多线程场景题：有5个人，在那赛跑，请你设计一个多线程的裁判程序给出他们赛跑的结果顺序，5个人的速度随机处理

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

public class CountDownLatchExample1 {

    //volatile 关键字确保多线程环境下的可见性
    public volatile static Integer num = 0;
    public static String[] res = new String[5];
    private static final int threadCount = 5;

    public static void main(String[] args) throws InterruptedException {
        ExecutorService threadPool = Executors.newFixedThreadPool(5);
        final CountDownLatch countDownLatch = new CountDownLatch(threadCount);
        Random random = new Random();
        for (int i = 0; i < threadCount; i++) {
            final int threadnum = i;
            threadPool.execute(() -> {
                try {
                    int sleepTime = random.nextInt(401) + 100;
                    Thread.sleep(sleepTime);
                    res[num++] = "运动员" + (threadnum + 1) + "消耗的时间为" + sleepTime;
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                } finally {
                    countDownLatch.countDown();
                }
            });
        }
        countDownLatch.await();
        threadPool.shutdown();
        for (String re : res) {
            System.out.println(re);
        }
    }
}

await() 用来等待计数归零

countDown () 用来让计数减一