public static void main(String [] args) throws BrokenBarrierException, InterruptedException {
        //建構函式傳了兩個引數,第一個是等待的執行緒數,第二個是當所有執行緒到達關卡點統一執行的任務
        CyclicBarrier cyclicBarrier = new CyclicBarrier(3, new Runnable() {
            @Override
            public void run() {
                System.out.println(
 
"嘿,還真一起執行了");
            }
        });

        //設定三個執行緒,每個阻塞不同的時間.
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(2000);
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } 
 
catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void
 
 run() {
                try {
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(3000);
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();

      /*下面注掉的這些的程式碼證明關卡可以重複使用.

      Thread.sleep(1000);

        Long startTime = System.nanoTime();

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(5000);
                    Long endTime = System.nanoTime() - startTime;

                    System.out.println("測試阻塞"+endTime);
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(2000);
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1000);
                    cyclicBarrier.await();
                    System.out.println("是否一起執行");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }
        }).start();
*/


    }