CountDownLatch的例子：

public static void main(String[] args) {
        CountDownLatch countDownLatch = new CountDownLatch(6);
        for (int i = 0; i < 7; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName() +"=====卷王下班了");
                countDownLatch.countDown();
            },i+"").start();
        }
        try {
            countDownLatch.await();
            System.out.println(Thread.currentThread().getName() +" 物业关门");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

CyclicBarrier例子：

public static void main(String[] args) {

        CyclicBarrier cyclicBarrier = new CyclicBarrier(7,()->{
            System.out.println(Thread.currentThread().getName()+"开始出发了...");
        });
        for (int i = 0; i < 7; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"===卷王了，");
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }

            },String.format("%s",i)).start();
        }

    }

Semaphore例子：

 public static void main(String[] args) {
        // 抢车位
        Semaphore semaphore = new Semaphore(3);
        for (int i = 0; i < 9; i++) {
            new Thread(()->{
                try {
                    semaphore.acquire();
                    System.out.println(Thread.currentThread().getName()+"... 开进来了");
                    try {
                        TimeUnit.SECONDS.sleep(3);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName()+"... 开走了");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                    semaphore.release();
                }
            },String.valueOf(i)).start();
        }
    }