无法确定为什么在 class 中以匿名 classes 实现多个可运行接口时 CountDownLatch 无法正常工作

Question

如果我定义一个 class Team 并在 class 中实现两个 runnable interfaces，我不会在程序中到达任务 [= =15=] 和 team2 结束。但是，如果我像在 WorkerOne 中一样直接在 class 中实现 runnable，我将到达它打印任务的行 WorkerOne 结束。我不明白为什么 team1 和 team2 的任务永远不会完成并且应用程序不会停止。我在下面包含了代码和控制台输出。我会很感激任何想法或想法。谢谢。

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

class WorkerOne implements Runnable {
    private CountDownLatch latch;

    public WorkerOne(CountDownLatch latch) {
        this.latch = latch;
    }

    @Override
    public void run() {
        System.out
                .println("[Tasks by WorkerOne : ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + " START");
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        latch.countDown();
        System.out.println("[Tasks by WorkerOne : ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + " END");

    }

}

class Team {
    private CountDownLatch latch;

    Runnable team1 = new Runnable() {
        public void run() {
            System.out.println("[Tasks by team1: ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + "START");
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            latch.countDown();
            System.out.println("[Tasks by team1 : ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + " END");

        }
    };

    Runnable team2 = new Runnable() {
        public void run() {
            System.out.println("[Tasks by team2 : ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + "START");
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            latch.countDown();
            System.out.println("[Tasks by team2 : ]" + " :: " + "[" + Thread.currentThread().getName() + "]" + " END");

        }
    };
}

public class Demo {

    public static void main(String[] args) {
        CountDownLatch latch = new CountDownLatch(3);
        ExecutorService service = Executors.newFixedThreadPool(3);
        service.submit(new WorkerOne(latch));
        service.submit(new Team().team1);
        service.submit(new Team().team2);
        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Tasks completed......");
    }
}

控制台输出为：

[Tasks by WorkerOne : ] :: [pool-1-thread-1] START
[Tasks by team1: ] :: [pool-1-thread-2]START
[Tasks by team2 : ] :: [pool-1-thread-3]START
[Tasks by WorkerOne : ] :: [pool-1-thread-1] END

Answer 1

问题是因为你

    service.submit(new Team().team1);
    service.submit(new Team().team2);

latch 是 Team 的私有成员，您已经创建了 Team 的两个实例，每个都有自己的 latch。

我不确定你为什么要这样做，但我相信你想要

    Team team = new Team();
    service.submit(team.team1);
    service.submit(team.team2);

Answer 2

Team class' 闩锁变量从未初始化。我怀疑您打算像在 WorkerOne class.

中那样执行此初始化，但忘记了

执行您发布的代码会使 Team runnable 在 latch 字段上调用 countDown() 时抛出 NullPointerException。主线程永远等待它的 CountDownLatch 因为它永远不会倒数到 0.

无法确定为什么在 class 中以匿名 classes 实现多个可运行接口时 CountDownLatch 无法正常工作

Unable to determine why CountDownLatch is not functioning when multiple runnable interfaces are implemented in anonymous classes inside a class

java

multithreading

countdownlatch