Java/Swing JFC/Undo Redo

Содержание

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

Adding Undo and Redo to a Text Component

   <source lang="java">

import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.JFrame; 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.text.Document; import javax.swing.text.JTextComponent; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class Main{ public static void main(String[] argv) throws Exception{

   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   JFrame f = new JFrame();
   f.add(new JScrollPane(textcomp));
   f.setSize(330,300);
   f.setVisible(true);
   
   doc.addUndoableEditListener(new UndoableEditListener() {
       public void undoableEditHappened(UndoableEditEvent evt) {
           undo.addEdit(evt.getEdit());
       }
   });
   
   textcomp.getActionMap().put("Undo",
       new AbstractAction("Undo") {
           public void actionPerformed(ActionEvent evt) {
               try {
                   if (undo.canUndo()) {
                       undo.undo();
                   }
               } catch (CannotUndoException e) {
               }
           }
      });
   
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
   
   textcomp.getActionMap().put("Redo",
       new AbstractAction("Redo") {
           public void actionPerformed(ActionEvent evt) {
               try {
                   if (undo.canRedo()) {
                       undo.redo();
                   }
               } catch (CannotRedoException e) {
               }
           }
       });
   
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");

}}

 </source>

Add Undo and Redo to a text component

   <source lang="java">

import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.JTextArea; import javax.swing.KeyStroke; import javax.swing.event.UndoableEditEvent; import javax.swing.event.UndoableEditListener; import javax.swing.text.Document; import javax.swing.text.JTextComponent; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class Main {

 public static void main(String[] argv) throws Exception {
   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   doc.addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       undo.addEdit(evt.getEdit());
     }
   });
   textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canUndo()) {
           undo.undo();
         }
       } catch (CannotUndoException e) {
       }
     }
   });
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
   textcomp.getActionMap().put("Redo", new AbstractAction("Redo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canRedo()) {
           undo.redo();
         }
       } catch (CannotRedoException e) {
       }
     }
   });
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");
 }

}

 </source>

Add undo support to the StyleFrame example

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoStyleFrame.java //Add undo support to the StyleFrame example. This example only //retains the most recent edit, to keep things simple. import java.awt.BorderLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.AbstractAction; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextField; import javax.swing.JTextPane; import javax.swing.SwingConstants; import javax.swing.event.UndoableEditEvent; import javax.swing.event.UndoableEditListener; import javax.swing.text.Style; import javax.swing.text.StyleConstants; import javax.swing.text.StyleContext; import javax.swing.undo.UndoableEdit; public class UndoStyleFrame extends StyleFrame {

 protected UndoAct undoAction = new UndoAct(); // an Action for undo
 protected RedoAct redoAction = new RedoAct(); // an Action for redo
 public UndoStyleFrame() {
   super();
   setTitle("UndoStyleFrame");
   // register the Actions as undo listeners (we inherited textPane)
   textPane.getDocument().addUndoableEditListener(undoAction);
   textPane.getDocument().addUndoableEditListener(redoAction);
   // create menu for undo/redo
   JMenu editMenu = new JMenu("Edit");
   editMenu.add(new JMenuItem(undoAction));
   editMenu.add(new JMenuItem(redoAction));
   menuBar.add(editMenu); // we inherited menuBar from superclass
   // create buttons for undo/redo
   JPanel buttonPanel = new JPanel();
   buttonPanel.add(new JButton(undoAction));
   buttonPanel.add(new JButton(redoAction));
   getContentPane().add(buttonPanel, java.awt.BorderLayout.SOUTH);
 }
 // begin inner classes ------------
 public class UndoAct extends AbstractAction implements UndoableEditListener {
   private UndoableEdit edit;
   public UndoAct() {
     super("Undo");
     setEnabled(false);
   }
   public void updateEnabled() {
     setEnabled(edit.canUndo());
   }
   public void undoableEditHappened(UndoableEditEvent event) {
     edit = event.getEdit();
     putValue(NAME, edit.getUndoPresentationName());
     updateEnabled();
   }
   public void actionPerformed(ActionEvent ae) {
     edit.undo();
     updateEnabled(); // disable undo
     redoAction.updateEnabled(); // enable redo
   }
 }
 public class RedoAct extends AbstractAction implements UndoableEditListener {
   private UndoableEdit edit;
   public RedoAct() {
     super("Redo");
     setEnabled(false);
   }
   public void updateEnabled() {
     setEnabled(edit.canRedo());
   }
   public void undoableEditHappened(UndoableEditEvent event) {
     edit = event.getEdit();
     putValue(NAME, edit.getRedoPresentationName());
     updateEnabled();
   }
   public void actionPerformed(ActionEvent ae) {
     edit.redo();
     updateEnabled(); // disable redo
     undoAction.updateEnabled(); // enable undo
   }
 }
 // end inner classes ------------
 public static void main(String[] args) {
   JFrame frame = new UndoStyleFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.setSize(400, 300);
   frame.setVisible(true);
 }

} //StyleFrame.java //A JTextPane with a menu for Style manipulation. class StyleFrame extends JFrame implements ActionListener {

 protected StyleBox styleBox;
 protected JTextPane textPane;
 protected JMenuBar menuBar;
 protected JMenu applyStyleMenu, modifyStyleMenu;
 protected JMenuItem createItem;
 public StyleFrame() {
   super("StyleFrame");
   styleBox = new StyleBox();
   textPane = new JTextPane();
   getContentPane().add(new JScrollPane(textPane), BorderLayout.CENTER);
   // set up menu
   menuBar = new JMenuBar();
   JMenu styleMenu = new JMenu("Style");
   menuBar.add(styleMenu);
   setJMenuBar(menuBar);
   applyStyleMenu = new JMenu("Set Logical Style");
   applyStyleMenu
       .setToolTipText("set the Logical Style for the paragraph at caret location");
   styleMenu.add(applyStyleMenu);
   modifyStyleMenu = new JMenu("Modify Style");
   modifyStyleMenu
       .setToolTipText("redefine a named Style (will affect paragraphs using that style)");
   styleMenu.add(modifyStyleMenu);
   createItem = new JMenuItem("Create New Style");
   createItem
       .setToolTipText("define a new Style (which can then be applied to paragraphs)");
   createItem.addActionListener(this);
   styleMenu.add(createItem);
   // add the default style to applyStyleMenu and modifyStyleMenu
   createMenuItems(StyleContext.DEFAULT_STYLE);
 }
 protected void createMenuItems(String styleName) {
   // add "styleName" to applyStyleMenu and modifyStyleMenu
   JMenuItem applyItem = new JMenuItem(styleName);
   applyItem.addActionListener(this);
   applyStyleMenu.add(applyItem);
   JMenuItem modifyItem = new JMenuItem(styleName);
   modifyItem.addActionListener(this);
   modifyStyleMenu.add(modifyItem);
 }
 public void actionPerformed(ActionEvent e) {
   // determine which menuItem was invoked and process it
   JMenuItem source = (JMenuItem) e.getSource();
   if (applyStyleMenu.isMenuComponent(source)) {
     // apply an existing style to the paragraph at the caret position
     String styleName = source.getActionCommand();
     Style style = textPane.getStyle(styleName);
     textPane.setLogicalStyle(style);
   }
   if (source == createItem) {
     // define a new Style and add it to the menus
     styleBox.clear();
     int response = JOptionPane.showConfirmDialog(this, styleBox,
         "Style Editor", JOptionPane.OK_CANCEL_OPTION,
         JOptionPane.PLAIN_MESSAGE);
     if (response == JOptionPane.OK_OPTION
         && styleBox.getStyleName().length() > 0) {
       String styleName = styleBox.getStyleName();
       Style style = textPane.addStyle(styleName, null);
       styleBox.fillStyle(style);
       createMenuItems(styleName); // add new Style to the menus
     }
   }
   if (modifyStyleMenu.isMenuComponent(source)) {
     // redefine a Style (will automatically redraw paragraphs using
     // Style)
     String styleName = source.getActionCommand();
     Style style = textPane.getStyle(styleName);
     styleBox.loadFromStyle(style);
     int response = JOptionPane.showConfirmDialog(this, styleBox,
         "Style Editor", JOptionPane.OK_CANCEL_OPTION,
         JOptionPane.PLAIN_MESSAGE);
     if (response == JOptionPane.OK_OPTION)
       styleBox.fillStyle(style);
   }
 }
 public static void main(String[] args) {
   JFrame frame = new StyleFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.setSize(400, 300);
   frame.setVisible(true);
 }

} //StyleBox.java //A control panel that can be used to edit a style"s paragraph attributes. class StyleBox extends JPanel {

 private static final String[] fonts = { "Monospaced", "Serif", "SansSerif" };
 private static final String[] sizes = { "8", "10", "12", "18", "24", "36" };
 private JTextField nameField;
 private JComboBox fontCombo, sizeCombo;
 private JTextField leftField, rightField, aboveField, belowField;
 private JCheckBox boldCheck, italicCheck;
 public StyleBox() {
   // create the fields and lay them out
   super(new BorderLayout(4, 4));
   JPanel labelPanel = new JPanel(new GridLayout(8, 1, 0, 2));
   JPanel valuePanel = new JPanel(new GridLayout(8, 1, 0, 2));
   add(labelPanel, BorderLayout.WEST);
   add(valuePanel, BorderLayout.CENTER);
   JLabel lab;
   JPanel sidePanel;
   lab = new JLabel("Style Name", SwingConstants.RIGHT);
   labelPanel.add(lab);
   nameField = new JTextField();
   lab.setLabelFor(nameField);
   valuePanel.add(nameField);
   lab = new JLabel("Font", SwingConstants.RIGHT);
   labelPanel.add(lab);
   fontCombo = new JComboBox(fonts);
   fontCombo.setEditable(true); // user may enter custom value
   lab.setLabelFor(fontCombo);
   valuePanel.add(fontCombo);
   lab = new JLabel("Size", SwingConstants.RIGHT);
   labelPanel.add(lab);
   sizeCombo = new JComboBox(sizes);
   sizeCombo.setEditable(true); // user may enter custom value
   lab.setLabelFor(sizeCombo);
   sidePanel = new JPanel(new BorderLayout(4, 0));
   sidePanel.add(sizeCombo, BorderLayout.CENTER);
   sidePanel.add(new JLabel("points"), BorderLayout.EAST);
   valuePanel.add(sidePanel);
   lab = new JLabel("Left Indent", SwingConstants.RIGHT);
   labelPanel.add(lab);
   leftField = new JTextField();
   lab.setLabelFor(leftField);
   sidePanel = new JPanel(new BorderLayout(4, 0));
   sidePanel.add(leftField, BorderLayout.CENTER);
   sidePanel.add(new JLabel("points"), BorderLayout.EAST);
   valuePanel.add(sidePanel);
   lab = new JLabel("Right Indent", SwingConstants.RIGHT);
   labelPanel.add(lab);
   rightField = new JTextField();
   lab.setLabelFor(rightField);
   sidePanel = new JPanel(new BorderLayout(4, 0));
   sidePanel.add(rightField, BorderLayout.CENTER);
   sidePanel.add(new JLabel("points"), BorderLayout.EAST);
   valuePanel.add(sidePanel);
   lab = new JLabel("Space Above", SwingConstants.RIGHT);
   labelPanel.add(lab);
   aboveField = new JTextField();
   lab.setLabelFor(aboveField);
   sidePanel = new JPanel(new BorderLayout(4, 0));
   sidePanel.add(aboveField, BorderLayout.CENTER);
   sidePanel.add(new JLabel("points"), BorderLayout.EAST);
   valuePanel.add(sidePanel);
   lab = new JLabel("Space Below", SwingConstants.RIGHT);
   labelPanel.add(lab);
   belowField = new JTextField();
   lab.setLabelFor(belowField);
   sidePanel = new JPanel(new BorderLayout(4, 0));
   sidePanel.add(belowField, BorderLayout.CENTER);
   sidePanel.add(new JLabel("points"), BorderLayout.EAST);
   valuePanel.add(sidePanel);
   boldCheck = new JCheckBox("Bold");
   italicCheck = new JCheckBox("Italic");
   sidePanel = new JPanel(new GridLayout(1, 2));
   sidePanel.add(boldCheck);
   sidePanel.add(italicCheck);
   valuePanel.add(sidePanel);
   clear(); // sets initial values, etc.
 }
 public void clear() {
   // reset all fields (also sets nameField to be editable)
   nameField.setText("");
   nameField.setEditable(true);
   fontCombo.setSelectedIndex(0);
   sizeCombo.setSelectedIndex(2);
   leftField.setText("0.0");
   rightField.setText("0.0");
   aboveField.setText("0.0");
   belowField.setText("0.0");
   boldCheck.setSelected(false);
   italicCheck.setSelected(false);
 }
 public String getStyleName() {
   // return the name of the style
   String name = nameField.getText();
   if (name.length() > 0)
     return name;
   else
     return null;
 }
 public void fillStyle(Style style) {
   // mutate "style" with the values entered in the fields
   // (no value checking--could throw NumberFormatException)
   String font = (String) fontCombo.getSelectedItem();
   StyleConstants.setFontFamily(style, font);
   String size = (String) sizeCombo.getSelectedItem();
   StyleConstants.setFontSize(style, Integer.parseInt(size));
   String left = leftField.getText();
   StyleConstants.setLeftIndent(style, Float.valueOf(left).floatValue());
   String right = rightField.getText();
   StyleConstants.setRightIndent(style, Float.valueOf(right).floatValue());
   String above = aboveField.getText();
   StyleConstants.setSpaceAbove(style, Float.valueOf(above).floatValue());
   String below = belowField.getText();
   StyleConstants.setSpaceBelow(style, Float.valueOf(below).floatValue());
   boolean bold = boldCheck.isSelected();
   StyleConstants.setBold(style, bold);
   boolean italic = italicCheck.isSelected();
   StyleConstants.setItalic(style, italic);
 }
 // Load the form from an existing Style.
 public void loadFromStyle(Style style) {
   nameField.setText(style.getName());
   nameField.setEditable(false); // don"t allow name change
   String fam = StyleConstants.getFontFamily(style);
   fontCombo.setSelectedItem(fam);
   int size = StyleConstants.getFontSize(style);
   sizeCombo.setSelectedItem(Integer.toString(size));
   float left = StyleConstants.getLeftIndent(style);
   leftField.setText(Float.toString(left));
   float right = StyleConstants.getRightIndent(style);
   rightField.setText(Float.toString(right));
   float above = StyleConstants.getSpaceAbove(style);
   aboveField.setText(Float.toString(above));
   float below = StyleConstants.getSpaceBelow(style);
   belowField.setText(Float.toString(below));
   boolean bold = StyleConstants.isBold(style);
   boldCheck.setSelected(bold);
   boolean italic = StyleConstants.isItalic(style);
   italicCheck.setSelected(italic);
 }

}

 </source>

An example that shows lots of little UndoManager details

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoManagerDetails.java //An example that shows lots of little UndoManager details // import java.util.Enumeration; import java.util.Vector; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; import javax.swing.undo.UndoableEdit; public class UndoManagerDetails {

 public static void main(String[] args) {
   UndoManager mgr = new UndoManager();
   // Show how insignificant edits are skipped over.
   //
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(1, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(2, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(3, false, false, false));
   mgr.addEdit(new SampleUndoableEdit(4, false, false, false));
   System.out.println("--------------------------");
   System.out.println("Insignificant edit example");
   System.out.println("--------------------------");
   mgr.undo();
   mgr.redo();
   System.out.println(mgr.canRedo()); // No more sig. edits
   // Show how edits that call add/replace are used.
   //
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(5, true, true, false));
   mgr.addEdit(new SampleUndoableEdit(6, false, true, false));
   System.out.println("----------------------------------");
   System.out.println("Absorbed (by addEdit) edit example");
   System.out.println("----------------------------------");
   mgr.undo();
   mgr.discardAllEdits();
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(1, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(2, false, true, true));
   System.out.println("--------------------------------------");
   System.out.println("Absorbed (by replaceEdit) edit example");
   System.out.println("--------------------------------------");
   mgr.undo();
   System.out.println(mgr.canUndo());
   // Show how changing limit works.
   mgr.discardAllEdits();
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(1, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(2, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(3, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(4, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(5, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(6, false, true, false));
   System.out.println("----------------------");
   System.out.println("Changing limit example");
   System.out.println("----------------------");
   mgr.undo();
   mgr.undo();
   mgr.undo(); // Now 3 undoable, 3 redoable
   mgr.setLimit(4); // Now 2 undoable, 2 redoable!
   while (mgr.canUndo())
     mgr.undo();
   while (mgr.canRedo())
     mgr.redo();
   // undoOrRedo example
   mgr.discardAllEdits();
   mgr.setLimit(1);
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(1, false, true, false));
   System.out.println("------------------");
   System.out.println("undoOrRedo example");
   System.out.println("------------------");
   System.out.println(mgr.getUndoOrRedoPresentationName());
   mgr.undoOrRedo();
   System.out.println(mgr.getUndoOrRedoPresentationName());
   mgr.undoOrRedo();
   // Show how UndoManager becomes a CompositeEdit.
   mgr.discardAllEdits();
   mgr.setLimit(100);
   //                                 # adds? sig? replace?
   mgr.addEdit(new SampleUndoableEdit(1, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(2, false, true, false));
   mgr.addEdit(new SampleUndoableEdit(3, false, true, false));
   System.out.println("------------------------------");
   System.out.println("Transform to composite example");
   System.out.println("------------------------------");
   mgr.end();
   mgr.undo();
   mgr.redo();
   // Show that adds are no longer allowed. Note that addEdit() returns
   // true in
   // pre-JDK 1.2 Swing releases. This is fixed in JDK 1.2.
   System.out.println(mgr.addEdit(new SampleUndoableEdit(4, false, true,
       false)));
   mgr.undo(); // note that edit 4 is not there
 }

} //SampleUndoableEdit.java //A simple (?) example of an undoable edit. // class SampleUndoableEdit extends AbstractUndoableEdit {

 private boolean isSignificant;
 private boolean isReplacer;
 private int number;
 private boolean allowAdds;
 private Vector addedEdits;
 private UndoableEdit replaced;
 // Create a new edit with an identifying number. The boolean arguments
 // define
 // the edit"s behavior.
 public SampleUndoableEdit(int number, boolean allowAdds,
     boolean isSignificant, boolean isReplacer) {
   this.number = number;
   this.allowAdds = allowAdds;
   if (allowAdds)
     addedEdits = new Vector();
   this.isSignificant = isSignificant;
   this.isReplacer = isReplacer;
 }
 // "Undo" the edit by printing a message to the screen.
 public void undo() throws CannotUndoException {
   super.undo();
   System.out.print("Undo " + number);
   dumpState();
 }
 // "Redo" the edit by printing a message to the screen.
 public void redo() throws CannotRedoException {
   super.redo();
   System.out.print("Redo " + number);
   dumpState();
 }
 // If allowAdds is true, we store the input edit. If not, just return false.
 public boolean addEdit(UndoableEdit anEdit) {
   if (allowAdds) {
     addedEdits.addElement(anEdit);
     return true;
   } else
     return false;
 }
 // If isReplacer is true, we store the edit we are replacing.
 public boolean replaceEdit(UndoableEdit anEdit) {
   if (isReplacer) {
     replaced = anEdit;
     return true;
   } else
     return false;
 }
 // Significance is based on constructor parameter.
 public boolean isSignificant() {
   return isSignificant;
 }
 // Just return our identifier.
 public String toString() {
   return "<" + number + ">";
 }
 // Debug output.
 public void dumpState() {
   if (allowAdds && addedEdits.size() > 0) {
     Enumeration e = addedEdits.elements();
     System.out.print(" (absorbed: ");
     while (e.hasMoreElements()) {
       System.out.print(e.nextElement());
     }
     System.out.print(")");
   }
   if (isReplacer && replaced != null) {
     System.out.print(" (replaced: " + replaced + ")");
   }
   System.out.println();
 }

}

 </source>

A sample app showing the use of UndoableToggleEdit and CompoundEdit

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoableToggleApp2.java //A sample app showing the use of UndoableToggleEdit and CompoundEdit. // import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JRadioButton; import javax.swing.JToggleButton; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.rupoundEdit; import javax.swing.undo.UndoableEdit; public class UndoableToggleApp2 extends JFrame {

 private CompoundEdit edit;
 private JButton undoButton;
 private JButton redoButton;
 private JButton endButton;
 // Create the main frame and everything in it.
 public UndoableToggleApp2() {
   // Create some toggle buttons (and subclasses)
   JToggleButton tog = new JToggleButton("ToggleButton");
   JCheckBox cb = new JCheckBox("CompoundEdit ExampleCheckBox");
   JRadioButton radio = new JRadioButton("RadioButton");
   // Add our listener to each toggle button
   SimpleListener sl = new SimpleListener();
   tog.addActionListener(sl);
   cb.addActionListener(sl);
   radio.addActionListener(sl);
   // Lay out the buttons
   Box buttonBox = new Box(BoxLayout.Y_AXIS);
   buttonBox.add(tog);
   buttonBox.add(cb);
   buttonBox.add(radio);
   // Create undo and redo buttons (initially disabled)
   undoButton = new JButton("Undo");
   redoButton = new JButton("Redo");
   endButton = new JButton("End");
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   endButton.setEnabled(false);
   // Add a listener to the undo button. It attempts to call undo() on the
   // current edit, then enables/disables the undo/redo buttons as
   // appropriate.
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.undo();
       } catch (CannotUndoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Add a redo listener: just like the undo listener, but for redo this
   // time.
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.redo();
       } catch (CannotRedoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Add an end listener. This listener will call end() on the
   // CompoundEdit
   // and update the undo/redo buttons.
   endButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       edit.end();
       endButton.setEnabled(false);
       undoButton.setEnabled(edit.canUndo());
       redoButton.setEnabled(edit.canRedo());
     }
   });
   // Layout the undo/redo/end buttons
   Box undoRedoEndBox = new Box(BoxLayout.X_AXIS);
   undoRedoEndBox.add(Box.createGlue());
   undoRedoEndBox.add(undoButton);
   undoRedoEndBox.add(Box.createHorizontalStrut(2));
   undoRedoEndBox.add(redoButton);
   undoRedoEndBox.add(Box.createHorizontalStrut(2));
   undoRedoEndBox.add(endButton);
   undoRedoEndBox.add(Box.createGlue());
   // Layout the main frame
   Container content = getContentPane();
   content.setLayout(new BorderLayout());
   content.add(buttonBox, BorderLayout.CENTER);
   content.add(undoRedoEndBox, BorderLayout.SOUTH);
   setSize(400, 150);
 }
 public class SimpleListener implements ActionListener {
   public void actionPerformed(ActionEvent ev) {
     if (edit == null || edit.isInProgress() == false)
       edit = new CompoundEdit();
     JToggleButton tb = (JToggleButton) ev.getSource();
     UndoableEdit togEdit = new UndoableToggleEdit(tb);
     edit.addEdit(togEdit);
     endButton.setEnabled(true);
     undoButton.setEnabled(edit.canUndo());
     redoButton.setEnabled(edit.canRedo());
   }
 }
 // Main program just creates the frame and displays it.
 public static void main(String[] args) {
   JFrame f = new UndoableToggleApp2();
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }

} //UndoableToggleEdit.java //An UndoableEdit used to undo the pressing of a JToggleButton. // class UndoableToggleEdit extends AbstractUndoableEdit {

 private JToggleButton button;
 private boolean selected;
 // Create a new edit for a JToggleButton that has just been toggled.
 public UndoableToggleEdit(JToggleButton button) {
   this.button = button;
   selected = button.isSelected();
 }
 // Return a reasonable name for this edit.
 public String getPresentationName() {
   return "Toggle " + button.getText() + " " + (selected ? "on" : "off");
 }
 // Redo by setting the button state as it was initially.
 public void redo() throws CannotRedoException {
   super.redo();
   button.setSelected(selected);
 }
 // Undo by setting the button state to the opposite value.
 public void undo() throws CannotUndoException {
   super.undo();
   button.setSelected(!selected);
 }

}

 </source>

Bind the undo action to ctl-Z

   <source lang="java">

import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.JFrame; 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.text.Document; import javax.swing.text.JTextComponent; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class Main {

 public static void main(String[] argv) {
   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   doc.addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       undo.addEdit(evt.getEdit());
     }
   });
   textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canUndo()) {
           undo.undo();
         }
       } catch (CannotUndoException e) {
       }
     }
   });
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
   JFrame frame = new JFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.add(new JScrollPane(textcomp));
   frame.setSize(380, 320);
   frame.setLocationRelativeTo(null);
   frame.setVisible(true);
 }

}

 </source>

Create an undo action and add it to the text component

   <source lang="java">

import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.event.UndoableEditEvent; import javax.swing.event.UndoableEditListener; import javax.swing.text.Document; import javax.swing.text.JTextComponent; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class Main {

 public static void main(String[] argv) {
   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   doc.addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       undo.addEdit(evt.getEdit());
     }
   });
   textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canUndo()) {
           undo.undo();
         }
       } catch (CannotUndoException e) {
       }
     }
   });
   JFrame frame = new JFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.add(new JScrollPane(textcomp));
   frame.setSize(380, 320);
   frame.setLocationRelativeTo(null);
   frame.setVisible(true);
 }

}

 </source>

Create a redo action and add it to the text component (JTextComponent)

   <source lang="java">

import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.JFrame; 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.text.Document; import javax.swing.text.JTextComponent; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class Main {

 public static void main(String[] argv) {
   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   doc.addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       undo.addEdit(evt.getEdit());
     }
   });
   textcomp.getActionMap().put("Undo", new AbstractAction("Undo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canUndo()) {
           undo.undo();
         }
       } catch (CannotUndoException e) {
       }
     }
   });
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
   textcomp.getActionMap().put("Redo", new AbstractAction("Redo") {
     public void actionPerformed(ActionEvent evt) {
       try {
         if (undo.canRedo()) {
           undo.redo();
         }
       } catch (CannotRedoException e) {
       }
     }
   });
   textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");
   JFrame frame = new JFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.add(new JScrollPane(textcomp));
   frame.setSize(380, 320);
   frame.setLocationRelativeTo(null);
   frame.setVisible(true);
 }

}

 </source>

Creating TextArea with Undo, Redo Capabilities

   <source lang="java">

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();
 }

}

 </source>

Listen for undo and redo events

   <source lang="java">

public class Main{ public static void main(String[] argv){

   JTextComponent textcomp = new JTextArea();
   final UndoManager undo = new UndoManager();
   Document doc = textcomp.getDocument();
   
   doc.addUndoableEditListener(new UndoableEditListener() {
       public void undoableEditHappened(UndoableEditEvent evt) {
           undo.addEdit(evt.getEdit());
       }
   });    
   JFrame frame = new JFrame();
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.add(new JScrollPane(textcomp));
   frame.setSize(380, 320);
   frame.setLocationRelativeTo(null);
   frame.setVisible(true);

}}

 </source>

Simple GUI demo of UndoManager and friends

   <source lang="java">

/*

* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* 
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java 
* language and environment is gratefully acknowledged.
* 
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/

import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.undo.UndoManager; /**

* Simple GUI demo of UndoManager and friends.
* 
* @author Ian Darwin http://www.darwinsys.ru/
*/

public class UndoDemo extends JFrame {

 JTextArea ta;
 UndoManager um;
 /** Simple main program that just constructs and shows the GUI */
 public static void main(String[] files) {
   new UndoDemo().setVisible(true);
 }
 /** Construct a GUI that demonstrates use of UndoManager */
 public UndoDemo() {
   Container cp = getContentPane();
   cp.add(ta = new JTextArea(20, 60), BorderLayout.CENTER);
   JPanel bp;
   cp.add(bp = new JPanel(), BorderLayout.SOUTH);
   // Create a javax.swing.undo.UndoManager; this is an amazing class that
   // keeps a Stack of UndoableEdits and lets you invoke them;
   // by registering it as a Listener on the TextComponent.Document,
   // the Document will create the UndoableEdit objects and send them
   // to the UndoManager. Between them they do ALL the work!
   um = new UndoManager();
   ta.getDocument().addUndoableEditListener(um);
   // Create the buttons
   JButton cutButton, copyButton, pasteButton, undoButton, redoButton;
   bp.add(cutButton = new JButton("Cut"));
   cutButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       ta.cut();
     }
   });
   bp.add(copyButton = new JButton("Copy"));
   copyButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       ta.copy();
     }
   });
   bp.add(pasteButton = new JButton("Paste"));
   pasteButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       ta.paste();
     }
   });
   bp.add(undoButton = new JButton("UnDo"));
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       if (um.canUndo()) {
         um.undo();
       } else {
         warn("Can"t undo");
       }
     }
   });
   bp.add(redoButton = new JButton("ReDo"));
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       if (um.canRedo()) {
         um.redo();
       } else {
         warn("Can"t redo");
       }
     }
   });
   pack();
   setDefaultCloseOperation(EXIT_ON_CLOSE);
 }
 void warn(String msg) {
   JOptionPane.showMessageDialog(this, "Warning: " + msg, "Warning",
       JOptionPane.WARNING_MESSAGE);
 }

}

 </source>

The use of StateEdit(able)

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoableToggleApp4.java //A sample app showing the use of StateEdit(able). // import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Hashtable; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JRadioButton; import javax.swing.JToggleButton; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.StateEdit; import javax.swing.undo.StateEditable; public class UndoableToggleApp4 extends JFrame implements StateEditable {

 private JToggleButton tog;
 private JCheckBox cb;
 private JRadioButton radio;
 private JButton undoButton;
 private JButton redoButton;
 private JButton startButton;
 private JButton endButton;
 private StateEdit edit;
 // Create the main frame and everything in it.
 public UndoableToggleApp4() {
   // Create some toggle buttons (and subclasses).
   tog = new JToggleButton("ToggleButton");
   cb = new JCheckBox("CheckBox");
   radio = new JRadioButton("RadioButton");
   // Add our listener to the buttons.
   SimpleListener sl = new SimpleListener();
   tog.addActionListener(sl);
   cb.addActionListener(sl);
   radio.addActionListener(sl);
   // Lay out the buttons.
   Box buttonBox = new Box(BoxLayout.Y_AXIS);
   buttonBox.add(tog);
   buttonBox.add(cb);
   buttonBox.add(radio);
   // Create undo, redo, start, and end buttons.
   startButton = new JButton("Start");
   endButton = new JButton("End");
   undoButton = new JButton("Undo");
   redoButton = new JButton("Redo");
   startButton.setEnabled(true);
   endButton.setEnabled(false);
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   // Add a listener to the start button. It creates a new StateEdit,
   // passing in this frame as the StateEditable.
   startButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       edit = new StateEdit(UndoableToggleApp4.this);
       startButton.setEnabled(false);
       endButton.setEnabled(true);
       //undoButton.setEnabled(edit.canUndo());
       //
       // NOTE: We really don"t want to be able to undo until end() is
       // pressed,
       // but StateEdit does not enforce this for us!
       undoButton.setEnabled(false);
       redoButton.setEnabled(edit.canRedo());
     }
   });
   // Add a listener to the end button. It will call end() on the
   // StateEdit.
   endButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       edit.end();
       startButton.setEnabled(true);
       endButton.setEnabled(false);
       undoButton.setEnabled(edit.canUndo());
       redoButton.setEnabled(edit.canRedo());
     }
   });
   // Add a listener to the undo button. It attempts to call undo() on the
   // current edit, then enables/disables the undo/redo buttons as
   // appropriate.
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.undo();
       } catch (CannotUndoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Add a redo listener: just like the undo listener.
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.redo();
       } catch (CannotRedoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Lay out the state/end and undo/redo buttons.
   Box undoRedoBox = new Box(BoxLayout.X_AXIS);
   undoRedoBox.add(Box.createGlue());
   undoRedoBox.add(startButton);
   undoRedoBox.add(Box.createHorizontalStrut(2));
   undoRedoBox.add(endButton);
   undoRedoBox.add(Box.createHorizontalStrut(2));
   undoRedoBox.add(undoButton);
   undoRedoBox.add(Box.createHorizontalStrut(2));
   undoRedoBox.add(redoButton);
   undoRedoBox.add(Box.createGlue());
   // Lay out the main frame.
   Container content = getContentPane();
   content.setLayout(new BorderLayout());
   content.add(buttonBox, BorderLayout.CENTER);
   content.add(undoRedoBox, BorderLayout.SOUTH);
   setSize(400, 150);
 }
 public class SimpleListener implements ActionListener {
   // When any toggle button is clicked, we turn off the undo and redo
   // buttons, reflecting the fact that we can only undo/redo the last
   // set of state changes as long as no additional changes have been made.
   public void actionPerformed(ActionEvent ev) {
     undoButton.setEnabled(false);
     redoButton.setEnabled(false);
   }
 }
 // Save the state of the app by storing the current state of the three
 // buttons. We"ll use the buttons themselves as keys and their selected
 // state as values.
 public void storeState(Hashtable ht) {
   ht.put(tog, new Boolean(tog.isSelected()));
   ht.put(cb, new Boolean(cb.isSelected()));
   ht.put(radio, new Boolean(radio.isSelected()));
 }
 // Restore state based on the values we saved when storeState() was called.
 // Note that StateEdit discards any state info that did not change from
 // between the start state and the end state, so we can"t assume that the
 // state for all 3 buttons is in the Hashtable.
 public void restoreState(Hashtable ht) {
   Boolean b1 = (Boolean) ht.get(tog);
   if (b1 != null)
     tog.setSelected(b1.booleanValue());
   Boolean b2 = (Boolean) ht.get(cb);
   if (b2 != null)
     cb.setSelected(b2.booleanValue());
   Boolean b3 = (Boolean) ht.get(radio);
   if (b3 != null)
     radio.setSelected(b3.booleanValue());
 }
 // Main program just creates the frame and displays it.
 public static void main(String[] args) {
   JFrame f = new UndoableToggleApp4();
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }

}

 </source>

The use of UndoableToggleEdit

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoableToggleApp.java //A sample app showing the use of UndoableToggleEdit. // import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JRadioButton; import javax.swing.JToggleButton; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoableEdit; public class UndoableToggleApp extends JFrame {

 private UndoableEdit edit;
 private JButton undoButton;
 private JButton redoButton;
 // Create the main frame and everything in it.
 public UndoableToggleApp() {
   // Create some toggle buttons (and subclasses)
   JToggleButton tog = new JToggleButton("ToggleButton");
   JCheckBox cb = new JCheckBox("CheckBox");
   JRadioButton radio = new JRadioButton("RadioButton");
   // Add our listener to each toggle button
   SimpleListener sl = new SimpleListener();
   tog.addActionListener(sl);
   cb.addActionListener(sl);
   radio.addActionListener(sl);
   // Layout the buttons
   Box buttonBox = new Box(BoxLayout.Y_AXIS);
   buttonBox.add(tog);
   buttonBox.add(cb);
   buttonBox.add(radio);
   // Create undo and redo buttons (initially disabled)
   undoButton = new JButton("Undo");
   redoButton = new JButton("Redo");
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   // Add a listener to the undo button. It attempts to call undo() on the
   // current edit, then enables/disables the undo/redo buttons as
   // appropriate.
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.undo();
       } catch (CannotUndoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Add a redo listener: just like the undo listener, but for redo this
   // time.
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         edit.redo();
       } catch (CannotRedoException ex) {
         ex.printStackTrace();
       } finally {
         undoButton.setEnabled(edit.canUndo());
         redoButton.setEnabled(edit.canRedo());
       }
     }
   });
   // Layout the undo/redo buttons
   Box undoRedoBox = new Box(BoxLayout.X_AXIS);
   undoRedoBox.add(Box.createGlue());
   undoRedoBox.add(undoButton);
   undoRedoBox.add(Box.createHorizontalStrut(2));
   undoRedoBox.add(redoButton);
   undoRedoBox.add(Box.createGlue());
   // Layout the main frame
   Container content = getContentPane();
   content.setLayout(new BorderLayout());
   content.add(buttonBox, BorderLayout.CENTER);
   content.add(undoRedoBox, BorderLayout.SOUTH);
   setSize(400, 150);
 }
 public class SimpleListener implements ActionListener {
   // When a toggle button is clicked, we create a new UndoableToggleEdit
   // (which replaces any previous edit). We then get the edit"s undo/redo
   // names and set the undo/redo button labels. Finally, we
   // enable/disable these buttons by asking the edit what we are
   // allowed to do.
   public void actionPerformed(ActionEvent ev) {
     JToggleButton tb = (JToggleButton) ev.getSource();
     edit = new UndoableToggleEdit(tb);
     undoButton.setText(edit.getUndoPresentationName());
     redoButton.setText(edit.getRedoPresentationName());
     undoButton.getParent().validate();
     undoButton.setEnabled(edit.canUndo());
     redoButton.setEnabled(edit.canRedo());
   }
 }
 // Main program just creates the frame and displays it.
 public static void main(String[] args) {
   JFrame f = new UndoableToggleApp();
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }

} //UndoableToggleEdit.java //An UndoableEdit used to undo the pressing of a JToggleButton. // class UndoableToggleEdit extends AbstractUndoableEdit {

 private JToggleButton button;
 private boolean selected;
 // Create a new edit for a JToggleButton that has just been toggled.
 public UndoableToggleEdit(JToggleButton button) {
   this.button = button;
   selected = button.isSelected();
 }
 // Return a reasonable name for this edit.
 public String getPresentationName() {
   return "Toggle " + button.getText() + " " + (selected ? "on" : "off");
 }
 // Redo by setting the button state as it was initially.
 public void redo() throws CannotRedoException {
   super.redo();
   button.setSelected(selected);
 }
 // Undo by setting the button state to the opposite value.
 public void undo() throws CannotUndoException {
   super.undo();
   button.setSelected(!selected);
 }

}

 </source>

The use of UndoManager

   <source lang="java">

/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O"Reilly

/

// UndoableToggleApp3.java //A sample app showing the use of UndoManager. // import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JToggleButton; import javax.swing.event.UndoableEditEvent; import javax.swing.event.UndoableEditListener; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class UndoableToggleApp3 extends JFrame {

 private UndoManager manager = new UndoManager();
 private JButton undoButton;
 private JButton redoButton;
 // Create the main frame and everything in it.
 public UndoableToggleApp3() {
   // Create some toggle buttons.
   UndoableJToggleButton tog1 = new UndoableJToggleButton("One");
   UndoableJToggleButton tog2 = new UndoableJToggleButton("Two");
   UndoableJToggleButton tog3 = new UndoableJToggleButton("Three");
   // Add our listener to each toggle button.
   SimpleUEListener sl = new SimpleUEListener();
   tog1.addUndoableEditListener(sl);
   tog2.addUndoableEditListener(sl);
   tog3.addUndoableEditListener(sl);
   // Lay out the buttons.
   Box buttonBox = new Box(BoxLayout.Y_AXIS);
   buttonBox.add(tog1);
   buttonBox.add(tog2);
   buttonBox.add(tog3);
   // Create undo and redo buttons (initially disabled).
   undoButton = new JButton("Undo");
   redoButton = new JButton("Redo");
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   // Add a listener to the undo button. It attempts to call undo() on the
   // UndoManager, then enables/disables the undo/redo buttons as
   // appropriate.
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         manager.undo();
       } catch (CannotUndoException ex) {
         ex.printStackTrace();
       } finally {
         updateButtons();
       }
     }
   });
   // Add a redo listener: just like the undo listener.
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ev) {
       try {
         manager.redo();
       } catch (CannotRedoException ex) {
         ex.printStackTrace();
       } finally {
         updateButtons();
       }
     }
   });
   // Lay out the undo/redo buttons.
   Box undoRedoBox = new Box(BoxLayout.X_AXIS);
   undoRedoBox.add(Box.createGlue());
   undoRedoBox.add(undoButton);
   undoRedoBox.add(Box.createHorizontalStrut(2));
   undoRedoBox.add(redoButton);
   undoRedoBox.add(Box.createGlue());
   // Lay out the main frame.
   getContentPane().setLayout(new BorderLayout());
   getContentPane().add(buttonBox, BorderLayout.CENTER);
   getContentPane().add(undoRedoBox, BorderLayout.SOUTH);
   setSize(400, 150);
 }
 public class SimpleUEListener implements UndoableEditListener {
   // When an UndoableEditEvent is generated (each time one of the buttons
   // is pressed), we add it to the UndoManager and then get the manager"s
   // undo/redo names and set the undo/redo button labels. Finally, we
   // enable/disable these buttons by asking the manager what we are
   // allowed to do.
   public void undoableEditHappened(UndoableEditEvent ev) {
     manager.addEdit(ev.getEdit());
     updateButtons();
   }
 }
 // Method to set the text and state of the undo/redo buttons.
 protected void updateButtons() {
   undoButton.setText(manager.getUndoPresentationName());
   redoButton.setText(manager.getRedoPresentationName());
   undoButton.getParent().validate();
   undoButton.setEnabled(manager.canUndo());
   redoButton.setEnabled(manager.canRedo());
 }
 // Main program just creates the frame and displays it.
 public static void main(String[] args) {
   JFrame f = new UndoableToggleApp3();
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }

} //UndoableJToggleButton.java //Sample undoable toggle button class. Supports only a single listener to //simplify the code. // class UndoableJToggleButton extends JToggleButton {

 private UndoableEditListener listener;
 // For this example, we"ll just provide one constructor . . .
 public UndoableJToggleButton(String txt) {
   super(txt);
 }
 // Set the UndoableEditListener.
 public void addUndoableEditListener(UndoableEditListener l) {
   listener = l; // Should ideally throw an exception if listener != null
 }
 // Remove the UndoableEditListener.
 public void removeUndoableEditListener(UndoableEditListener l) {
   listener = null;
 }
 // We override this method to call the super implementation first (to fire
 // the
 // action event) and then fire a new UndoableEditEvent to our listener.
 protected void fireActionPerformed(ActionEvent ev) {
   // Fire the ActionEvent as usual.
   super.fireActionPerformed(ev);
   if (listener != null) {
     listener.undoableEditHappened(new UndoableEditEvent(this,
         new UndoableToggleEdit(this)));
   }
 }

} //UndoableToggleEdit.java //An UndoableEdit used to undo the pressing of a JToggleButton. // class UndoableToggleEdit extends AbstractUndoableEdit {

 private JToggleButton button;
 private boolean selected;
 // Create a new edit for a JToggleButton that has just been toggled.
 public UndoableToggleEdit(JToggleButton button) {
   this.button = button;
   selected = button.isSelected();
 }
 // Return a reasonable name for this edit.
 public String getPresentationName() {
   return "Toggle " + button.getText() + " " + (selected ? "on" : "off");
 }
 // Redo by setting the button state as it was initially.
 public void redo() throws CannotRedoException {
   super.redo();
   button.setSelected(selected);
 }
 // Undo by setting the button state to the opposite value.
 public void undo() throws CannotUndoException {
   super.undo();
   button.setSelected(!selected);
 }

}

 </source>

Undoable Drawing Panel 2

   <source lang="java">

/* Definitive Guide to Swing for Java 2, Second Edition By John Zukowski ISBN: 1-893115-78-X Publisher: APress

/

import java.awt.BorderLayout; import java.awt.ruponent; import java.awt.Container; import java.awt.Graphics; import java.awt.Polygon; import java.awt.event.ActionEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.util.Hashtable; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JToolBar; import javax.swing.event.UndoableEditListener; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.StateEdit; import javax.swing.undo.StateEditable; import javax.swing.undo.UndoManager; import javax.swing.undo.UndoableEditSupport; public class UndoableDrawingPanel2 extends JPanel implements StateEditable {

 private static String POLYGON_KEY = "Polygon";
 UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);
 Polygon polygon = new Polygon();
 public UndoableDrawingPanel2() {
   MouseListener mouseListener = new MouseAdapter() {
     public void mouseReleased(MouseEvent mouseEvent) {
       StateEdit stateEdit = new StateEdit(UndoableDrawingPanel2.this);
       polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());
       stateEdit.end();
       undoableEditSupport.postEdit(stateEdit);
       repaint();
     }
   };
   addMouseListener(mouseListener);
 }
 public void addUndoableEditListener(
     UndoableEditListener undoableEditListener) {
   undoableEditSupport.addUndoableEditListener(undoableEditListener);
 }
 public void removeUndoableEditListener(
     UndoableEditListener undoableEditListener) {
   undoableEditSupport.removeUndoableEditListener(undoableEditListener);
 }
 public void storeState(Hashtable state) {
   state.put(POLYGON_KEY, getPolygon());
 }
 public void restoreState(Hashtable state) {
   Polygon polygon = (Polygon) state.get(POLYGON_KEY);
   if (polygon != null) {
     setPolygon(polygon);
   }
 }
 public void setPolygon(Polygon newValue) {
   polygon = newValue;
   repaint();
 }
 public Polygon getPolygon() {
   Polygon returnValue;
   if (polygon.npoints == 0) {
     returnValue = new Polygon();
   } else {
     returnValue = new Polygon(polygon.xpoints, polygon.ypoints,
         polygon.npoints);
   }
   return returnValue;
 }
 protected void paintComponent(Graphics g) {
   super.paintComponent(g);
   g.drawPolygon(polygon);
 }
 public static void main(String args[]) {
   JFrame frame = new JFrame("Drawing Sample2");
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   UndoableDrawingPanel2 drawingPanel = new UndoableDrawingPanel2();
   UndoManager manager = new UndoManager();
   drawingPanel.addUndoableEditListener(manager);
   JToolBar toolbar = new JToolBar();
   toolbar.add(UndoManagerHelper.getUndoAction(manager));
   toolbar.add(UndoManagerHelper.getRedoAction(manager));
   Container content = frame.getContentPane();
   content.add(toolbar, BorderLayout.NORTH);
   content.add(drawingPanel, BorderLayout.CENTER);
   frame.setSize(300, 150);
   frame.setVisible(true);
 }

} class UndoManagerHelper {

 public static Action getUndoAction(UndoManager manager, String label) {
   return new UndoAction(manager, label);
 }
 public static Action getUndoAction(UndoManager manager) {
   return new UndoAction(manager, "Undo");
 }
 public static Action getRedoAction(UndoManager manager, String label) {
   return new RedoAction(manager, label);
 }
 public static Action getRedoAction(UndoManager manager) {
   return new RedoAction(manager, "Redo");
 }
 private abstract static class UndoRedoAction extends AbstractAction {
   UndoManager undoManager = new UndoManager();
   String errorMessage = "Cannot undo";
   String errorTitle = "Undo Problem";
   protected UndoRedoAction(UndoManager manager, String name) {
     super(name);
     undoManager = manager;
   }
   public void setErrorMessage(String newValue) {
     errorMessage = newValue;
   }
   public void setErrorTitle(String newValue) {
     errorTitle = newValue;
   }
   protected void showMessage(Object source) {
     if (source instanceof Component) {
       JOptionPane.showMessageDialog((Component) source, errorMessage,
           errorTitle, JOptionPane.WARNING_MESSAGE);
     } else {
       System.err.println(errorMessage);
     }
   }
 }
 public static class UndoAction extends UndoRedoAction {
   public UndoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot undo");
     setErrorTitle("Undo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.undo();
     } catch (CannotUndoException cannotUndoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }
 public static class RedoAction extends UndoRedoAction {
   String errorMessage = "Cannot redo";
   String errorTitle = "Redo Problem";
   public RedoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot redo");
     setErrorTitle("Redo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.redo();
     } catch (CannotRedoException cannotRedoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }

}

 </source>

Undo Drawing

   <source lang="java">

/* Definitive Guide to Swing for Java 2, Second Edition By John Zukowski ISBN: 1-893115-78-X Publisher: APress

/

import java.awt.BorderLayout; import java.awt.ruponent; import java.awt.Container; import java.awt.Graphics; import java.awt.Polygon; import java.awt.event.ActionEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JToolBar; import javax.swing.event.UndoableEditListener; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; import javax.swing.undo.UndoableEditSupport; public class UndoDrawing {

 public static void main(String args[]) {
   JFrame frame = new JFrame("Drawing Sample");
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();
   UndoManager manager = new UndoManager();
   drawingPanel.addUndoableEditListener(manager);
   JToolBar toolbar = new JToolBar();
   toolbar.add(UndoManagerHelper.getUndoAction(manager));
   toolbar.add(UndoManagerHelper.getRedoAction(manager));
   Container content = frame.getContentPane();
   content.add(toolbar, BorderLayout.NORTH);
   content.add(drawingPanel, BorderLayout.CENTER);
   frame.setSize(300, 150);
   frame.setVisible(true);
 }

} class UndoableDrawingPanel extends JPanel {

 UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);
 Polygon polygon = new Polygon();
 public UndoableDrawingPanel() {
   MouseListener mouseListener = new MouseAdapter() {
     public void mouseReleased(MouseEvent mouseEvent) {
       undoableEditSupport.postEdit(new UndoableDrawEdit(
           UndoableDrawingPanel.this));
       polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());
       repaint();
     }
   };
   addMouseListener(mouseListener);
 }
 public void addUndoableEditListener(
     UndoableEditListener undoableEditListener) {
   undoableEditSupport.addUndoableEditListener(undoableEditListener);
 }
 public void removeUndoableEditListener(
     UndoableEditListener undoableEditListener) {
   undoableEditSupport.removeUndoableEditListener(undoableEditListener);
 }
 public void setPolygon(Polygon newValue) {
   polygon = newValue;
   repaint();
 }
 public Polygon getPolygon() {
   Polygon returnValue;
   if (polygon.npoints == 0) {
     returnValue = new Polygon();
   } else {
     returnValue = new Polygon(polygon.xpoints, polygon.ypoints,
         polygon.npoints);
   }
   return returnValue;
 }
 protected void paintComponent(Graphics g) {
   super.paintComponent(g);
   g.drawPolygon(polygon);
 }

} class UndoManagerHelper {

 public static Action getUndoAction(UndoManager manager, String label) {
   return new UndoAction(manager, label);
 }
 public static Action getUndoAction(UndoManager manager) {
   return new UndoAction(manager, "Undo");
 }
 public static Action getRedoAction(UndoManager manager, String label) {
   return new RedoAction(manager, label);
 }
 public static Action getRedoAction(UndoManager manager) {
   return new RedoAction(manager, "Redo");
 }
 private abstract static class UndoRedoAction extends AbstractAction {
   UndoManager undoManager = new UndoManager();
   String errorMessage = "Cannot undo";
   String errorTitle = "Undo Problem";
   protected UndoRedoAction(UndoManager manager, String name) {
     super(name);
     undoManager = manager;
   }
   public void setErrorMessage(String newValue) {
     errorMessage = newValue;
   }
   public void setErrorTitle(String newValue) {
     errorTitle = newValue;
   }
   protected void showMessage(Object source) {
     if (source instanceof Component) {
       JOptionPane.showMessageDialog((Component) source, errorMessage,
           errorTitle, JOptionPane.WARNING_MESSAGE);
     } else {
       System.err.println(errorMessage);
     }
   }
 }
 public static class UndoAction extends UndoRedoAction {
   public UndoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot undo");
     setErrorTitle("Undo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.undo();
     } catch (CannotUndoException cannotUndoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }
 public static class RedoAction extends UndoRedoAction {
   String errorMessage = "Cannot redo";
   String errorTitle = "Redo Problem";
   public RedoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot redo");
     setErrorTitle("Redo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.redo();
     } catch (CannotRedoException cannotRedoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }

} class UndoableDrawEdit extends AbstractUndoableEdit {

 UndoableDrawingPanel panel;
 Polygon polygon, savedPolygon;
 public UndoableDrawEdit(UndoableDrawingPanel panel) {
   this.panel = panel;
   polygon = panel.getPolygon();
 }
 public String getPresentationName() {
   return "Polygon of size " + polygon.npoints;
 }
 public void redo() throws CannotRedoException {
   super.redo();
   if (savedPolygon == null) {
     // Should never get here, as super() doesn"t permit redoing
     throw new CannotRedoException();
   } else {
     panel.setPolygon(savedPolygon);
     savedPolygon = null;
   }
 }
 public void undo() throws CannotUndoException {
   super.undo();
   savedPolygon = panel.getPolygon();
   panel.setPolygon(polygon);
 }

}

 </source>

Undo Example 1

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.undo.*; public class UndoExample1 extends JFrame {

 public UndoExample1() {
   super("Undo/Redo Example 1");
 
   pane = new JTextPane();
   pane.setEditable(true);    // Editable
   getContentPane().add(new JScrollPane(pane), "Center");
   // Add a menu bar
   menuBar = new JMenuBar();
   setJMenuBar(menuBar);
   // Populate the menu bar
   createMenuBar();
 }
 public void createMenuBar() {
   // Remove the existing menu items
   int count = menuBar.getMenuCount();
   for (int i = 0; i < count; i++) {
     menuBar.remove(menuBar.getMenu(0));
   }
   // Build the new menu.
   Action[] actions = pane.getActions();
   Hashtable actionHash = new Hashtable();
   count = actions.length;
   for (int i = 0; i < count; i++) {
     actionHash.put(actions[i].getValue(Action.NAME), actions[i]);
   }
   // Add the font menu
   JMenu menu = MenuBuilder.buildMenu("Font", fontSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
   // Add the alignment menu
   menu = MenuBuilder.buildMenu("Align", alignSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
 }
 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   JFrame f = new UndoExample1();
   f.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent evt) {
       System.exit(0);
     }
   });
   f.setSize(250, 300);
   f.setVisible(true);
   // Create and show a frame monitoring undoable edits
   JFrame undoMonitor = new JFrame("Undo Monitor");
   final JTextArea textArea = new JTextArea();
   textArea.setEditable(false);
   undoMonitor.getContentPane().add(new JScrollPane(textArea));
   undoMonitor.setBounds(f.getLocation().x + f.getSize().width, 
             f.getLocation().y, 400, 200);
   undoMonitor.setVisible(true);
   pane.getDocument().addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       UndoableEdit edit = evt.getEdit();
       textArea.append(edit.getPresentationName() + "(" +
               edit.toString() + ")\n");
     }
   });
   
   // Create and show a frame monitoring document edits
   JFrame editMonitor = new JFrame("Edit Monitor");
   final JTextArea textArea2 = new JTextArea();
   textArea2.setEditable(false);
   editMonitor.getContentPane().add(new JScrollPane(textArea2));
   editMonitor.setBounds(undoMonitor.getLocation().x, 
         undoMonitor.getLocation().y + undoMonitor.getSize().height,
         400, 200);
   editMonitor.setVisible(true);
   pane.getDocument().addDocumentListener(new DocumentListener() {
     public void changedUpdate(DocumentEvent evt) {
       textArea2.append("Attribute change\n");
     }
     public void insertUpdate(DocumentEvent evt) {
       textArea2.append("Text insertion\n");
     }
     public void removeUpdate(DocumentEvent evt) {
       textArea2.append("Text removal\n");
     }
   });
 }
 private static JTextPane pane;
 private static JMenuBar menuBar;
 private static MenuSpec[] sizeSpec = new MenuSpec[] {
     new MenuSpec("Size 8",  "font-size-8"),
     new MenuSpec("Size 10", "font-size-10"),
     new MenuSpec("Size 12", "font-size-12"),
     new MenuSpec("Size 14", "font-size-14"),
     new MenuSpec("Size 16", "font-size-16"),
     new MenuSpec("Size 18", "font-size-18"),
     new MenuSpec("Size 24", "font-size-24"),
     new MenuSpec("Size 36", "font-size-36"),
     new MenuSpec("Size 48", "font-size-48")          
 };
 private static MenuSpec[] familySpec = new MenuSpec[] {
     new MenuSpec("Sans Serif", "font-family-SansSerif"),
     new MenuSpec("Monospaced", "font-family-Monospaced"),
     new MenuSpec("Serif", "font-family-Serif")
 };
 private static MenuSpec[] styleSpec = new MenuSpec[] {
     new MenuSpec("Bold", "font-bold"),
     new MenuSpec("Italics", "font-italic"),
     new MenuSpec("Underline", "font-underline")
 };
 // Menu definitions for fonts
 private static MenuSpec[] fontSpec = new MenuSpec[] {
     new MenuSpec("Size", sizeSpec),
     new MenuSpec("Family", familySpec),
     new MenuSpec("Style", styleSpec)
 };
 // Alignment
 private static MenuSpec[] alignSpec = new MenuSpec[] {
     new MenuSpec("Left", "left-justify"),
     new MenuSpec("Center", "center-justify"),
     new MenuSpec("Right", "right-justify")
 };

}

class MenuSpec {

 public MenuSpec(String name, MenuSpec[] subMenus) {
   this.name = name;
   this.subMenus = subMenus;
 }
 public MenuSpec(String name, String actionName) {
   this.name = name;
   this.actionName = actionName;
 }
 public MenuSpec(String name, Action action) {
   this.name = name;
   this.action = action;
 }
 public boolean isSubMenu() {
   return subMenus != null;
 }
 public boolean isAction() {
   return action != null;
 }
 public String getName() {
   return name;
 }
 public MenuSpec[] getSubMenus() {
   return subMenus;
 }
 public String getActionName() {
   return actionName;
 }
 public Action getAction() {
   return action;
 }
 private String name;
 private String actionName;
 private Action action;
 private MenuSpec[] subMenus;

}

class MenuBuilder {

 public static JMenu buildMenu(String name, MenuSpec[] menuSpecs,
     Hashtable actions) {
   int count = menuSpecs.length;
   JMenu menu = new JMenu(name);
   for (int i = 0; i < count; i++) {
     MenuSpec spec = menuSpecs[i];
     if (spec.isSubMenu()) {
       // Recurse to handle a sub menu
       JMenu subMenu = buildMenu(spec.getName(), spec.getSubMenus(),
           actions);
       if (subMenu != null) {
         menu.add(subMenu);
       }
     } else if (spec.isAction()) {
       // It"s an Action - add it directly to the menu
       menu.add(spec.getAction());
     } else {
       // It"s an action name - add it if possible
       String actionName = spec.getActionName();
       Action targetAction = (Action) actions.get(actionName);
       // Create the menu item
       JMenuItem menuItem = menu.add(spec.getName());
       if (targetAction != null) {
         // The editor kit knows the action
         menuItem.addActionListener(targetAction);
       } else {
         // Action not known - disable the menu item
         menuItem.setEnabled(false);
       }
     }
   }
   // Return null if nothing was added to the menu.
   if (menu.getMenuComponentCount() == 0) {
     menu = null;
   }
   return menu;
 }

}

 </source>

Undo Example 2

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.BorderLayout; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.Hashtable; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JTextPane; import javax.swing.KeyStroke; import javax.swing.UIManager; import javax.swing.event.DocumentEvent; import javax.swing.event.DocumentListener; 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; import javax.swing.undo.UndoableEdit; public class UndoExample2 extends JFrame {

 public UndoExample2() {
   super("Undo/Redo Example 2");
   pane = new JTextPane();
   pane.setEditable(true); // Editable
   getContentPane().add(new JScrollPane(pane), BorderLayout.CENTER);
   // Add a menu bar
   menuBar = new JMenuBar();
   setJMenuBar(menuBar);
   // Populate the menu bar
   createMenuBar();
   // Create the undo manager and actions
   UndoManager manager = new UndoManager();
   pane.getDocument().addUndoableEditListener(manager);
   Action undoAction = new UndoAction(manager);
   Action redoAction = new RedoAction(manager);
   // Add the actions to buttons
   JPanel panel = new JPanel();
   JButton undoButton = new JButton("Undo");
   JButton redoButton = new JButton("Redo");
   undoButton.addActionListener(undoAction);
   redoButton.addActionListener(redoAction);
   panel.add(undoButton);
   panel.add(redoButton);
   getContentPane().add(panel, BorderLayout.SOUTH);
   // Assign the actions to keys
   pane.registerKeyboardAction(undoAction, KeyStroke.getKeyStroke(
       KeyEvent.VK_Z, InputEvent.CTRL_MASK), JComponent.WHEN_FOCUSED);
   pane.registerKeyboardAction(redoAction, KeyStroke.getKeyStroke(
       KeyEvent.VK_Y, InputEvent.CTRL_MASK), JComponent.WHEN_FOCUSED);
 }
 public void createMenuBar() {
   // Remove the existing menu items
   int count = menuBar.getMenuCount();
   for (int i = 0; i < count; i++) {
     menuBar.remove(menuBar.getMenu(0));
   }
   // Build the new menu.
   Action[] actions = pane.getActions();
   Hashtable actionHash = new Hashtable();
   count = actions.length;
   for (int i = 0; i < count; i++) {
     actionHash.put(actions[i].getValue(Action.NAME), actions[i]);
   }
   // Add the font menu
   JMenu menu = MenuBuilder.buildMenu("Font", fontSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
   // Add the alignment menu
   menu = MenuBuilder.buildMenu("Align", alignSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
 }
 // The Undo action
 public class UndoAction extends AbstractAction {
   public UndoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.undo();
     } catch (CannotUndoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 // The Redo action
 public class RedoAction extends AbstractAction {
   public RedoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.redo();
     } catch (CannotRedoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   JFrame f = new UndoExample2();
   f.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent evt) {
       System.exit(0);
     }
   });
   f.setSize(250, 300);
   f.setVisible(true);
   // Create and show a frame monitoring undoable edits
   JFrame undoMonitor = new JFrame("Undo Monitor");
   final JTextArea textArea = new JTextArea();
   textArea.setEditable(false);
   undoMonitor.getContentPane().add(new JScrollPane(textArea));
   undoMonitor.setBounds(f.getLocation().x + f.getSize().width, f
       .getLocation().y, 400, 200);
   undoMonitor.setVisible(true);
   pane.getDocument().addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       UndoableEdit edit = evt.getEdit();
       textArea.append(edit.getPresentationName() + "("
           + edit.toString() + ")\n");
     }
   });
   // Create and show a frame monitoring document edits
   JFrame editMonitor = new JFrame("Edit Monitor");
   final JTextArea textArea2 = new JTextArea();
   textArea2.setEditable(false);
   editMonitor.getContentPane().add(new JScrollPane(textArea2));
   editMonitor.setBounds(undoMonitor.getLocation().x, undoMonitor
       .getLocation().y
       + undoMonitor.getSize().height, 400, 200);
   editMonitor.setVisible(true);
   pane.getDocument().addDocumentListener(new DocumentListener() {
     public void changedUpdate(DocumentEvent evt) {
       textArea2.append("Attribute change\n");
     }
     public void insertUpdate(DocumentEvent evt) {
       textArea2.append("Text insertion\n");
     }
     public void removeUpdate(DocumentEvent evt) {
       textArea2.append("Text removal\n");
     }
   });
 }
 private static JTextPane pane;
 private static JMenuBar menuBar;
 private static MenuSpec[] sizeSpec = new MenuSpec[] {
     new MenuSpec("Size 8", "font-size-8"),
     new MenuSpec("Size 10", "font-size-10"),
     new MenuSpec("Size 12", "font-size-12"),
     new MenuSpec("Size 14", "font-size-14"),
     new MenuSpec("Size 16", "font-size-16"),
     new MenuSpec("Size 18", "font-size-18"),
     new MenuSpec("Size 24", "font-size-24"),
     new MenuSpec("Size 36", "font-size-36"),
     new MenuSpec("Size 48", "font-size-48") };
 private static MenuSpec[] familySpec = new MenuSpec[] {
     new MenuSpec("Sans Serif", "font-family-SansSerif"),
     new MenuSpec("Monospaced", "font-family-Monospaced"),
     new MenuSpec("Serif", "font-family-Serif") };
 private static MenuSpec[] styleSpec = new MenuSpec[] {
     new MenuSpec("Bold", "font-bold"),
     new MenuSpec("Italics", "font-italic"),
     new MenuSpec("Underline", "font-underline") };
 // Menu definitions for fonts
 private static MenuSpec[] fontSpec = new MenuSpec[] {
     new MenuSpec("Size", sizeSpec), new MenuSpec("Family", familySpec),
     new MenuSpec("Style", styleSpec) };
 // Alignment
 private static MenuSpec[] alignSpec = new MenuSpec[] {
     new MenuSpec("Left", "left-justify"),
     new MenuSpec("Center", "center-justify"),
     new MenuSpec("Right", "right-justify") };

} class MenuSpec {

 public MenuSpec(String name, MenuSpec[] subMenus) {
   this.name = name;
   this.subMenus = subMenus;
 }
 public MenuSpec(String name, String actionName) {
   this.name = name;
   this.actionName = actionName;
 }
 public MenuSpec(String name, Action action) {
   this.name = name;
   this.action = action;
 }
 public boolean isSubMenu() {
   return subMenus != null;
 }
 public boolean isAction() {
   return action != null;
 }
 public String getName() {
   return name;
 }
 public MenuSpec[] getSubMenus() {
   return subMenus;
 }
 public String getActionName() {
   return actionName;
 }
 public Action getAction() {
   return action;
 }
 private String name;
 private String actionName;
 private Action action;
 private MenuSpec[] subMenus;

} class MenuBuilder {

 public static JMenu buildMenu(String name, MenuSpec[] menuSpecs,
     Hashtable actions) {
   int count = menuSpecs.length;
   JMenu menu = new JMenu(name);
   for (int i = 0; i < count; i++) {
     MenuSpec spec = menuSpecs[i];
     if (spec.isSubMenu()) {
       // Recurse to handle a sub menu
       JMenu subMenu = buildMenu(spec.getName(), spec.getSubMenus(),
           actions);
       if (subMenu != null) {
         menu.add(subMenu);
       }
     } else if (spec.isAction()) {
       // It"s an Action - add it directly to the menu
       menu.add(spec.getAction());
     } else {
       // It"s an action name - add it if possible
       String actionName = spec.getActionName();
       Action targetAction = (Action) actions.get(actionName);
       // Create the menu item
       JMenuItem menuItem = menu.add(spec.getName());
       if (targetAction != null) {
         // The editor kit knows the action
         menuItem.addActionListener(targetAction);
       } else {
         // Action not known - disable the menu item
         menuItem.setEnabled(false);
       }
     }
   }
   // Return null if nothing was added to the menu.
   if (menu.getMenuComponentCount() == 0) {
     menu = null;
   }
   return menu;
 }

}

 </source>

Undo Example 3

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.BorderLayout; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTree; import javax.swing.KeyStroke; import javax.swing.UIManager; import javax.swing.event.UndoableEditListener; import javax.swing.tree.DefaultMutableTreeNode; import javax.swing.tree.TreeNode; import javax.swing.tree.TreePath; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; import javax.swing.undo.UndoableEditSupport; public class UndoExample3 extends JFrame {

 public UndoExample3() {
   super("Undo/Redo Example 3");
   DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("root");
   DefaultMutableTreeNode node = new DefaultMutableTreeNode("Apollo 8");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Borman"));
   node.add(new DefaultMutableTreeNode("Lovell"));
   node.add(new DefaultMutableTreeNode("Anders"));
   node = new DefaultMutableTreeNode("Apollo 11");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Armstrong"));
   node.add(new DefaultMutableTreeNode("Aldrin"));
   node.add(new DefaultMutableTreeNode("Collins"));
   node = new DefaultMutableTreeNode("Apollo 12");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Conrad"));
   node.add(new DefaultMutableTreeNode("Gordon"));
   node.add(new DefaultMutableTreeNode("Bean"));
   UndoableTree tree = new UndoableTree(rootNode);
   getContentPane().add(new JScrollPane(tree), BorderLayout.CENTER);
   // Create the undo manager and actions
   UndoManager manager = new UndoManager();
   tree.addUndoableEditListener(manager);
   Action undoAction = new UndoAction(manager);
   Action redoAction = new RedoAction(manager);
   // Add the actions to buttons
   JPanel panel = new JPanel();
   JButton undoButton = new JButton("Undo");
   JButton redoButton = new JButton("Redo");
   undoButton.addActionListener(undoAction);
   redoButton.addActionListener(redoAction);
   panel.add(undoButton);
   panel.add(redoButton);
   getContentPane().add(panel, BorderLayout.SOUTH);
   // Assign the actions to keys
   ((JComponent) getContentPane()).registerKeyboardAction(undoAction,
       KeyStroke.getKeyStroke(KeyEvent.VK_Z, InputEvent.CTRL_MASK),
       JComponent.WHEN_IN_FOCUSED_WINDOW);
   ((JComponent) getContentPane()).registerKeyboardAction(redoAction,
       KeyStroke.getKeyStroke(KeyEvent.VK_Y, InputEvent.CTRL_MASK),
       JComponent.WHEN_IN_FOCUSED_WINDOW);
 }
 // The Undo action
 public class UndoAction extends AbstractAction {
   public UndoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.undo();
     } catch (CannotUndoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 // The Redo action
 public class RedoAction extends AbstractAction {
   public RedoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.redo();
     } catch (CannotRedoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   JFrame f = new UndoExample3();
   f.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent evt) {
       System.exit(0);
     }
   });
   f.pack();
   f.setVisible(true);
 }

} class UndoableTree extends JTree {

 // Only one constructor for brevity
 public UndoableTree(TreeNode root) {
   super(root);
 }
 public void addUndoableEditListener(UndoableEditListener l) {
   support.addUndoableEditListener(l);
 }
 public void removeUndoableEditListener(UndoableEditListener l) {
   support.removeUndoableEditListener(l);
 }
 public void collapsePath(TreePath path) {
   boolean wasExpanded = isExpanded(path);
   super.collapsePath(path);
   boolean isExpanded = isExpanded(path);
   if (isExpanded != wasExpanded) {
     support.postEdit(new CollapseEdit(path));
   }
 }
 public void expandPath(TreePath path) {
   boolean wasExpanded = isExpanded(path);
   super.expandPath(path);
   boolean isExpanded = isExpanded(path);
   if (isExpanded != wasExpanded) {
     support.postEdit(new ExpandEdit(path));
   }
 }
 private void undoExpansion(TreePath path) {
   super.collapsePath(path);
 }
 private void undoCollapse(TreePath path) {
   super.expandPath(path);
 }
 private class CollapseEdit extends AbstractUndoableEdit {
   public CollapseEdit(TreePath path) {
     this.path = path;
   }
   public void undo() throws CannotUndoException {
     super.undo();
     UndoableTree.this.undoCollapse(path);
   }
   public void redo() throws CannotRedoException {
     super.redo();
     UndoableTree.this.undoExpansion(path);
   }
   public String getPresentationName() {
     return "node collapse";
   }
   private TreePath path;
 }
 private class ExpandEdit extends AbstractUndoableEdit {
   public ExpandEdit(TreePath path) {
     this.path = path;
   }
   public void undo() throws CannotUndoException {
     super.undo();
     UndoableTree.this.undoExpansion(path);
   }
   public void redo() throws CannotRedoException {
     super.redo();
     UndoableTree.this.undoCollapse(path);
   }
   public String getPresentationName() {
     return "node expansion";
   }
   private TreePath path;
 }
 private UndoableEditSupport support = new UndoableEditSupport(this);

}

 </source>

Undo Example 4

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.BorderLayout; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTree; import javax.swing.KeyStroke; import javax.swing.UIManager; import javax.swing.event.UndoableEditListener; import javax.swing.tree.DefaultMutableTreeNode; import javax.swing.tree.TreeNode; import javax.swing.tree.TreePath; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; import javax.swing.undo.UndoableEditSupport; public class UndoExample4 extends JFrame {

 public UndoExample4() {
   super("Undo/Redo Example 4");
   DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("root");
   DefaultMutableTreeNode node = new DefaultMutableTreeNode("Apollo 8");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Borman"));
   node.add(new DefaultMutableTreeNode("Lovell"));
   node.add(new DefaultMutableTreeNode("Anders"));
   node = new DefaultMutableTreeNode("Apollo 11");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Armstrong"));
   node.add(new DefaultMutableTreeNode("Aldrin"));
   node.add(new DefaultMutableTreeNode("Collins"));
   node = new DefaultMutableTreeNode("Apollo 12");
   rootNode.add(node);
   node.add(new DefaultMutableTreeNode("Conrad"));
   node.add(new DefaultMutableTreeNode("Gordon"));
   node.add(new DefaultMutableTreeNode("Bean"));
   UndoableTree2 tree = new UndoableTree2(rootNode);
   getContentPane().add(new JScrollPane(tree), BorderLayout.CENTER);
   // Create the undo manager and actions
   UndoManager manager = new UndoManager();
   tree.addUndoableEditListener(manager);
   Action undoAction = new UndoAction(manager);
   Action redoAction = new RedoAction(manager);
   // Add the actions to buttons
   JPanel panel = new JPanel();
   JButton undoButton = new JButton("Undo");
   JButton redoButton = new JButton("Redo");
   undoButton.addActionListener(undoAction);
   redoButton.addActionListener(redoAction);
   panel.add(undoButton);
   panel.add(redoButton);
   getContentPane().add(panel, BorderLayout.SOUTH);
   // Assign the actions to keys
   ((JComponent) getContentPane()).registerKeyboardAction(undoAction,
       KeyStroke.getKeyStroke(KeyEvent.VK_Z, InputEvent.CTRL_MASK),
       JComponent.WHEN_IN_FOCUSED_WINDOW);
   ((JComponent) getContentPane()).registerKeyboardAction(redoAction,
       KeyStroke.getKeyStroke(KeyEvent.VK_Y, InputEvent.CTRL_MASK),
       JComponent.WHEN_IN_FOCUSED_WINDOW);
 }
 // The Undo action
 public class UndoAction extends AbstractAction {
   public UndoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.undo();
     } catch (CannotUndoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 // The Redo action
 public class RedoAction extends AbstractAction {
   public RedoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.redo();
     } catch (CannotRedoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   JFrame f = new UndoExample4();
   f.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent evt) {
       System.exit(0);
     }
   });
   f.pack();
   f.setVisible(true);
 }

} class UndoableTree2 extends JTree {

 public UndoableTree2(TreeNode root) {
   super(root);
 }
 public void addUndoableEditListener(UndoableEditListener l) {
   support.addUndoableEditListener(l);
 }
 public void removeUndoableEditListener(UndoableEditListener l) {
   support.removeUndoableEditListener(l);
 }
 public void collapsePath(TreePath path) {
   boolean wasExpanded = isExpanded(path);
   TreePath[] selections = getSelectionPaths();
   super.collapsePath(path);
   boolean isExpanded = isExpanded(path);
   if (isExpanded != wasExpanded) {
     TreePath[] newSelections = getSelectionPaths();
     support.beginUpdate();
     support.postEdit(new SelectionEdit(selections, newSelections));
     support.postEdit(new CollapseEdit(path));
     support.endUpdate();
   }
 }
 public void expandPath(TreePath path) {
   boolean wasExpanded = isExpanded(path);
   TreePath[] selections = getSelectionPaths();
   super.expandPath(path);
   boolean isExpanded = isExpanded(path);
   if (isExpanded != wasExpanded) {
     TreePath[] newSelections = getSelectionPaths();
     support.beginUpdate();
     support.postEdit(new SelectionEdit(selections, newSelections));
     support.postEdit(new ExpandEdit(path));
     support.endUpdate();
   }
 }
 private void undoExpansion(TreePath path) {
   super.collapsePath(path);
 }
 private void undoCollapse(TreePath path) {
   super.expandPath(path);
 }
 private class CollapseEdit extends AbstractUndoableEdit {
   public CollapseEdit(TreePath path) {
     this.path = path;
   }
   public void undo() throws CannotUndoException {
     super.undo();
     UndoableTree2.this.undoCollapse(path);
   }
   public void redo() throws CannotRedoException {
     super.redo();
     UndoableTree2.this.undoExpansion(path);
   }
   public String getPresentationName() {
     return "node collapse";
   }
   private TreePath path;
 }
 private class ExpandEdit extends AbstractUndoableEdit {
   public ExpandEdit(TreePath path) {
     this.path = path;
   }
   public void undo() throws CannotUndoException {
     super.undo();
     UndoableTree2.this.undoExpansion(path);
   }
   public void redo() throws CannotRedoException {
     super.redo();
     UndoableTree2.this.undoCollapse(path);
   }
   public String getPresentationName() {
     return "node expansion";
   }
   private TreePath path;
 }
 private class SelectionEdit extends AbstractUndoableEdit {
   public SelectionEdit(TreePath[] oldSelections, TreePath[] newSelections) {
     this.oldSelections = oldSelections;
     this.newSelections = newSelections;
   }
   public void undo() throws CannotUndoException {
     super.undo();
     UndoableTree2.this.setSelectionPaths(oldSelections);
   }
   public void redo() throws CannotRedoException {
     super.redo();
     UndoableTree2.this.setSelectionPaths(newSelections);
   }
   public String getPresentationName() {
     return "selection change";
   }
   private TreePath[] oldSelections;
   private TreePath[] newSelections;
 }
 private UndoableEditSupport support = new UndoableEditSupport(this);

}

 </source>

Undo Example 5

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.BorderLayout; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.Hashtable; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JTextPane; import javax.swing.KeyStroke; import javax.swing.UIManager; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; import javax.swing.event.DocumentEvent; import javax.swing.event.DocumentListener; import javax.swing.event.EventListenerList; 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; import javax.swing.undo.UndoableEdit; public class UndoExample5 extends JFrame {

 public UndoExample5() {
   super("Undo/Redo Example 5");
   pane = new JTextPane();
   pane.setEditable(true); // Editable
   getContentPane().add(new JScrollPane(pane), BorderLayout.CENTER);
   // Add a menu bar
   menuBar = new JMenuBar();
   setJMenuBar(menuBar);
   // Populate the menu bar
   createMenuBar();
   // Create the undo manager and actions
   MonitorableUndoManager manager = new MonitorableUndoManager();
   pane.getDocument().addUndoableEditListener(manager);
   Action undoAction = new UndoAction(manager);
   Action redoAction = new RedoAction(manager);
   // Add the actions to buttons
   JPanel panel = new JPanel();
   final JButton undoButton = new JButton("Undo");
   final JButton redoButton = new JButton("Redo");
   undoButton.addActionListener(undoAction);
   redoButton.addActionListener(redoAction);
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   panel.add(undoButton);
   panel.add(redoButton);
   getContentPane().add(panel, BorderLayout.SOUTH);
   // Assign the actions to keys
   pane.registerKeyboardAction(undoAction, KeyStroke.getKeyStroke(
       KeyEvent.VK_Z, InputEvent.CTRL_MASK), JComponent.WHEN_FOCUSED);
   pane.registerKeyboardAction(redoAction, KeyStroke.getKeyStroke(
       KeyEvent.VK_Y, InputEvent.CTRL_MASK), JComponent.WHEN_FOCUSED);
   // Handle events from the MonitorableUndoManager
   manager.addChangeListener(new ChangeListener() {
     public void stateChanged(ChangeEvent evt) {
       MonitorableUndoManager m = (MonitorableUndoManager) evt
           .getSource();
       boolean canUndo = m.canUndo();
       boolean canRedo = m.canRedo();
       undoButton.setEnabled(canUndo);
       redoButton.setEnabled(canRedo);
       undoButton.setToolTipText(canUndo ? m.getUndoPresentationName()
           : null);
       redoButton.setToolTipText(canRedo ? m.getRedoPresentationName()
           : null);
     }
   });
 }
 public void createMenuBar() {
   // Remove the existing menu items
   int count = menuBar.getMenuCount();
   for (int i = 0; i < count; i++) {
     menuBar.remove(menuBar.getMenu(0));
   }
   // Build the new menu.
   Action[] actions = pane.getActions();
   Hashtable actionHash = new Hashtable();
   count = actions.length;
   for (int i = 0; i < count; i++) {
     actionHash.put(actions[i].getValue(Action.NAME), actions[i]);
   }
   // Add the font menu
   JMenu menu = MenuBuilder.buildMenu("Font", fontSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
   // Add the alignment menu
   menu = MenuBuilder.buildMenu("Align", alignSpec, actionHash);
   if (menu != null) {
     menuBar.add(menu);
   }
 }
 // The Undo action
 public class UndoAction extends AbstractAction {
   public UndoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.undo();
     } catch (CannotUndoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 // The Redo action
 public class RedoAction extends AbstractAction {
   public RedoAction(UndoManager manager) {
     this.manager = manager;
   }
   public void actionPerformed(ActionEvent evt) {
     try {
       manager.redo();
     } catch (CannotRedoException e) {
       Toolkit.getDefaultToolkit().beep();
     }
   }
   private UndoManager manager;
 }
 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   JFrame f = new UndoExample5();
   f.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent evt) {
       System.exit(0);
     }
   });
   f.setSize(250, 300);
   f.setVisible(true);
   // Create and show a frame monitoring undoable edits
   JFrame undoMonitor = new JFrame("Undo Monitor");
   final JTextArea textArea = new JTextArea();
   textArea.setEditable(false);
   undoMonitor.getContentPane().add(new JScrollPane(textArea));
   undoMonitor.setBounds(f.getLocation().x + f.getSize().width, f
       .getLocation().y, 400, 200);
   undoMonitor.setVisible(true);
   pane.getDocument().addUndoableEditListener(new UndoableEditListener() {
     public void undoableEditHappened(UndoableEditEvent evt) {
       UndoableEdit edit = evt.getEdit();
       textArea.append(edit.getPresentationName() + "("
           + edit.toString() + ")\n");
     }
   });
   // Create and show a frame monitoring document edits
   JFrame editMonitor = new JFrame("Edit Monitor");
   final JTextArea textArea2 = new JTextArea();
   textArea2.setEditable(false);
   editMonitor.getContentPane().add(new JScrollPane(textArea2));
   editMonitor.setBounds(undoMonitor.getLocation().x, undoMonitor
       .getLocation().y
       + undoMonitor.getSize().height, 400, 200);
   editMonitor.setVisible(true);
   pane.getDocument().addDocumentListener(new DocumentListener() {
     public void changedUpdate(DocumentEvent evt) {
       textArea2.append("Attribute change\n");
     }
     public void insertUpdate(DocumentEvent evt) {
       textArea2.append("Text insertion\n");
     }
     public void removeUpdate(DocumentEvent evt) {
       textArea2.append("Text removal\n");
     }
   });
 }
 private static JTextPane pane;
 private static JMenuBar menuBar;
 private static MenuSpec[] sizeSpec = new MenuSpec[] {
     new MenuSpec("Size 8", "font-size-8"),
     new MenuSpec("Size 10", "font-size-10"),
     new MenuSpec("Size 12", "font-size-12"),
     new MenuSpec("Size 14", "font-size-14"),
     new MenuSpec("Size 16", "font-size-16"),
     new MenuSpec("Size 18", "font-size-18"),
     new MenuSpec("Size 24", "font-size-24"),
     new MenuSpec("Size 36", "font-size-36"),
     new MenuSpec("Size 48", "font-size-48") };
 private static MenuSpec[] familySpec = new MenuSpec[] {
     new MenuSpec("Sans Serif", "font-family-SansSerif"),
     new MenuSpec("Monospaced", "font-family-Monospaced"),
     new MenuSpec("Serif", "font-family-Serif") };
 private static MenuSpec[] styleSpec = new MenuSpec[] {
     new MenuSpec("Bold", "font-bold"),
     new MenuSpec("Italics", "font-italic"),
     new MenuSpec("Underline", "font-underline") };
 // Menu definitions for fonts
 private static MenuSpec[] fontSpec = new MenuSpec[] {
     new MenuSpec("Size", sizeSpec), new MenuSpec("Family", familySpec),
     new MenuSpec("Style", styleSpec) };
 // Alignment
 private static MenuSpec[] alignSpec = new MenuSpec[] {
     new MenuSpec("Left", "left-justify"),
     new MenuSpec("Center", "center-justify"),
     new MenuSpec("Right", "right-justify") };

} class MonitorableUndoManager extends UndoManager {

 // List of listeners for events from this object
 protected EventListenerList listenerList = new EventListenerList();
 // A ChangeEvent dedicated to a single MonitorableUndoManager
 protected ChangeEvent changeEvent;
 // Super class overrides
 public synchronized void setLimit(int l) {
   super.setLimit(l);
   fireChangeEvent();
 }
 public synchronized void discardAllEdits() {
   super.discardAllEdits();
   fireChangeEvent();
 }
 public synchronized void undo() throws CannotUndoException {
   super.undo();
   fireChangeEvent();
 }
 public synchronized void redo() throws CannotRedoException {
   super.redo();
   fireChangeEvent();
 }
 public synchronized boolean addEdit(UndoableEdit anEdit) {
   boolean retval = super.addEdit(anEdit);
   fireChangeEvent();
   return retval;
 }
 // Support for ChangeListeners
 public void addChangeListener(ChangeListener l) {
   listenerList.add(ChangeListener.class, l);
 }
 public void removeChangeListener(ChangeListener l) {
   listenerList.remove(ChangeListener.class, l);
 }
 protected void fireChangeEvent() {
   Object[] listeners = listenerList.getListenerList();
   for (int i = listeners.length - 2; i >= 0; i -= 2) {
     if (listeners[i] == ChangeListener.class) {
       if (changeEvent == null) {
         changeEvent = new ChangeEvent(this);
       }
       ((ChangeListener) listeners[i + 1]).stateChanged(changeEvent);
     }
   }
 }

} class MenuSpec {

 public MenuSpec(String name, MenuSpec[] subMenus) {
   this.name = name;
   this.subMenus = subMenus;
 }
 public MenuSpec(String name, String actionName) {
   this.name = name;
   this.actionName = actionName;
 }
 public MenuSpec(String name, Action action) {
   this.name = name;
   this.action = action;
 }
 public boolean isSubMenu() {
   return subMenus != null;
 }
 public boolean isAction() {
   return action != null;
 }
 public String getName() {
   return name;
 }
 public MenuSpec[] getSubMenus() {
   return subMenus;
 }
 public String getActionName() {
   return actionName;
 }
 public Action getAction() {
   return action;
 }
 private String name;
 private String actionName;
 private Action action;
 private MenuSpec[] subMenus;

} class MenuBuilder {

 public static JMenu buildMenu(String name, MenuSpec[] menuSpecs,
     Hashtable actions) {
   int count = menuSpecs.length;
   JMenu menu = new JMenu(name);
   for (int i = 0; i < count; i++) {
     MenuSpec spec = menuSpecs[i];
     if (spec.isSubMenu()) {
       // Recurse to handle a sub menu
       JMenu subMenu = buildMenu(spec.getName(), spec.getSubMenus(),
           actions);
       if (subMenu != null) {
         menu.add(subMenu);
       }
     } else if (spec.isAction()) {
       // It"s an Action - add it directly to the menu
       menu.add(spec.getAction());
     } else {
       // It"s an action name - add it if possible
       String actionName = spec.getActionName();
       Action targetAction = (Action) actions.get(actionName);
       // Create the menu item
       JMenuItem menuItem = menu.add(spec.getName());
       if (targetAction != null) {
         // The editor kit knows the action
         menuItem.addActionListener(targetAction);
       } else {
         // Action not known - disable the menu item
         menuItem.setEnabled(false);
       }
     }
   }
   // Return null if nothing was added to the menu.
   if (menu.getMenuComponentCount() == 0) {
     menu = null;
   }
   return menu;
 }

}

 </source>

Undo Example 6

   <source lang="java">

/* Core SWING Advanced Programming By Kim Topley ISBN: 0 13 083292 8 Publisher: Prentice Hall

/

import java.awt.Dimension; import java.awt.Insets; import java.awt.Point; import java.awt.Rectangle; import java.awt.dnd.Autoscroll; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.io.File; import java.io.FileNotFoundException; import java.util.ArrayList; import java.util.Arrays; import java.util.ruparator; import javax.swing.JFrame; import javax.swing.JScrollBar; import javax.swing.JScrollPane; import javax.swing.JTree; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.event.TreeExpansionEvent; import javax.swing.event.TreeExpansionListener; import javax.swing.event.TreeSelectionEvent; import javax.swing.event.TreeSelectionListener; import javax.swing.tree.DefaultMutableTreeNode; import javax.swing.tree.DefaultTreeModel; import javax.swing.tree.TreeModel; import javax.swing.tree.TreePath; public class FileTreeTest {

 public static void main(String[] args) {
   try {
       UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
   } catch (Exception evt) {}
 
   try {
     JFrame f = new JFrame("File Tree Test");
     final FileTree ft = new FileTree("D:\\");
     ft.addTreeSelectionListener(new TreeSelectionListener() {
       public void valueChanged(TreeSelectionEvent evt) {
         TreePath path = evt.getPath();
         String name = ft.getPathName(path);
         System.out.println("File " + name + " has been "
             + (evt.isAddedPath() ? "selected" : "deselected"));
       }
     });
     f.getContentPane().add(new JScrollPane(ft));
     f.setSize(300, 300);
     f.addWindowListener(new WindowAdapter() {
       public void windowClosing(WindowEvent evt) {
         System.exit(0);
       }
     });
     f.setVisible(true);
   } catch (FileNotFoundException e) {
     System.out.println("File " + args[0] + " not found");
   }
 }

} class FileTree extends JTree implements Autoscroll {

 public static final Insets defaultScrollInsets = new Insets(8, 8, 8, 8);
 protected Insets scrollInsets = defaultScrollInsets;
 public FileTree(String path) throws FileNotFoundException,
     SecurityException {
   super((TreeModel) null); // Create the JTree itself
   // Use horizontal and vertical lines
   putClientProperty("JTree.lineStyle", "Angled");
   // Create the first node
   FileTreeNode rootNode = new FileTreeNode(null, path);
   // Populate the root node with its subdirectories
   boolean addedNodes = rootNode.populateDirectories(true);
   setModel(new DefaultTreeModel(rootNode));
   // Listen for Tree Selection Events
   addTreeExpansionListener(new TreeExpansionHandler());
 }
 // Returns the full pathname for a path, or null if not a known path
 public String getPathName(TreePath path) {
   Object o = path.getLastPathComponent();
   if (o instanceof FileTreeNode) {
     return ((FileTreeNode) o).fullName;
   }
   return null;
 }
 // Adds a new node to the tree after construction.
 // Returns the inserted node, or null if the parent
 // directory has not been expanded.
 public FileTreeNode addNode(FileTreeNode parent, String name) {
   int index = parent.addNode(name);
   if (index != -1) {
     ((DefaultTreeModel) getModel()).nodesWereInserted(parent,
         new int[] { index });
     return (FileTreeNode) parent.getChildAt(index);
   }
   // No node was created
   return null;
 }
 // Autoscrolling support
 public void setScrollInsets(Insets insets) {
   this.scrollInsets = insets;
 }
 public Insets getScrollInsets() {
   return scrollInsets;
 }
 // Implementation of Autoscroll interface
 public Insets getAutoscrollInsets() {
   Rectangle r = getVisibleRect();
   Dimension size = getSize();
   Insets i = new Insets(r.y + scrollInsets.top, r.x + scrollInsets.left,
       size.height - r.y - r.height + scrollInsets.bottom, size.width
           - r.x - r.width + scrollInsets.right);
   return i;
 }
 public void autoscroll(Point location) {
   JScrollPane scroller = (JScrollPane) SwingUtilities.getAncestorOfClass(
       JScrollPane.class, this);
   if (scroller != null) {
     JScrollBar hBar = scroller.getHorizontalScrollBar();
     JScrollBar vBar = scroller.getVerticalScrollBar();
     Rectangle r = getVisibleRect();
     if (location.x <= r.x + scrollInsets.left) {
       // Need to scroll left
       hBar.setValue(hBar.getValue() - hBar.getUnitIncrement(-1));
     }
     if (location.y <= r.y + scrollInsets.top) {
       // Need to scroll up
       vBar.setValue(vBar.getValue() - vBar.getUnitIncrement(-1));
     }
     if (location.x >= r.x + r.width - scrollInsets.right) {
       // Need to scroll right
       hBar.setValue(hBar.getValue() + hBar.getUnitIncrement(1));
     }
     if (location.y >= r.y + r.height - scrollInsets.bottom) {
       // Need to scroll down
       vBar.setValue(vBar.getValue() + vBar.getUnitIncrement(1));
     }
   }
 }
 // Inner class that represents a node in this file system tree
 public static class FileTreeNode extends DefaultMutableTreeNode {
   public FileTreeNode(String parent, String name)
       throws SecurityException, FileNotFoundException {
     this.name = name;
     // See if this node exists and whether it is a directory
     fullName = parent == null ? name : parent + File.separator + name;
     File f = new File(fullName);
     if (f.exists() == false) {
       throw new FileNotFoundException("File " + fullName
           + " does not exist");
     }
     isDir = f.isDirectory();
     // Hack for Windows which doesn"t consider a drive to be a
     // directory!
     if (isDir == false && f.isFile() == false) {
       isDir = true;
     }
   }
   // Override isLeaf to check whether this is a directory
   public boolean isLeaf() {
     return !isDir;
   }
   // Override getAllowsChildren to check whether this is a directory
   public boolean getAllowsChildren() {
     return isDir;
   }
   // Return whether this is a directory
   public boolean isDir() {
     return isDir;
   }
   // Get full path
   public String getFullName() {
     return fullName;
   }
   // For display purposes, we return our own name
   public String toString() {
     return name;
   }
   // If we are a directory, scan our contents and populate
   // with children. In addition, populate those children
   // if the "descend" flag is true. We only descend once,
   // to avoid recursing the whole subtree.
   // Returns true if some nodes were added
   boolean populateDirectories(boolean descend) {
     boolean addedNodes = false;
     // Do this only once
     if (populated == false) {
       File f;
       try {
         f = new File(fullName);
       } catch (SecurityException e) {
         populated = true;
         return false;
       }
       if (interim == true) {
         // We have had a quick look here before:
         // remove the dummy node that we added last time
         removeAllChildren();
         interim = false;
       }
       String[] names = f.list(); // Get list of contents
       // Process the contents
       ArrayList list = new ArrayList();
       for (int i = 0; i < names.length; i++) {
         String name = names[i];
         File d = new File(fullName, name);
         try {
           FileTreeNode node = new FileTreeNode(fullName, name);
           list.add(node);
           if (descend && d.isDirectory()) {
             node.populateDirectories(false);
           }
           addedNodes = true;
           if (descend == false) {
             // Only add one node if not descending
             break;
           }
         } catch (Throwable t) {
           // Ignore phantoms or access problems
         }
       }
       if (addedNodes == true) {
         // Now sort the list of contained files and directories
         Object[] nodes = list.toArray();
         Arrays.sort(nodes, new Comparator() {
           public boolean equals(Object o) {
             return false;
           }
           public int compare(Object o1, Object o2) {
             FileTreeNode node1 = (FileTreeNode) o1;
             FileTreeNode node2 = (FileTreeNode) o2;
             // Directories come first
             if (node1.isDir != node2.isDir) {
               return node1.isDir ? -1 : +1;
             }
             // Both directories or both files -
             // compare based on pathname
             return node1.fullName.rupareTo(node2.fullName);
           }
         });
         // Add sorted items as children of this node
         for (int j = 0; j < nodes.length; j++) {
           this.add((FileTreeNode) nodes[j]);
         }
       }
       // If we were scanning to get all subdirectories,
       // or if we found no content, there is no
       // reason to look at this directory again, so
       // set populated to true. Otherwise, we set interim
       // so that we look again in the future if we need to
       if (descend == true || addedNodes == false) {
         populated = true;
       } else {
         // Just set interim state
         interim = true;
       }
     }
     return addedNodes;
   }
   // Adding a new file or directory after
   // constructing the FileTree. Returns
   // the index of the inserted node.
   public int addNode(String name) {
     // If not populated yet, do nothing
     if (populated == true) {
       // Do not add a new node if
       // the required node is already there
       int childCount = getChildCount();
       for (int i = 0; i < childCount; i++) {
         FileTreeNode node = (FileTreeNode) getChildAt(i);
         if (node.name.equals(name)) {
           // Already exists - ensure
           // we repopulate
           if (node.isDir()) {
             node.interim = true;
             node.populated = false;
           }
           return -1;
         }
       }
       // Add a new node
       try {
         FileTreeNode node = new FileTreeNode(fullName, name);
         add(node);
         return childCount;
       } catch (Exception e) {
       }
     }
     return -1;
   }
   protected String name; // Name of this component
   protected String fullName; // Full pathname
   protected boolean populated;// true if we have been populated
   protected boolean interim; // true if we are in interim state
   protected boolean isDir; // true if this is a directory
 }
 // Inner class that handles Tree Expansion Events
 protected class TreeExpansionHandler implements TreeExpansionListener {
   public void treeExpanded(TreeExpansionEvent evt) {
     TreePath path = evt.getPath(); // The expanded path
     JTree tree = (JTree) evt.getSource(); // The tree
     // Get the last component of the path and
     // arrange to have it fully populated.
     FileTreeNode node = (FileTreeNode) path.getLastPathComponent();
     if (node.populateDirectories(true)) {
       ((DefaultTreeModel) tree.getModel()).nodeStructureChanged(node);
     }
   }
   public void treeCollapsed(TreeExpansionEvent evt) {
     // Nothing to do
   }
 }

}

 </source>

Undo Example 7

   <source lang="java">

/* Definitive Guide to Swing for Java 2, Second Edition By John Zukowski ISBN: 1-893115-78-X Publisher: APress

/

import java.awt.BorderLayout; import java.awt.ruponent; import java.awt.Container; import java.awt.event.ActionEvent; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JToolBar; import javax.swing.undo.CannotRedoException; import javax.swing.undo.CannotUndoException; import javax.swing.undo.UndoManager; public class UndoSample {

 public static void main(String args[]) {
   JFrame frame = new JFrame("Undo Sample");
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   JTextArea textArea = new JTextArea();
   JScrollPane scrollPane = new JScrollPane(textArea);
   UndoManager manager = new UndoManager();
   textArea.getDocument().addUndoableEditListener(manager);
   JToolBar toolbar = new JToolBar();
   toolbar.add(UndoManagerHelper.getUndoAction(manager));
   toolbar.add(UndoManagerHelper.getRedoAction(manager));
   Container content = frame.getContentPane();
   content.add(toolbar, BorderLayout.NORTH);
   content.add(scrollPane, BorderLayout.CENTER);
   frame.setSize(300, 150);
   frame.setVisible(true);
 }

} class UndoManagerHelper {

 public static Action getUndoAction(UndoManager manager, String label) {
   return new UndoAction(manager, label);
 }
 public static Action getUndoAction(UndoManager manager) {
   return new UndoAction(manager, "Undo");
 }
 public static Action getRedoAction(UndoManager manager, String label) {
   return new RedoAction(manager, label);
 }
 public static Action getRedoAction(UndoManager manager) {
   return new RedoAction(manager, "Redo");
 }
 private abstract static class UndoRedoAction extends AbstractAction {
   UndoManager undoManager = new UndoManager();
   String errorMessage = "Cannot undo";
   String errorTitle = "Undo Problem";
   protected UndoRedoAction(UndoManager manager, String name) {
     super(name);
     undoManager = manager;
   }
   public void setErrorMessage(String newValue) {
     errorMessage = newValue;
   }
   public void setErrorTitle(String newValue) {
     errorTitle = newValue;
   }
   protected void showMessage(Object source) {
     if (source instanceof Component) {
       JOptionPane.showMessageDialog((Component) source, errorMessage,
           errorTitle, JOptionPane.WARNING_MESSAGE);
     } else {
       System.err.println(errorMessage);
     }
   }
 }
 public static class UndoAction extends UndoRedoAction {
   public UndoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot undo");
     setErrorTitle("Undo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.undo();
     } catch (CannotUndoException cannotUndoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }
 public static class RedoAction extends UndoRedoAction {
   String errorMessage = "Cannot redo";
   String errorTitle = "Redo Problem";
   public RedoAction(UndoManager manager, String name) {
     super(manager, name);
     setErrorMessage("Cannot redo");
     setErrorTitle("Redo Problem");
   }
   public void actionPerformed(ActionEvent actionEvent) {
     try {
       undoManager.redo();
     } catch (CannotRedoException cannotRedoException) {
       showMessage(actionEvent.getSource());
     }
   }
 }

}

 </source>

Undo manager

   <source lang="java">

import java.awt.BorderLayout; import java.awt.Color; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.Point; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.util.Enumeration; import java.util.Vector; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.event.UndoableEditEvent; import javax.swing.undo.AbstractUndoableEdit; import javax.swing.undo.CannotRedoException; import javax.swing.undo.UndoManager; public class UndoManagerDemo extends JFrame {

 protected Vector pointVector = new Vector();
 protected PaintCanvas canvas = new PaintCanvas(pointVector);
 protected UndoManager undoManager = new UndoManager();
 protected JButton undoButton = new JButton("Undo");
 protected JButton redoButton = new JButton("Redo");
 public UndoManagerDemo() {
   super("Undo/Redo Demo");
   undoButton.setEnabled(false);
   redoButton.setEnabled(false);
   JPanel buttonPanel = new JPanel(new GridLayout());
   buttonPanel.add(undoButton);
   buttonPanel.add(redoButton);
   getContentPane().add(buttonPanel, BorderLayout.NORTH);
   getContentPane().add(canvas, BorderLayout.CENTER);
   canvas.addMouseListener(new MouseAdapter() {
     public void mousePressed(MouseEvent e) {
       Point point = new Point(e.getX(), e.getY());
       pointVector.addElement(point);
       undoManager.undoableEditHappened(new UndoableEditEvent(
           canvas, new UndoablePaintSquare(point, pointVector)));
       undoButton.setText(undoManager.getUndoPresentationName());
       redoButton.setText(undoManager.getRedoPresentationName());
       undoButton.setEnabled(undoManager.canUndo());
       redoButton.setEnabled(undoManager.canRedo());
       canvas.repaint();
     }
   });
   undoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       try {
         undoManager.undo();
       } catch (CannotRedoException cre) {
         cre.printStackTrace();
       }
       canvas.repaint();
       undoButton.setEnabled(undoManager.canUndo());
       redoButton.setEnabled(undoManager.canRedo());
     }
   });
   redoButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       try {
         undoManager.redo();
       } catch (CannotRedoException cre) {
         cre.printStackTrace();
       }
       canvas.repaint();
       undoButton.setEnabled(undoManager.canUndo());
       redoButton.setEnabled(undoManager.canRedo());
     }
   });
   setSize(400, 300);
   setVisible(true);
 }
 public static void main(String argv[]) {
   new UndoManagerDemo();
 }
 class PaintCanvas extends JPanel {
   private Vector points;
   protected int width = 50;
   protected int height = 50;
   public PaintCanvas(Vector v) {
     super();
     points = v;
     setOpaque(true);
     setBackground(Color.white);
   }
   public void paintComponent(Graphics g) {
     super.paintComponent(g);
     g.setColor(Color.black);
     
     for(int i=0;i<points.size();i++){
       Point point = (Point) points.get(i);
       g.drawRect(point.x, point.y, width, height);
     }
   }
 }
 class UndoablePaintSquare extends AbstractUndoableEdit {
   protected Vector points;
   protected Point point;
   public UndoablePaintSquare(Point p, Vector v) {
     points = v;
     point = p;
   }
   public String getPresentationName() {
     return "Square Addition";
   }
   public void undo() {
     super.undo();
     points.remove(point);
   }
   public void redo() {
     super.redo();
     points.add(point);
   }
 }

}

 </source>

Undo redo textarea

   <source lang="java">

import java.awt.BorderLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; 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.UndoManager; public class UndoRedoTextArea extends JFrame {

 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();
     }
   });
   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();
 }

}

 </source>

Java/Swing JFC/Undo Redo

Содержание

Adding Undo and Redo to a Text Component

Add Undo and Redo to a text component

Add undo support to the StyleFrame example

An example that shows lots of little UndoManager details

A sample app showing the use of UndoableToggleEdit and CompoundEdit

Bind the undo action to ctl-Z

Create an undo action and add it to the text component

Create a redo action and add it to the text component (JTextComponent)

Creating TextArea with Undo, Redo Capabilities

Listen for undo and redo events

Simple GUI demo of UndoManager and friends

The use of StateEdit(able)

The use of UndoableToggleEdit

The use of UndoManager

Undoable Drawing Panel 2

Undo Drawing

Undo Example 1

Undo Example 2

Undo Example 3

Undo Example 4

Undo Example 5

Undo Example 6

Undo Example 7

Undo manager

Undo redo textarea

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