多线程同步执行，CountDownLatch使用

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

class CountDownLatchTests {

    public static void main(String[] args) throws InterruptedException {
        //相当于计数器
        CountDownLatch countDownLatch = new CountDownLatch(5);
        //计数器总数是5,当减少为0,任务才继续向下执行
        for (int i = 0; i < 10; i++) {
            int finalI = i;
            new Thread(() -> {
                try {
                    TimeUnit.SECONDS.sleep(finalI);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() + "-->start");
                countDownLatch.countDown();
            }).start();
        }
        countDownLatch.await();
        System.out.println("main线程继续向下执行");
    }
}

执行结果