在两个线程之间进行通信 [英] Communicating between two threads

问题描述

我有一个帖子， A 有一个列表。 List包含一些对象。现在我想设计一个机制，通过该机制，我可以向线程发送一些消息 A 。

I have a thread, A which has a list. List holds some objects. Now I want to design a mechanisim by which I can send some message to thread A.

线程A 在循环中运行（它不等待或休眠）。
其他一些线程， B ，向线程 A 和线程发送一些消息A 清空所有队列。

Thread A runs in a loop (it does not wait or sleep). Some other thread, B, sends some message to thread A and thread A empties all its queues.

如何在线程之间发送消息？

How can I send messages between threads?

class A extends Thread {
    List<Object> objs = something; //Init it
    void run() {
        while(true) {
            //Body which works on objects.
            //After receiving an external message, "A" should perform some action, for example, empty objects.
        }
    }
}

编辑：
我可以这样做吗？

Can I do it like this?

class A extends Thread {
    List<Object> objs = something; //Init it
    Boolean flag = false;

    public void setFlag(boolean value) {
        synchronized(flag) {
            this.flag = value;
        }
    }

    public void getFlag() {
        synchronized(flag) {
            return this.flag;
        }
    }

    void run() {
        while(true) {
            //Body which works on objects.
            //After receiving an external message, A should perform some action, for example, empty objects.
            if (getFlag == true)
                //Empty list
        }
    }
}

推荐答案

你可以有一个 BlockingQueue 。其他线程会将消息放入队列。作为 while（true）循环的一部分，线程 A 将 民意调查 队列并处理已到达的任何消息。

You could have a BlockingQueue of message objects. Other threads would place messages onto the queue. As part of the while(true) loop, thread A would poll the queue and process any messages that have arrived.

代码：

class A extends Thread{
 List<Object>  objs = something ;//init it
 BlockingQueue<Message> queue = new LinkedBlockingQueue<Message>();
 void run(){
     while(true){
       Message msg;
       while ((msg = queue.poll()) != null) {
         // process msg
       }
       // do other stuff
     }
   }
}

其他线程现在可以调用 queue.put （）将消息发送到线程 A 。

Other threads can now call queue.put() to send messages to thread A.

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