线程等待join(),wait()

最新推荐文章于 2023-09-06 17:22:20 发布

shonegg

最新推荐文章于 2023-09-06 17:22:20 发布

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分类专栏： Java 文章标签：线程

本文链接：https://blog.csdn.net/yoywow/article/details/52469771

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本文探讨了如何在多线程环境中使用join()和wait()方法来实现线程间的同步。场景描述中，线程3在启动后会并发执行线程1和2，并在自身运行5秒后等待它们结束。线程1运行8秒，线程2运行10秒。通过线程3调用wait()方法释放锁，使得线程1和2有机会执行并结束，最终由线程1和2唤醒线程3继续执行。

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场景1.有3线程个同时执行,怎样第3个线程等1和2线程退出之后,自己退出?

仔细想了下,join()可以阻塞当前线程

 Thread thread1 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            while (isRunning) {
                timer++;
                if (timer == 8) {
                    isRunning = false;
                }
                try {
                    sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.w("thread1", "thread1>>" + "" + timer);
            }
        }
    };


    Thread thread2 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            while (isRunning) {
                timer++;
                if (timer == 10) {
                    isRunning = false;
                }
                try {
                    sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.w("thread2", "thread2>>" + "" + timer);
            }
        }
    };

    Thread thread3 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            synchronized (mLock) {
                thread1.start();
                thread2.start();

                while (isRunning) {
                    timer++;
                    if (timer == 5) {
                        isRunning = false;
                    }
                    try {
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Log.w("thread3", "thread3>>" + timer);
                }

                try {
                    thread1.join();
                    thread2.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.w("thread3", "thread3>>" + "退出...");
            }
        }
    };

thread3.start();线程3启动,则会启动线程1和线程2,此时3个线程并发运行,为了区别开来,这里线程3运行5s后等待1和2结束,而线程1的生命周期是8s,线程2的生命周期是10s!

再看一个主动释放锁的例子

private Object mLock = new Object();

    Thread thread1 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            synchronized (mLock) {
                while (isRunning) {
                    timer++;
                    if (timer == 3) {
                        isRunning = false;
                    }
                    try {
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Log.w("thread1", "thread1>>" + timer);
                }
                if (!thread2.isAlive()){
                    mLock.notify();
                }
            }
            Log.e("thread1", "thread1 退出");
        }
    };


    Thread thread2 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            synchronized (mLock) {
                while (isRunning) {
                    timer++;
                    if (timer == 6) {
                        isRunning = false;
                    }
                    try {
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Log.w("thread2", "thread2>>" + timer);
                }
                if (!thread1.isAlive()){
                    mLock.notify();
                }
            }
            Log.e("thread2", "thread2 退出");

        }
    };

    Thread thread3 = new Thread() {
        private boolean isRunning = true;
        private int timer;

        @Override
        public void run() {
            synchronized (mLock) {
                thread1.start();
                thread2.start();
                try {
                    mLock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                while (isRunning) {
                    timer++;
                    if (timer == 5) {
                        isRunning = false;
                    }
                    try {
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Log.w("thread3", "thread3>>" + timer);
                }
            }
            Log.e("thread3", "thread3 退出");
        }
    };