java面试-CountDownLatch、CyclicBarrier、Semaphore谈谈你的理解

一、CountDownLatch

主要用来解决一个线程等待多个线程的场景，计数器不能循环利用

public class CountDownLatchDemo {

    public static void main(String[] args) throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(6);
        for (int i = 1; i <= 6; i++) {
            new Thread(() -> {
                System.out.println(Thread.currentThread().getName() + " 上完自习，离开教室");
                countDownLatch.countDown();
            }, String.valueOf(i)).start();
        }
        countDownLatch.await();
        System.out.println(Thread.currentThread().getName() + " 班长最后关门走人");
    }
}

二、CyclicBarrier

是一组线程之间互相等待，计数器可以循环利用。