线程通信

1. synchronized:线程A等待线程B于是就实现了通信
2. while轮询：这样会导致cpu的使用率较低，而且有内存可见性问题。因为线程每次都是去读本地线程栈的信息，因此如果别的线程改变了它也察觉不到。

public class ee {
    public static class RunThread extends Thread {

        volatile private boolean isRunning = true; // 加了volatile才具有可见性

        public boolean isRunning() {
            return isRunning;
        }

        public void setRunning(boolean isRunning) {
            this.isRunning = isRunning;
        }

        @Override
        public void run() {
            System.out.println("进入到run方法中了");
            while (isRunning == true) {
            }
            System.out.println("线程执行完成了");
        }
    }
    public static void main(String[] args) {
        try {
            RunThread thread = new RunThread();
            thread.start();
            Thread.sleep(1000);
            thread.setRunning(false);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

3. wait/notify
4. 管道机制，前面三种都是共享内存机制，管道应该是消息同行机制

线程通信