场景描述：

模拟10个线程，并发执行，最后汇总结果

代码：

package com.jf.service.market.impl;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class CountDownLatchTest {
    
   public static void main(String[] args) {
        int num = 10;
        long time = System.currentTimeMillis();
        ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
        final CountDownLatch latch = new CountDownLatch(num);
        for (int i = 0; i < 10; i++) {
            cachedThreadPool.execute(new Runnable() {
                public void run() {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(" End=== Thread："+Thread.currentThread().getId()); 
                    latch.countDown();
                }
            });
        }
        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("总共耗时:" + (System.currentTimeMillis()-time));
        cachedThreadPool.shutdown();
    }
}

结果展示：

 End=== Thread：10
 End=== Thread：15
 End=== Thread：17
 End=== Thread：16
 End=== Thread：14
 End=== Thread：13
 End=== Thread：12
 End=== Thread：9
 End=== Thread：11
 End=== Thread：18
总共耗时:1008