Question

            public void aMethod(){
              new Thread(new Runnable() {

                public void run() {
                   int decide = JOptionPane.showConfirmDialog(null, confirmName?, JOptionPane.YES_NO_OPTION);
                }
            }).start();
            System.out.println("Number of decison " + decide); //Can't find symbol "decide"
               }

---

JOptionPane can’t run without being put to a thread(I don’t know why). Yet when put it to a thread, I can’t get the varible decide from that.
P/s: This is a method in callbackImplement Java RMI.
Thank you. happy new year 😛

Answer 1

You can define custom fields in your Runnable subclass and pass them through the constructor:

public class MyRunnable implements Runnable {
  private int decide;

  public MyRunnable(int decide) {
    this.decide = decide;
  }

  public void run() {
    ...
  }
}

As for why you need to invoke Swing methods on their own thread, you can read this article: Threads and Swing. In fact, you shouldn’t be creating your own thread but instead just schedule it on the Swing event dispatch thread:

SwingUtilities.invokeLater(new MyRunnable(decide));