我可以使用Callable线程没有ExecutorService吗？ [英] Can I use Callable threads without ExecutorService?

问题描述

我可以使用Callable线程而不使用ExecutorService吗？我们可以使用Thread的Runnable和子类的实例，而不使用ExecutorService，这段代码正常工作。但是这段代码是一致的：

Can I use Callable threads without ExecutorService? We can use instances of Runnable and subclasses of Thread without ExecutorService and this code works normally. But this code works consistently:

public class Application2 {

    public static class WordLengthCallable implements Callable {
        public static int count = 0;
        private final int numberOfThread = count++;

        public Integer call() throws InterruptedException {
            int sum = 0;
            for (int i = 0; i < 100000; i++) {
               sum += i;
            }
            System.out.println(numberOfThread);
            return numberOfThread;
       }
   }
   public static void main(String[] args) throws InterruptedException {
       WordLengthCallable wordLengthCallable1 = new WordLengthCallable();
       WordLengthCallable wordLengthCallable2 = new WordLengthCallable();
       WordLengthCallable wordLengthCallable3 = new WordLengthCallable();
       WordLengthCallable wordLengthCallable4 = new WordLengthCallable();
       wordLengthCallable1.call();
       wordLengthCallable2.call();
       wordLengthCallable3.call();
       wordLengthCallable4.call();
       try {
           Thread.sleep(1000);
       } catch (InterruptedException e) {
          e.printStackTrace();
      }
      System.exit(0);
  }
}

使用ExecutorService代码可以处理几个线程。

接口通常是创建的，但是我的错误是在哪里？

With ExecutorService the code works with few threads. Where are my mistakes?

推荐答案

您可以提交 Runnable 它到 ExecutorService ，或者将它传递给 Thread 的构造函数，或者您可以调用其 run（）方法直接像调用任何接口方法，而不涉及多线程。还有更多的用例，例如。 AWT EventQueue.invokeLater（Runnable），因此不要期望列表完成。

Given a Runnable you can submit it to an ExecutorService, or pass it to the constructor of Thread or you can invoke its run() method directly like you can invoke any interface method without multi-threading involved. And there are more use cases, e.g. AWT EventQueue.invokeLater(Runnable) so never expect the list to be complete.

c> Callable ，你有相同的选项，所以重要的是要强调，不像你的问题所暗示的，直接调用 call（）任何多线程。

Given a Callable, you have the same options, so it’s important to emphasize that, unlike your question suggests, invoking call() directly does not involve any multi-threading. It just executes the method like any other ordinary method invocation.

由于没有构造函数 Thread（Callable）使用不带 ExecutorService 的可调用代码：

Since there is no constructor Thread(Callable) using a Callable with a Thread without an ExecutorService requires slightly more code:

FutureTask<ResultType> futureTask = new FutureTask<>(callable);
Thread t=new Thread(futureTask);
t.start();
// …
ResultType result = futureTask.get(); // will wait for the async completion

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