SwingUtilites: how to return values from another t

Question

I am trying to make an application in Java. To make Swing work correctly, I did this:

public static void main(String[] array){ 

String outerInput;
SwingUtilities.invokeLater(new Runnable(){
    @Override
    public void run() {
        // I want this string input.
        String input = JOptionPane.showInputDialog(
            null,"Stop ?", JOptionPane.QUESTION_MESSAGE);  
});
// How can I get this input value in String outerInput?
}

How would I get this input string in my main body?

Answer 1

I suggest using the observer/observable pattern for this, perhaps with a PropertyChangeListener. Then your Swing app will be able to notify any and all listeners if the critical variable(s) state changes.

For example:

import java.awt.*;
import java.beans.*;
import javax.swing.*;
import javax.swing.event.*;

public class ListenToSwing  {
   public static final String STATE = "state";
   private static final int STATE_MAX = 10;
   private static final int STATE_MIN = -10;
   private JPanel mainPanel = new JPanel();
   private int state = 0;
   private JSlider slider = new JSlider(STATE_MIN, STATE_MAX, 0);

   public ListenToSwing() {
      mainPanel.add(slider);
      slider.setPaintLabels(true);
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(5);
      slider.setMinorTickSpacing(1);

      slider.addChangeListener(new ChangeListener() {

         @Override
         public void stateChanged(ChangeEvent e) {
            setState(slider.getValue());
         }
      });
   } 

   public void addPropertyChangeListener(PropertyChangeListener listener) {
      mainPanel.addPropertyChangeListener(listener);
   }

   public Component getMainPanel() {
      return mainPanel;
   }

   public void setState(int state) {
      if (state > STATE_MAX || state < STATE_MIN) {
         throw new IllegalArgumentException("state: " + state);
      }
      int oldState = this.state;
      this.state = state;

      mainPanel.firePropertyChange(STATE, oldState, this.state);
   }

   public int getState() {
      return state;
   }

   public static void main(String[] args) {
      final ListenToSwing listenToSwing = new ListenToSwing();

      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            JFrame frame = new JFrame("ListenToSwing");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.getContentPane().add(listenToSwing.getMainPanel());
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
         }
      });

      listenToSwing.addPropertyChangeListener(new PropertyChangeListener() {

         @Override
         public void propertyChange(PropertyChangeEvent evt) {
            if (evt.getPropertyName().equals(ListenToSwing.STATE)) {
               System.out.println("New state: " + listenToSwing.getState());
            }
         }
      });
   }

}