@Test

    public void test3() throws InterruptedException {

        CountDownLatch countDownLatch = new CountDownLatch(5);

        ExecutorService executorService = Executors.newCachedThreadPool();

        for(int i = 0; i < 5; i++) {

            executorService.execute(new Task(countDownLatch));

        }

        countDownLatch.await();

        executorService.shutdown();

    }

    public static class Task implements Runnable {

        CountDownLatch countDownLatch;

        public Task(CountDownLatch countDownLatch) {

            this.countDownLatch = countDownLatch;

        }

        @Override

        public void run() {

            System.err.println("当前完成的任务数目：" + countDownLatch.getCount());

            countDownLatch.countDown();

        }

    }