java併發編程學習之線程的生命週期-join(四）

定義

等待該線程終止，好比A線程調用了B線程的join，那麼A線程要等到B線程執行完後，才能夠繼續執行。

示例

public class JoinDemo {
    static class JoinThread1 implements Runnable {
        Thread thread;

        public JoinThread1(Thread thread) {
            this.thread = thread;
        }

        @Override
        public void run() {
            System.out.println("thread1 start");
            try {
                thread.join();
                System.out.println("thread1 end");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    static class JoinThread2 implements Runnable {
        @Override
        public void run() {
            System.out.println("thread2 start");
            try {
                Thread.sleep(10000);
                System.out.println("thread2 end");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        JoinThread2 joinThread2 = new JoinThread2();
        Thread thread2 = new Thread(joinThread2);
        JoinThread1 joinThread1 = new JoinThread1(thread2);
        Thread thread1 = new Thread(joinThread1);

        thread1.start();
        thread2.start();
    }
}

運行結果以下：

線程1執行的時候，調用線程2的join，線程1不休眠，線程2休眠了10秒，從結果看出來，線程2執行完後，線程1才執行完。