ended = false;
            while (!ended) {
                try {
                    Integer i = queue.take();
                    ended = i == End;
                    System.out.println(i);
                } catch (InterruptedException ex) {
                    ended = true;
                }
            }
        }

    }

    public void test() throws InterruptedException {
        BlockingQueue<Integer> queue = new LinkedBlockingQueue<>();
        Thread pt = new Thread(new Producer(queue));
        Thread ct = new Thread(new Consumer(queue));
        // Start it all going.
        pt.start();
        ct.start();
        // Wait for it to finish.
        pt.join();
        ct.join();
    }

}

Answer 2

这是示例

public static void main(String[] args) throws Exception {
    final Object[] monitors = new Object[10];
    final Thread[] threads = new Thread[10];
    for (int i = 0; i < 10; i++) {
        final int num = i;
        Thread t = new Thread() {
            @Override
            public void run() {
                final Object mon = monitors[num];
                try {
                    synchronized (mon) {
                        mon.wait();
                    }
                } catch (InterruptedException ex) {
                    Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, ex);
                }
                System.out.println("Hello, world from thread " + num);
            }
        };
        Object o = new Object();
        threads[i] = t;
        monitors[i] = o;
        t.start();
    }

    final Object mon = monitors[5];
    synchronized (mon) {
        mon.notify();
    }
    Thread.sleep(10000);
}

Java线程通信

2 个答案: