Static Input Dialog with JDialog

Question

I made this sample:

import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class JDialogTest extends JDialog implements ActionListener{
    private boolean actionPerformed;
    private JButton okButton;
    private JTextField textField;

    private JDialogTest(String title, JFrame frame){
        super(frame, title, true);
        setDefaultCloseOperation(HIDE_ON_CLOSE);
        setMinimumSize(new Dimension(200, 200));
        init();
    }

    public static String getInput(String title, JFrame frame){
        JDialogTest input = new JDialogTest(title, frame);
        input.setVisible(true);

        while(true){
            if(input.actionPerformed){
                input.setVisible(false);
                String text = input.textField.getText();
                return text;
            }
        }
    }

    private void init(){

        textField = new JTextField();
        okButton = new JButton("OK");
        okButton.addActionListener(this);

        setLayout(new GridLayout(2, 1, 5, 5));

        add(textField);
        add(okButton);
        pack();     
    }

    @Override
    public void actionPerformed(ActionEvent evt) {
        System.out.println("click");
        actionPerformed = true;     
    }

    public static void main(String[] args) {
        System.out.println(JDialogTest.getInput("Test", null));
    }



}

I create new Dialog via a static method witch returns a string. But the while-loop witch should detect if the button was pressed won't get started! I know about JOptionPanes but I don't want to use them. I tried using a JFrame instead but it doesn't work if I try to init the Dialog inside of another JFrame/JDialog (it doesn't render).

Answer 1

With while(true) running in the same thread as the gui, is gonna to freeze your view, and is not the proper way you are using listeners. As your dialog is modal then the dialog has the flowcontrol.

Look at this SSCCE based in your example , with a few changes.

Example:

public class JDialogTest {

    private JDialog dialog;
    private JTextField textField;

private JDialogTest (String title, JFrame frame){
    dialog = new JDialog(frame, title, true);
    dialog.setDefaultCloseOperation(JDialog.HIDE_ON_CLOSE);
    dialog.setMinimumSize(new Dimension(200, 200));
    init();
}

public void setVisible(Boolean flag){
    dialog.setVisible(flag);
}

public static String getInput(String title, JFrame frame){
    JDialogTest input = new JDialogTest (title, frame);
    input.setVisible(true);
    String text = input.textField.getText();
    return text;
}

private void init(){

    textField = new JTextField();
    JButton okButton = new JButton("OK");
    okButton.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                dialog.dispose();
            }

    });

    dialog.setLayout(new GridLayout(2, 1, 5, 5));

    dialog.add(textField);
    dialog.add(okButton);
    dialog.pack();     
}

public static void main(String args []){
    String s = getInput("Dialog",null);
    System.out.println(s);
}


}

Answer 2

Again you wan to use a a modal JDialog and then query it for the text it holds once it has been dealt with. Since the dialog is modal, your calling application will know when the button has been pressed, if you make the dialog invisible within the button's ActionListener. This will then return control to the calling program. Your calling program can then query the dialog by calling a public method that you give it (here I called it getText() then then returns the String held by the dialog's JTextField.

For example, using your code...

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

public class JDialogTest extends JDialog implements ActionListener {
   // private boolean actionPerformed;
   private JButton okButton;
   private JTextField textField;

   private JDialogTest(String title, JFrame frame) {
      super(frame, title, true);
      setDefaultCloseOperation(HIDE_ON_CLOSE);
      setMinimumSize(new Dimension(200, 200));
      init();
   }

   // public static String getInput(String title, JFrame frame) {
   // JDialogTest input = new JDialogTest(title, frame);
   // input.setVisible(true);
   //
   // while (true) {
   // if (input.actionPerformed) {
   // input.setVisible(false);
   // String text = input.textField.getText();
   // return text;
   // }
   // }
   // }

   private void init() {

      textField = new JTextField();
      okButton = new JButton("OK");
      okButton.addActionListener(this);

      // UGLY layout
      setLayout(new GridLayout(2, 1, 5, 5));

      add(textField);
      add(okButton);
      pack();
   }

   // I've added this method to allow outside methods to get text
   public String getText() {
      return textField.getText();
   }

   @Override
   public void actionPerformed(ActionEvent evt) {
      System.out.println("click");
      // actionPerformed = true;
      setVisible(false);
   }

   private static void createAndShowGui() {
      final JTextField textField = new JTextField(20);
      JFrame frame = new JFrame("Test JFrame");
      final JDialogTest jDialogTest = new JDialogTest("Dialog", frame);

      JButton button = new JButton(
            new AbstractAction("Press Me to Show Dialog") {
               @Override
               public void actionPerformed(ActionEvent arg0) {
                  jDialogTest.setVisible(true);  // code is frozen here
                                          // until the dialog is no longer visible


                  // when code flow reaches here, we know that the dialog
                  // is no longer visible and 
                  // we now can query our JDialog to get its text
                  textField.setText(jDialogTest.getText());
               }
            });

      textField.setFocusable(false);
      JPanel panel = new JPanel();
      panel.add(button);
      panel.add(textField);

      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(panel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

---

Edit

If you want to display the dialog in a static way, change your getInput method to simply:

public static String getInput(String title, JFrame frame) {
  JDialogTest input = new JDialogTest(title, frame);

  input.setVisible(true);

  return input.getText();
}

---

Changes to calling code:

  final JTextField textField = new JTextField(20);
  final JFrame frame = new JFrame("Test JFrame");

  JButton button = new JButton(
        new AbstractAction("Press Me to Show Dialog") {
           @Override
           public void actionPerformed(ActionEvent arg0) {                  
              String result = JDialogTest.getInput("Get Input", frame);
              textField.setText(result);
           }
        });

---

Edit 2

Note that JOptionPane works great:

String result = JOptionPane.showInputDialog(frame, "Please enter input:", 
      "Get Input", JOptionPane.PLAIN_MESSAGE);

---

Edit 3
You ask:

The solution in the edit seems to work but what method should I use in the action listener to close the JDialog and return the text?

The dialog button's ActionListener will make the dialog invisible by either calling setVisible(false) or dispose(). See my code above or nachokk's code for examples.

Answer 3

Here is one possible solution. Take special note of the changes to the JDialogTest constructor, getInput() and actionPerformed().

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

public class JDialogTest extends JDialog implements ActionListener{
    private JButton okButton;
    private JTextField textField;

    private JDialogTest(String title, JFrame frame){
        super(frame, title, true);
        this.setModal(true);                   // Set the dialog as modal
        setDefaultCloseOperation(HIDE_ON_CLOSE);
        setMinimumSize(new Dimension(200, 200));
        init();
    }

    public static String getInput(String title, JFrame frame){
        JDialogTest input = new JDialogTest(title, frame);
        input.setVisible(true);
        return input.textField.getText();       // If this is executed, the dialog box has closed
    }

    private void init(){

        textField = new JTextField();
        okButton = new JButton("OK");
        okButton.addActionListener(this);

        setLayout(new GridLayout(2, 1, 5, 5));

        add(textField);
        add(okButton);
        pack();     
    }

    @Override
    public void actionPerformed(ActionEvent evt) {
        System.out.println("click");
        setVisible(false);             // Close the modal dialog box  
    }

    public static void main(String[] args) {
        System.out.println(JDialogTest.getInput("Test", null));
    }
}