Keybindings for undo/redo buttons.

Question

I thought I knew how to do this, and I do seem to have this working fine for cut/copy/paste/select all keybindings CTRL X/C/V/A respectively.
However I tried to do this for CTRL X and Y undo/redo and it's not working as I intended. Can anyone see what I'm doing wrong?
I created a SSCCE based off the original example I was following from: [http://www.java2s.com/Code/Java/Swing-JFC/Undoredotextarea.htm]
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.UndoManager;
public class UndoRedoTextArea extends JFrame implements KeyListener{
    private static final long serialVersionUID = 1L;
    protected JTextArea textArea = new JTextArea();
    protected UndoManager undoManager = new UndoManager();
    protected JButton undoButton = new JButton("Undo");
    protected JButton redoButton = new JButton("Redo");
    public UndoRedoTextArea() {
        super("Undo/Redo Demo");
        undoButton.setEnabled(false);
        redoButton.setEnabled(false);
        JPanel buttonPanel = new JPanel(new GridLayout());
        buttonPanel.add(undoButton);
        buttonPanel.add(redoButton);
        JScrollPane scroller = new JScrollPane(textArea);
        getContentPane().add(buttonPanel, BorderLayout.NORTH);
        getContentPane().add(scroller, BorderLayout.CENTER);
        textArea.getDocument().addUndoableEditListener(
            new UndoableEditListener() {
                public void undoableEditHappened(UndoableEditEvent e) {
                    undoManager.addEdit(e.getEdit());
                    updateButtons();
        undoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                try {
                    undoManager.undo();
                } catch (CannotRedoException cre) {
                    cre.printStackTrace();
                updateButtons();
        undoButton.addKeyListener(this);
        redoButton.addKeyListener(this);
        redoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                try {
                    undoManager.redo();
                } catch (CannotRedoException cre)  {
                    cre.printStackTrace();
                updateButtons();
        setSize(400, 300);
        setVisible(true);
    public void updateButtons() {
        undoButton.setText(undoManager.getUndoPresentationName());
        redoButton.setText(undoManager.getRedoPresentationName());
        undoButton.setEnabled(undoManager.canUndo());
        redoButton.setEnabled(undoManager.canRedo());
    public static void main(String argv[]) {
        new UndoRedoTextArea();
    public void keyPressed(KeyEvent e){
        if (e.equals(KeyStroke.getKeyStroke
            (KeyEvent.VK_Z, InputEvent.CTRL_DOWN_MASK))){
            // undo
            try {
                undoManager.undo();
            } catch (CannotRedoException cre)  {
                cre.printStackTrace();
            updateButtons();
        else if (e.equals(KeyStroke.getKeyStroke
                (KeyEvent.VK_Y, InputEvent.CTRL_DOWN_MASK))){
            // redo
            try  {
                undoManager.redo();
            } catch (CannotRedoException cre) {
                cre.printStackTrace();
            updateButtons();
    public void keyTyped(KeyEvent e){}
    public void keyReleased(KeyEvent e){}
}Edited by: G-Unit on Oct 24, 2010 5:30 AM

Answer 1

camickr wrote:
So the way I posted in the second lump of code OK (3rd post) or did you mean something different? Why did you set the key bindings? Did I not state they would be created automatically? I think you need to reread my suggestion (and the tutorial).Because I don't get it, it says only Menu items can contain accelerators and buttons only get mnemonics. I'm not using menu items here, I only have a text pane and 2 buttons. So I set the actions for the InputMap in TextPane. For the buttons, I pretty much used the small bit of code using undoManager.
I tried to set KEYSTROKE constructor for the action and simply add them to the buttons that way, but this didn't seem to have any response.
Also I don't get how this could happen anyway if the TextPane has the focus.
Not like the example using MNEMONICS.
    Action leftAction = new LeftAction(); //LeftAction code is shown later
    button = new JButton(leftAction)
    menuItem = new JMenuItem(leftAction);
To create an Action object, you generally create a subclass of AbstractAction and then instantiate it. In your subclass, you must implement the actionPerformed method to react appropriately when the action event occurs. Here's an example of creating and instantiating an AbstractAction subclass:
    leftAction = new LeftAction("Go left", anIcon,
                 "This is the left button.",
                 new Integer(KeyEvent.VK_L));
    class LeftAction extends AbstractAction {
        public LeftAction(String text, ImageIcon icon,
                          String desc, Integer mnemonic) {
            super(text, icon);
            putValue(SHORT_DESCRIPTION, desc);
            putValue(MNEMONIC_KEY, mnemonic);
        public void actionPerformed(ActionEvent e) {
            displayResult("Action for first button/menu item", e);
    }This is what I attempted. No errors... It just doesn't work.
public JPanel p()
    undoButton.addActionListener(new UndoAction(KeyStroke.getKeyStroke(KeyEvent.VK_Z, Event.CTRL_MASK)));
    panel.add(undoButton);
    return panel;
private class UndoAction extends AbstractAction
     public UndoAction(KeyStroke keyStroke)
          putValue(ACCELERATOR_KEY, keyStroke);
     private static final long serialVersionUID = 1L;
     public void actionPerformed(ActionEvent e)
          try
               if (undoManager.canUndo())
                    undoManager.undo();
          catch (CannotRedoException cre)
               cre.printStackTrace();
          updateButtons();
}Edited by: G-Unit on Oct 25, 2010 8:32 AM