Question

我有一个Thread和一个Swingworker。 Swingworker从Thread获取值并在JPanel中发布它们。

由于我不希望线程继续直到Swingworker取值，我在无限循环中停止它，但是当我更改布尔值时，线程不会继续。

这是问题的一个例子：

Swingworker Class

public class Worker extends SwingWorker<Void,int> 
{
    Mail m;
    MyJPanel jp;

    public Worker(Mail m, MyJPanel jp)
    {
       this.m = m;
       this.jp = jp;
    }

protected Void doInBackground() throws Exception 
    {
            int letter;


            while(!m.getEnd())
            {


                letter = m.getMail();

                publish(letter);

                Thread.sleep(2000);
            }

            return null;
    }

    protected void process(List<int> chunks) 
    {
         for (int number : chunks) 
         {
              jp.setTextArea("Letter n " + number + " arrived");
         }
     }

}

邮件类

public class Mail extends Thread
{
  private int delivery;
  private int num;
  private boolean stop = true;
  private boolean end = false;

public Mail(int num)
{
       this.num = num;
}

public void run()
{
       for(int i = 0; i < num;i++)
      {
          doDelivery(i);
      }
     end = true;
}
public void doDelivery(int x)
{
     delivery = x;

     System.out.println("Delivery awaits");

     while(stop);

     System.out.println("Delivery completed");

     stop = true;
}
public int getMail()
{
    System.out.println("Taking the mail"); 

    stop = false;

    return delivery;

}
public boolean getEnd()
{
   return end;
}

线程启动的部分代码

// being "panel" an extension of JPanel

      public void actionPerformed(ActionEvent e) 
        {
           if(e.getActionCommand().equals("start"))
           {

                   int num = panel.getNum();

                   Mail m = new Mail(num);
                   Worker worker = new Worker(m,panel);

                   m.start();
                   worker.execute();

               }
           }

控制台中的输出为：

Delivery awaits
Taking the mail
//Span of 2 seconds
Taking the mail
Taking the mail

在textArea中是

Letter n 0 arrived
Letter n 0 arrived
Letter n 0 arrived

我从未看到“交付已完成”，因此即使Swingworker正在更改循环布尔值，线程也不会离开它。为什么呢？

Answer 1

我用信号量替换了bool值，现在Mail类看起来像这样。

public class Mail extends Thread
{
  private int delivery;
  private int num;
  private Semaphore sem = new Semaphore(0,true);
  private boolean end = false;

public Mail(int num)
{
       this.num = num;
}

public void run()
{
       for(int i = 0; i < num;i++)
      {
          doDelivery(i);
      }
     end = true;
}
public void doDelivery(int x)
{
     delivery = x;

     System.out.println("Delivery awaits");

      try {

           sem.acquire();

       } catch (InterruptedException ex) {};

     System.out.println("Delivery completed");

}
public int getMail()
{
    System.out.println("Taking the mail"); 

    sem.release();

    return delivery;

}
public boolean getEnd()
{
   return end;
}

这似乎有效，但如果没有，我会更新。

线程中的布尔值不会改变

1 个答案: