java 线程：当一个线程完成任务时停止所有线程

Question

我用线程池创建了两个线程，如果其中一个完成了，则需要停止其他线程。 我怎样才能实现？

我的想法是使用AtomicBoolean或者CountDownLatch来实现。我的代码如下：

import com.google.common.util.concurrent.ThreadFactoryBuilder;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicBoolean;

public class Test {
public static void main(String[] args) {
    //Thread Pool
    ThreadFactory namedThreadFactory = new ThreadFactoryBuilder().setNameFormat("demo-pool-%d").build();
    ExecutorService executorService = new ThreadPoolExecutor(6, 10, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingDeque<Runnable>(1024), namedThreadFactory, new ThreadPoolExecutor.AbortPolicy());

    AtomicBoolean atomicBool = new AtomicBoolean(false);

    System.out.println("start");
    for (int i = 0; i < 2; i++) {
        //If any threads are executed, all threads end immediately
        if (atomicBool.get() == true) {
            executorService.shutdownNow();
        }

        executorService.execute(() -> {
            System.out.println(Thread.currentThread().getName());
            //do something
            //....
            atomicBool.set(true);
        });
    }

    if (atomicBool.get() == true) {
        executorService.shutdownNow();
    }
    System.out.println("end");
}}

但是两个线程都完成了，结果如下：

start
end
demo-pool-0
demo-pool-1

我应该怎么办？

Answer 1

除了使用AtomicBoolean ，您还可以使用CountDownLatch的实例并将其传递给每个线程以等待达到倒计时值（在您的示例中，锁存器将初始化为 1）。 主线程在锁存器上调用await()并将阻塞直到至少一个线程调用countDown() 。

https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/util/concurrent/CountDownLatch.ZFC35FDC70D5FC69A269883A822C7