1.         CyclicBarrier cyclicBarrier = new CyclicBarrier(2);
    2.         Thread thread1 = new Thread(() -> {
    3.             System.out.println(Thread.currentThread().getName()+"[time]"+ new Date()+"[start]");
    4.             try {
    5.                 TimeUnit.SECONDS.sleep(1);
    6.             } catch (InterruptedException e) {
    7.                 throw new RuntimeException(e);
    8.             }
    9.             try {
    10.                 cyclicBarrier.await();
    11.             } catch (Exception e) {
    12.                 e.printStackTrace();
    13.             }
    14.             System.out.println(Thread.currentThread().getName()+"[time]"+ new Date()+"[end]");
    15.         },"thread-A");
    16.         Thread thread2 = new Thread(() -> {
    17.             System.out.println(Thread.currentThread().getName()+"[time]"+ new Date()+"[start]");
    18.             try {
    19.                 TimeUnit.SECONDS.sleep(2);
    20.             } catch (InterruptedException e) {
    21.                 throw new RuntimeException(e);
    22.             }
    23.             try {
    24.                 cyclicBarrier.await();
    25.             } catch (Exception e) {
    26.                 e.printStackTrace();
    27.             }
    28.             System.out.println(Thread.currentThread().getName()+"[time]"+ new Date()+"[end]");
    29.         },"thread-B");
    31.         thread1.start();
    32.         thread2.start();

    cyclicBarrier主要是用于在异步中，多个线程到达某一个时刻后，一起再做下面一件事。
    举例：多个人吃饭，可能出现先到后到，但是都是需要到达 人齐了之后，才会开始吃饭