目录

• 前言
• CountDownLatch
  • 例子
• CyclicBarrier
  • 构造函数
  • 例子
• 两者区别

 	//创建初始化3个线程的线程池    private ExecutorService                    threadPool     = Executors.newFixedThreadPool(3);    //保存每个学生的平均成绩    private ConcurrentHashMap<String, Integer> map            = new ConcurrentHashMap<>();    private CountDownLatch                     countDownLatch = new CountDownLatch(3);    private void count() {        for (int i = 0; i < 3; i++) {            threadPool.execute(() -> {                //计算每个学生的平均成绩,代码略()假设为60~100的随机数                int score = (int) (Math.random() * 40 + 60);                try {                    Thread.sleep(Math.round(Math.random() * 1000));                } catch (InterruptedException e) {                    e.printStackTrace();                }                map.put(Thread.currentThread().getName(), score);                System.out.println(Thread.currentThread().getName() + "同学的平均成绩为" + score);                countDownLatch.countDown();            });        }        this.run();        threadPool.shutdown();    }    @Override    public void run() {        try {            countDownLatch.await();        } catch (InterruptedException e) {            e.printStackTrace();        }        int result = 0;        Set<String> set = map.keySet();        for (String s : set) {            result += map.get(s);        }        System.out.println("三人平均成绩为:" + (result / 3) + "分");    }    public static void main(String[] args) throws InterruptedException {        long now = System.currentTimeMillis();        CyclicBarrier1 cb = new CyclicBarrier1();        cb.count();        Thread.sleep(100);        long end = System.currentTimeMillis();        System.out.println(end - now);    }

	//创建初始化3个线程的线程池    private ExecutorService                    threadPool     = Executors.newFixedThreadPool(3);    //创建3个CyclicBarrier对象,执行完后执行当前类的run方法    private CyclicBarrier                      cb             = new CyclicBarrier(3, this);    //保存每个学生的平均成绩    private ConcurrentHashMap<String, Integer> map            = new ConcurrentHashMap<>();    private void count() {        for (int i = 0; i < 3; i++) {            threadPool.execute(() -> {                //计算每个学生的平均成绩,代码略()假设为60~100的随机数                int score = (int) (Math.random() * 40 + 60);                try {                    Thread.sleep(Math.round(Math.random() * 1000));                } catch (InterruptedException e) {                    e.printStackTrace();                }                map.put(Thread.currentThread().getName(), score);                System.out.println(Thread.currentThread().getName() + "同学的平均成绩为" + score);                try {                    //执行完运行await(),等待所有学生平均成绩都计算完毕                    cb.await();                } catch (InterruptedException | BrokenBarrierException e) {                    e.printStackTrace();                }            });        }        threadPool.shutdown();    }    @Override    public void run() {        int result = 0;        Set<String> set = map.keySet();        for (String s : set) {            result += map.get(s);        }        System.out.println("三人平均成绩为:" + (result / 3) + "分");    }    public static void main(String[] args) throws InterruptedException {        long now = System.currentTimeMillis();        CyclicBarrier1 cb = new CyclicBarrier1();        cb.count();        Thread.sleep(100);        long end = System.currentTimeMillis();        System.out.println(end - now);    }