如何从Java的内部Thread Runnable方法获取返回值? [英] How do i get returned value from inner Thread Runnable method in Java?

问题描述

如何使用isFinish()将Status与CallMe()分配为返回值true?

How do i assign Status with CallMe() using isFinish() to have returned value true?

public static boolean isFinish ()
{    
  boolean Status = false;
  new Thread(new Runnable()
  {
    public void run()
    {
      /* This shell return true or false 
       * How do you keep it in Status
       */
      CallMe(); 
    }
  }).start();

  /* How can i get the true or false exactly from CallMe? here */
  return Status;
}

public static boolean CallMe()
{
  /* some heavy loads ... */
  return true;
}

推荐答案

有两种方法. 第一种是使用将来的计算结果，第二种是使用共享变量. 我认为第一种方法比第二种方法干净得多，但是有时您也需要将值推入线程.

There are two ways of doing this. The first is to use a future computation result and the other is to have a shared variable. I think that the first method is much cleaner than the second, but sometimes you need to push values to the thread too.

• 使用RunnableFuture.

FutureTask实现RunnableFuture.因此，您创建了一个任务，该任务一旦执行便会具有一个值.

FutureTask implements a RunnableFuture. So you create that task which, once executed, will have a value.

RunnableFuture f = new FutureTask(new Callable<Boolean>() {
  // implement call
});
// start the thread to execute it (you may also use an Executor)
new Thread(f).start();
// get the result
f.get();

• 使用持有人课程

您创建一个包含值的类，并共享对该​​类的引用.您可以创建自己的类，也可以简单地使用AtomicReference. 持有人类别，是指具有公开可修改属性的类别.

You create a class holding a value and share a reference to that class. You may create your own class or simply use the AtomicReference. By holder class, I mean a class that has a public modifiable attribute.

// create the shared variable
final AtomicBoolean b = new AtomicBoolean();
// create your thread
Thread t = new Thread(new Runnable() {
  public void run() {
    // you can use b in here
  }
});
t.start();
// wait for the thread
t.join();
b.get();

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