package concurrent;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * Auth: zhouhongliang * Date：2019/8/1 * CountDownLatch倒计时锁 * 阻塞主线程，等子线程全部执行完之后主线程继续执行 * */public class CountDownLatchDemo { public static int count = 0; /** * 计算1至10000的和 * @param args */ public static void main(String[] args) throws InterruptedException { //定义一个缓冲线程池 ExecutorService executorService = Executors.newCachedThreadPool(); //定义一个倒计时锁 CountDownLatch countDownLatch = new CountDownLatch(10000); for (int i=1;i<=10000;i++){ final int index = i; //多个线程执行 executorService.execute(()->{ synchronized (CountDownLatchDemo.class){ try { count += index; } catch (Exception e) { e.printStackTrace(); } finally { //计数器减1 countDownLatch.countDown(); } } }); } //线程阻塞，知道countDownLatch计数值=0 countDownLatch.await(); System.out.println(count); //关闭线程池 executorService.shutdown(); }}

输出结果：50005000