4-CyclicBarrier

与CountDownLatch功能相反。每执行一次则加一，直至累计到指定的数量。

public class CyclicBarrierDemo {
    public static void main(String[] args) throws BrokenBarrierException, InterruptedException {
        CyclicBarrier cyclicBarrier = new CyclicBarrier(7, () -> System.out.println("召唤神龙"));
        for (int i = 1; i <= 7; i++) {
            final int i1 = i;
            new Thread(() -> {
                System.out.println(Thread.currentThread().getName() + "收集到第 " + i1 + " 颗龙珠");
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }).start();
        }
    }
}

结果

Thread-0收集到第 1 颗龙珠
Thread-2收集到第 3 颗龙珠
Thread-1收集到第 2 颗龙珠
Thread-3收集到第 4 颗龙珠
Thread-4收集到第 5 颗龙珠
Thread-5收集到第 6 颗龙珠
Thread-6收集到第 7 颗龙珠
召唤神龙