java 多线程之 CountDownLatch

CountDownLatch

闭锁是一种同步工具类，可以延迟线程的进度直到其到达终止状态；

countDwon 方法递减计数器

await 方法等待计数器到达 0 ，为 0 表示所有需要等待的事件都已经发生

代码

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

public class CountDownLatchDemo implements Runnable{
    private static CountDownLatch end = new CountDownLatch(10);
    private static CountDownLatchDemo demo = new CountDownLatchDemo();

    @Override
    public void run() {
        try {
            Thread.sleep(new Random().nextInt(10)*1000);
            System.out.println("check complete!");
            end.countDown(); //通知 CountDownLatch 一个任务完成，执行 countDown
        }catch (InterruptedException e) { //中断异常
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        ExecutorService exec = Executors.newFixedThreadPool(10);
        for (int i=0;i<10;i++){
            exec.submit(demo);
        }
        //等待检查
        end.await();
        //发射火箭
        System.out.println("Fire !");
        exec.shutdown();
    }
}