CountDownLatch的使用

/*
  減法計數器
*/
public class Test1 {
    public static void main(String[] args) throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(10);//一共減10次

        for (int i = 1; i < 11; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName() + " Go Out");
                countDownLatch.countDown();//每次減一
            }, String.valueOf(i)).start();
        }
        countDownLatch.await();//等待計數器歸零 再繼續向下執行
        System.out.println("Close Door");
    }
}
 

CyclicBarrier的使用

/*
  加法計數器
*/
public class Test {
    public static void main(String[] args) {
        CyclicBarrier cyclicBarrier = new CyclicBarrier(7, ()->{
            System.out.println("集齊了龍珠");
        });

        for (int i = 1; i < 8; i++) {
            int temp = i;
            new Thread(/*()->{
                System.out.println(Thread.currentThread().getName()+"收集第"+ temp +"顆龍珠");
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            }*/
                    new Runnable() {
                        @Override
                        public void run() {
                            System.out.println(Thread.currentThread().getName()+"收集第"+ temp +"顆龍珠");
                            try {
                                cyclicBarrier.await();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            } catch (BrokenBarrierException e) {
                                e.printStackTrace();
                            }
                        }
                    }, String.valueOf(temp)).start();
        }
    }
}
 

Semaphore的使用

/*
  執行緒數量限制
*/
public class Test3 {
    public static void main(String[] args) {
        //執行緒數量  限流用
        Semaphore semaphore = new Semaphore(3);

        for (int i = 1; i < 7; i++) {
            new Thread(()->{
                try {
                    semaphore.acquire();//搶到車位
                    System.out.println(Thread.currentThread().getName()+"搶到了車位");
                    TimeUnit.SECONDS.sleep(1);
                    System.out.println(Thread.currentThread().getName()+"離開了車位");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                    semaphore.release();//離開車位
                }
            }, String.valueOf(i)).start();
        }
    }
}