Help with passing events between components.

[Chris Waguespack]

I have a JFrame, and when a button is clicked, it needs to pop up a custom JDialog. In this JDialog, a user inputs data and clicks ok to pass the data back to the JFrame, so it can be saved off. I can do this using Flex/Actionscript 3.0, but can't figure out how to get it working in Java. Below are code fragments from AS3.0.

// Code in Actionscript 3.0
 
// MainFrame.as
public function addBtnClickHandler(e:Event):void {
var popup:AddItemPopup = new AddItemPopup();
popup.addEventListener(Event.EVENT_TYPE, handlerFunction);
PopUpManager.addPopUp(popup, this, true);
}
 
public function handlerFunction(e:Event):void {
// Do something.
}
 

// AddItemPopup.as
private function submit():void {
     newItem=new Item();
     newItem.number = numberInputTxt.text;
     dispatchEvent(new Event(Event.EVENT_TYPE, newItem, true));
     PopUpManager.removePopUp(this);
}

[Michael Dunn]

perhaps the simplest way is to set the dialog's modality to true, then when you
create the dialog you also call the method that will return the data. the data
will not be returned until the dialog disposes (or visible false).

simple demo
(click 'get name', enter something into the textfield, click 'ok'

    
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Testing
{
  JLabel lbl = new JLabel("Name = ");
  public void buildGUI()
  {
    JButton btn = new JButton("Get Name");
    final JFrame f = new JFrame();
    f.getContentPane().add(lbl,BorderLayout.NORTH);
    f.getContentPane().add(btn,BorderLayout.SOUTH);
    f.pack();
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        lbl.setText("Name = "+new MyDialog(f).getName());//<-----
      }
    });
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}
class MyDialog
{
  JDialog d;
  JTextField tf = new JTextField(10);
  public MyDialog(JFrame parent)
  {
    JButton btn = new JButton("OK");
    d = new JDialog(parent);
    d.getContentPane().add(tf,BorderLayout.NORTH);
    d.getContentPane().add(btn,BorderLayout.CENTER);
    d.setTitle("JDialog");
    d.setModal(true);//<--------------------
    d.pack();
    d.setLocation(parent.getX()+150,parent.getY());
    d.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        d.dispose();
      }
    });
    d.setVisible(true);
  }
  public String getName(){return tf.getText();}//<-----
}

[Chris Waguespack]

Thank you, but I don't believe this will work (because there will be a cancel button that calls dispose(); ). Is there any good way to do this using events and listeners?

Thank you,
Chris

[Michael Dunn]

another way

    
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Testing
{
  private JLabel lbl = new JLabel("Name = ");
  public void buildGUI()
  {
    JButton btn = new JButton("Get Name");
    final JFrame f = new JFrame();
    f.getContentPane().add(lbl,BorderLayout.NORTH);
    f.getContentPane().add(btn,BorderLayout.SOUTH);
    f.pack();
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        new MyDialog(Testing.this,f);
      }
    });
  }
  public JLabel getLabel()
  {
    return lbl;
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}
class MyDialog
{
  JDialog d;
  JTextField tf = new JTextField(10);
  Testing mainApp;
  public MyDialog(Testing t,JFrame parent)
  {
    mainApp = t;
    JButton btn = new JButton("OK");
    d = new JDialog(parent);
    d.getContentPane().add(tf,BorderLayout.NORTH);
    d.getContentPane().add(btn,BorderLayout.CENTER);
    d.setTitle("JDialog");
    d.setModal(true);
    d.pack();
    d.setLocation(parent.getX()+150,parent.getY());
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        mainApp.getLabel().setText("Name = "+tf.getText());
      }
    });
    d.setVisible(true);
  }
}

[Chris Waguespack]

Hmm, I think this would work, but I would like to have the dialog window not care what called it. I've been looking into using addActionListener() and dispatchEvent() and have tried created my own custom event/listener but can't seem to figure out exactly what to do. Any suggestions?

Thank you,
Chris

[Michael Dunn]

> but I would like to have the dialog window not care what called it.

that's the first example I posted

[Chris Waguespack]

> that's the first example I posted

The text would be set to the value of the input every time, and I need it to be able to not do anything if the user clicks a 'Cancel' button. I would also prefer this to be done using listeners, as I need it as reusable as possible.

Thank you,
Chris

P.S. Thanks for the help so far.

[Michael Dunn]

here's the first example modified for cancel/ok (with empty textfield)/ok

    
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Testing
{
  JLabel lbl = new JLabel("Name = ");
  public void buildGUI()
  {
    JButton btn = new JButton("Get Name");
    final JFrame f = new JFrame();
    f.getContentPane().add(lbl,BorderLayout.NORTH);
    f.getContentPane().add(btn,BorderLayout.SOUTH);
    f.pack();
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        String retVal = new MyDialog(f).getName();
        String temp = "";
        if(retVal == null) temp = "Cancelled";
        else if(retVal.equals("")) temp = "nothing entered";
        else temp = "Name = "+retVal;
        lbl.setText(temp);
      }
    });
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}
class MyDialog
{
  JDialog d;
  String returnValue = null;
  public MyDialog(JFrame parent)
  {
    JPanel p = new JPanel(new GridLayout(1,2));
    JButton cancelBtn = new JButton("Cancel");
    JButton okBtn = new JButton("OK");
    p.add(cancelBtn); p.add(okBtn);
    final JTextField tf = new JTextField(10);
    d = new JDialog(parent);
    d.getContentPane().add(tf,BorderLayout.NORTH);
    d.getContentPane().add(p,BorderLayout.CENTER);
    d.setTitle("JDialog");
    d.setModal(true);
    d.pack();
    d.setLocation(parent.getX()+150,parent.getY());
    d.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
    okBtn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        returnValue = tf.getText();
        d.dispose();
      }
    });
    cancelBtn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        d.dispose();
      }
    });
    d.setVisible(true);
  }
  public String getName(){return returnValue;}
}

I don't fully understand the requirements - perhaps all you need is a
JOptionPane.showInputDialog(...)

[Chris Waguespack]

Thanks for the help. I finally decided to go with an MVC approach and that seems to be working like I need it to.