带有执行器框架的可调用接口。为什么即使从调用方法返回后程序也没有退出

Question

我正在尝试了解执行程序框架的可调用接口。这是可行的，但我有点困惑为什么即使从调用方法返回后程序也不会退出。

代码：

CallableExample.java

package callable1;

import java.util.concurrent.Callable;

public class CallableExample implements Callable<String> {

    @Override
    public String call() throws Exception {
        // TODO Auto-generated method stub
        String s = Thread.currentThread().getName();
        for(int i = 0 ; i < 10 ; i++)
        {
            s += ""+i;
            System.out.println(s);
            Thread.sleep(1000);
        }

        return s;
    }
}

Tester.java

package callable1;

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

public class Tester {

    public static void main(String[] args) throws Exception
    {
        ExecutorService pool = Executors.newFixedThreadPool(5);
        Future<String> ftask = pool.submit(new CallableExample());

        System.out.println("getting result");
        System.out.println("----" + ftask.get());
        System.out.println("main over");
    }
}

Answer 1

java.util.concurrent.*的线程池就是这样设计的，所以你必须在你的执行器上调用shutdown()或shutdownNow()。否则程序不会停止。您可以在 javadocs 中找到方法之间的区别。

带有执行器框架的可调用接口。为什么即使从调用方法返回后程序也没有退出

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