java基本教程之join方法详解 java多线程教程

public final synchronized void join(long millis)
throws InterruptedException {
    long base = System.currentTimeMillis();
    long now = 0;

    if (millis < 0) {
        throw new IllegalArgumentException("timeout value is negative");
    }

    if (millis == 0) {
        while (isAlive()) {
            wait(0);
        }
    } else {
        while (isAlive()) {
            long delay = millis - now;
            if (delay <= 0) {
                break;
            }
            wait(delay);
            now = System.currentTimeMillis() - base;
        }
    }
}

    public static void main(String[] args){
        try {
            ThreadA t1 = new ThreadA("t1"); // 新建“线程t1”

            t1.start();                     // 启动“线程t1”
            t1.join();                        // 将“线程t1”加入到“主线程main”中，并且“主线程main()会等待它的完成”
            System.out.printf("%s finish\n", Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    static class ThreadA extends Thread{

        public ThreadA(String name){
            super(name);
        }
        public void run(){
            System.out.printf("%s start\n", this.getName());

            // 延时操作
            for(int i=0; i <1000000; i++)
               ;

            System.out.printf("%s finish\n", this.getName());
        }
    }
}