CountDownLatch和 CyclicBarrier的使用

public class CountDownLatchDemo {
    public static void main(String[] args) {
        /**
         * 传入的8会赋值给CountDowmLatch内部的Sync的state
         */
        CountDownLatch countDownLatch = new CountDownLatch(8);
        new Thread(()->{
            try {
                //只有等到CountDowmLatch内部的Sync的state==0才会被唤醒
                countDownLatch.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("800米比赛结束，准备清空跑道并继续跨栏比赛");
        }).start();
        for (int i = 0; i < 8; i++) {
            int finalI = i;
            new Thread(()->{
                try {
                    Thread.sleep(finalI * 1000L);
                    System.out.println(Thread.currentThread().getName()+"到达终点");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    //每执行一个线程countDownLatch中的state减1
                    countDownLatch.countDown();
                }
            }).start();
        }
    }
}

public class CyclicBarrierDemo {
    public static void main(String[] args) {
        //当在这个cyclicBarrier等待的线程达到8个时，才允许线程会唤醒所有等待在cyclicBarrier上的线程继续执行
        CyclicBarrier cyclicBarrier = new CyclicBarrier(8);
        for (int i = 0; i < 8; i++) {
            int finalI = i;
            new Thread(() -> {
                try {
                    Thread.sleep(finalI * 1000L);
                    System.out.println(Thread.currentThread().getName() + "准备就绪");
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() +" 开始比赛");
            }).start();
        }
    }
}