Question

与普通线程不同，callable是一个允许返回变量的线程，

我的问题是可以使用可调用线程实现timertask吗？如果是的话，代码是如何工作的？

由于Timer任务正在使用void run（）代码，我如何使用可调用对象的timer任务，因为可调用线程使用了对象call（），而不是void run（）

例如，我需要实现将返回布尔值的线程（可调用线程可以返回一个布尔值），并且我需要每隔10秒定期运行该线程进程（这就是为什么我要实现计时器任务）

public class test extends TimerTask implements Callable<Boolean>{

public void run()  //from timer task thread
{
  //timer task will only implement time task in here
  // i cant run my task here because my task have return boolean.
  // note that run() only accept void task.
}

public boolean call{  // from callable thread
  // i implement code here and end result will return true or false 
  // i have no idea how to instruct timer task
  // to keep execute my code here periodically

  //task processed . . .
  Boolean status = true;


return status;
}

答案

我认为不可能或非常不鼓励在可调用线程上实现计时器任务

Answer 1

您需要一个Future对象来使用ExecutorService读取结果。

查看示例：

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CallableTimer {

public static void main(String[] args) {
    MyCallableThread myThread = new MyCallableThread();
    Timer timer = new Timer();
    MyTask theTask = new MyTask();
    theTask.addThread(myThread);

    // Start in one second and then every 10 seconds
    timer.schedule( theTask , 1000, 10000 );
}
}

class MyTask extends TimerTask
{
MyCallableThread timerThread = null;
ExecutorService executor;

public MyTask() {
    executor = Executors.newCachedThreadPool();
}

public void addThread ( MyCallableThread thread ) {
    this.timerThread = thread;
}

@Override
public void run()
{
    System.out.println( "MyTask is doing something." );
    if ( timerThread != null ) {
        boolean result;
        Future<Boolean> resultObject = executor.submit( timerThread );

        try {
            result = resultObject.get();
            System.out.println( "MyTask got " + result + " from Thread.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    } else {
        System.out.println( "No Thread set." );
    }
}

}

class MyCallableThread implements Callable<Boolean> {

@Override
public Boolean call() throws Exception {
    Boolean status = true;
    System.out.println( "MyCallableThread is returning " + status + ".");
    return status;

}
}

是否可以在java中使用Callable Thread实现计时器任务？

1 个答案: