CountDownLatch 锁计数器的使用

 public static void testThread(){
        CountDownLatch countDownLatch = new CountDownLatch(2);
        System.out.println("MainTest.testThread,开启两个子线程：");
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("testThread,开启子线程1：");
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("testThread,子线程1结束");
                countDownLatch.countDown();
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("testThread,开启子线程2：");
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("testThread,子线程2结束");
                countDownLatch.countDown();
            }
        }).start();

        try {
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("MainTest.testThread,主线程结束");
    }

结果：

MainTest.testThread,开启两个子线程：
testThread,开启子线程1：
testThread,开启子线程2：
testThread,子线程1结束
testThread,子线程2结束
MainTest.testThread,主线程结束