Creating TextArea with Undo, Redo Capabilities

  
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;

class UndoableTextArea extends JTextArea implements UndoableEditListener, FocusListener,
    KeyListener {
  private UndoManager m_undoManager;

  public UndoableTextArea() {
    this(new String());
  }

  public UndoableTextArea(String text) {
    super(text);
    getDocument().addUndoableEditListener(this);
    this.addKeyListener(this);
    this.addFocusListener(this);
  }

  private void createUndoMananger() {
    m_undoManager = new UndoManager();
    m_undoManager.setLimit(10);
  }

  private void removeUndoMananger() {
    m_undoManager.end();
  }

  public void focusGained(FocusEvent fe) {
    createUndoMananger();
  }

  public void focusLost(FocusEvent fe) {
    removeUndoMananger();
  }

  public void undoableEditHappened(UndoableEditEvent e) {
    m_undoManager.addEdit(e.getEdit());
  }

  public void keyPressed(KeyEvent e) {
    if ((e.getKeyCode() == KeyEvent.VK_Z) && (e.isControlDown())) {
      try {
        m_undoManager.undo();
      } catch (CannotUndoException cue) {
        Toolkit.getDefaultToolkit().beep();
      }
    }

    if ((e.getKeyCode() == KeyEvent.VK_Y) && (e.isControlDown())) {
      try {
        m_undoManager.redo();
      } catch (CannotRedoException cue) {
        Toolkit.getDefaultToolkit().beep();
      }
    }
  }

  public void keyReleased(KeyEvent e) {
  }

  public void keyTyped(KeyEvent e) {
  }
}

public class Main extends JFrame {
  UndoableTextArea m_undoableTextArea = new UndoableTextArea();

  public Main() {
    JScrollPane sc = new JScrollPane(m_undoableTextArea);
    getContentPane().setLayout(new BorderLayout(10, 10));
    getContentPane()
        .add(BorderLayout.NORTH, new JLabel("Press, CTRL+Z to Undo, CTRL+Y to Redo..."));
    getContentPane().add(BorderLayout.CENTER, sc);
  }

  public static void main(String[] arg) {
    Main m = new Main();
    m.setVisible(true);
    m.setSize(new Dimension(400, 300));
    m.validate();
  }
}

1.	The use of UndoableToggleEdit
2.	The use of StateEdit(able)
3.	The use of UndoManager
4.	A sample app showing the use of UndoableToggleEdit and CompoundEdit
5.	An example that shows lots of little UndoManager details
6.	Undo redo textarea
7.	Undo manager
8.	Simple GUI demo of UndoManager and friends
9.	Undo Example 1
10.	Undo Example 2
11.	Undo Example 3
12.	Undo Example 4
13.	Undo Example 5
14.	Undo Example 6
15.	Undoable Drawing Panel 2
16.	Undo Drawing
17.	Undo Example 7
18.	Add Undo and Redo to a text component
19.	Add undo support to the StyleFrame example
20.	Adding Undo and Redo to a Text Component
21.	Create a redo action and add it to the text component (JTextComponent)
22.	Listen for undo and redo events
23.	Create an undo action and add it to the text component
24.	Bind the undo action to ctl-Z

Creating TextArea with Undo, Redo Capabilities : Undo Redo « Swing JFC « Java

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