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		<id>http://www.jexp.ru/index.php?action=history&amp;feed=atom&amp;title=Java_by_API%2Fjavax.swing.undo%2FUndoableEditSupport</id>
		<title>Java by API/javax.swing.undo/UndoableEditSupport - История изменений</title>
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		<updated>2026-04-27T15:57:41Z</updated>
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	<entry>
		<id>http://www.jexp.ru/index.php?title=Java_by_API/javax.swing.undo/UndoableEditSupport&amp;diff=1901&amp;oldid=prev</id>
		<title> в 17:43, 31 мая 2010</title>
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				<updated>2010-05-31T17:43:48Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
				&lt;tr style=&quot;vertical-align: top;&quot; lang=&quot;ru&quot;&gt;
				&lt;td colspan=&quot;1&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;← Предыдущая&lt;/td&gt;
				&lt;td colspan=&quot;1&quot; style=&quot;background-color: white; color:black; text-align: center;&quot;&gt;Версия 17:43, 31 мая 2010&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; style=&quot;text-align: center;&quot; lang=&quot;ru&quot;&gt;&lt;div class=&quot;mw-diff-empty&quot;&gt;(нет различий)&lt;/div&gt;
&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;</summary>
			</entry>

	<entry>
		<id>http://www.jexp.ru/index.php?title=Java_by_API/javax.swing.undo/UndoableEditSupport&amp;diff=1902&amp;oldid=prev</id>
		<title>Admin: 1 версия</title>
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				<updated>2010-05-31T14:38:21Z</updated>
		
		<summary type="html">&lt;p&gt;1 версия&lt;/p&gt;
&lt;p&gt;&lt;b&gt;Новая страница&lt;/b&gt;&lt;/p&gt;&lt;div&gt;== UndoableEditSupport: addUndoableEditListener(UndoableEditListener l) ==&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
   &lt;br /&gt;
  &amp;lt;!-- start source code --&amp;gt;&lt;br /&gt;
   &lt;br /&gt;
    &amp;lt;source lang=&amp;quot;java&amp;quot;&amp;gt;&lt;br /&gt;
import java.awt.BorderLayout;&lt;br /&gt;
import java.awt.ruponent;&lt;br /&gt;
import java.awt.Container;&lt;br /&gt;
import java.awt.Graphics;&lt;br /&gt;
import java.awt.Polygon;&lt;br /&gt;
import java.awt.event.ActionEvent;&lt;br /&gt;
import java.awt.event.MouseAdapter;&lt;br /&gt;
import java.awt.event.MouseEvent;&lt;br /&gt;
import java.awt.event.MouseListener;&lt;br /&gt;
import javax.swing.AbstractAction;&lt;br /&gt;
import javax.swing.Action;&lt;br /&gt;
import javax.swing.JButton;&lt;br /&gt;
import javax.swing.JFrame;&lt;br /&gt;
import javax.swing.JOptionPane;&lt;br /&gt;
import javax.swing.JPanel;&lt;br /&gt;
import javax.swing.JToolBar;&lt;br /&gt;
import javax.swing.UIManager;&lt;br /&gt;
import javax.swing.event.UndoableEditListener;&lt;br /&gt;
import javax.swing.undo.AbstractUndoableEdit;&lt;br /&gt;
import javax.swing.undo.CannotRedoException;&lt;br /&gt;
import javax.swing.undo.CannotUndoException;&lt;br /&gt;
import javax.swing.undo.UndoManager;&lt;br /&gt;
import javax.swing.undo.UndoableEditSupport;&lt;br /&gt;
public class UndoDrawing {&lt;br /&gt;
  public static void main(String args[]) {&lt;br /&gt;
    JFrame frame = new JFrame(&amp;quot;Drawing Sample&amp;quot;);&lt;br /&gt;
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);&lt;br /&gt;
    UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();&lt;br /&gt;
    UndoManager manager = new UndoManager();&lt;br /&gt;
    drawingPanel.addUndoableEditListener(manager);&lt;br /&gt;
    JToolBar toolbar = new JToolBar();&lt;br /&gt;
    JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));&lt;br /&gt;
    toolbar.add(undoButton);&lt;br /&gt;
    JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));&lt;br /&gt;
    toolbar.add(redoButton);&lt;br /&gt;
    Container content = frame.getContentPane();&lt;br /&gt;
    content.add(toolbar, BorderLayout.NORTH);&lt;br /&gt;
    content.add(drawingPanel, BorderLayout.CENTER);&lt;br /&gt;
    frame.setSize(300, 150);&lt;br /&gt;
    frame.setVisible(true);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawEdit extends AbstractUndoableEdit {&lt;br /&gt;
  UndoableDrawingPanel panel;&lt;br /&gt;
  Polygon polygon, savedPolygon;&lt;br /&gt;
  public UndoableDrawEdit(UndoableDrawingPanel panel) {&lt;br /&gt;
    this.panel = panel;&lt;br /&gt;
    polygon = panel.getPolygon();&lt;br /&gt;
  }&lt;br /&gt;
  public String getPresentationName() {&lt;br /&gt;
    return &amp;quot;Polygon of size &amp;quot; + polygon.npoints;&lt;br /&gt;
  }&lt;br /&gt;
  public void redo() throws CannotRedoException {&lt;br /&gt;
    super.redo();&lt;br /&gt;
    if (savedPolygon == null) {&lt;br /&gt;
      // Should never get here, as super() doesn&amp;quot;t permit redoing&lt;br /&gt;
      throw new CannotRedoException();&lt;br /&gt;
    } else {&lt;br /&gt;
      panel.setPolygon(savedPolygon);&lt;br /&gt;
      savedPolygon = null;&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public void undo() throws CannotUndoException {&lt;br /&gt;
    super.undo();&lt;br /&gt;
    savedPolygon = panel.getPolygon();&lt;br /&gt;
    panel.setPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawingPanel extends JPanel {&lt;br /&gt;
  UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);&lt;br /&gt;
  Polygon polygon = new Polygon();&lt;br /&gt;
  public UndoableDrawingPanel() {&lt;br /&gt;
    MouseListener mouseListener = new MouseAdapter() {&lt;br /&gt;
      public void mouseReleased(MouseEvent mouseEvent) {&lt;br /&gt;
        undoableEditSupport.postEdit(new UndoableDrawEdit(UndoableDrawingPanel.this));&lt;br /&gt;
        polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());&lt;br /&gt;
        repaint();&lt;br /&gt;
      }&lt;br /&gt;
    };&lt;br /&gt;
    addMouseListener(mouseListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void addUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.addUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.removeUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void setPolygon(Polygon newValue) {&lt;br /&gt;
    polygon = newValue;&lt;br /&gt;
    repaint();&lt;br /&gt;
  }&lt;br /&gt;
  public Polygon getPolygon() {&lt;br /&gt;
    Polygon returnValue;&lt;br /&gt;
    if (polygon.npoints == 0) {&lt;br /&gt;
      returnValue = new Polygon();&lt;br /&gt;
    } else {&lt;br /&gt;
      returnValue = new Polygon(polygon.xpoints, polygon.ypoints, polygon.npoints);&lt;br /&gt;
    }&lt;br /&gt;
    return returnValue;&lt;br /&gt;
  }&lt;br /&gt;
  protected void paintComponent(Graphics g) {&lt;br /&gt;
    super.paintComponent(g);&lt;br /&gt;
    g.drawPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoManagerHelper {&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new UndoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager) {&lt;br /&gt;
    return new UndoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.undoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new RedoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager) {&lt;br /&gt;
    return new RedoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.redoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  private abstract static class UndoRedoAction extends AbstractAction {&lt;br /&gt;
    UndoManager undoManager = new UndoManager();&lt;br /&gt;
    String errorMessage = &amp;quot;Cannot undo&amp;quot;;&lt;br /&gt;
    String errorTitle = &amp;quot;Undo Problem&amp;quot;;&lt;br /&gt;
    protected UndoRedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(name);&lt;br /&gt;
      undoManager = manager;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorMessage(String newValue) {&lt;br /&gt;
      errorMessage = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorTitle(String newValue) {&lt;br /&gt;
      errorTitle = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    protected void showMessage(Object source) {&lt;br /&gt;
      if (source instanceof Component) {&lt;br /&gt;
        JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,&lt;br /&gt;
            JOptionPane.WARNING_MESSAGE);&lt;br /&gt;
      } else {&lt;br /&gt;
        System.err.println(errorMessage);&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class UndoAction extends UndoRedoAction {&lt;br /&gt;
    public UndoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot undo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Undo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.undo();&lt;br /&gt;
      } catch (CannotUndoException cannotUndoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class RedoAction extends UndoRedoAction {&lt;br /&gt;
    public RedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot redo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Redo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.redo();&lt;br /&gt;
      } catch (CannotRedoException cannotRedoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
           &lt;br /&gt;
       &amp;lt;/source&amp;gt;&lt;br /&gt;
    &lt;br /&gt;
   &lt;br /&gt;
  &amp;lt;!-- end source code --&amp;gt;&lt;br /&gt;
   &lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
== UndoableEditSupport: postEdit(UndoableEdit e) ==&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
   &lt;br /&gt;
  &amp;lt;!-- start source code --&amp;gt;&lt;br /&gt;
   &lt;br /&gt;
    &amp;lt;source lang=&amp;quot;java&amp;quot;&amp;gt;&lt;br /&gt;
import java.awt.BorderLayout;&lt;br /&gt;
import java.awt.ruponent;&lt;br /&gt;
import java.awt.Container;&lt;br /&gt;
import java.awt.Graphics;&lt;br /&gt;
import java.awt.Polygon;&lt;br /&gt;
import java.awt.event.ActionEvent;&lt;br /&gt;
import java.awt.event.MouseAdapter;&lt;br /&gt;
import java.awt.event.MouseEvent;&lt;br /&gt;
import java.awt.event.MouseListener;&lt;br /&gt;
import javax.swing.AbstractAction;&lt;br /&gt;
import javax.swing.Action;&lt;br /&gt;
import javax.swing.JButton;&lt;br /&gt;
import javax.swing.JFrame;&lt;br /&gt;
import javax.swing.JOptionPane;&lt;br /&gt;
import javax.swing.JPanel;&lt;br /&gt;
import javax.swing.JToolBar;&lt;br /&gt;
import javax.swing.UIManager;&lt;br /&gt;
import javax.swing.event.UndoableEditListener;&lt;br /&gt;
import javax.swing.undo.AbstractUndoableEdit;&lt;br /&gt;
import javax.swing.undo.CannotRedoException;&lt;br /&gt;
import javax.swing.undo.CannotUndoException;&lt;br /&gt;
import javax.swing.undo.UndoManager;&lt;br /&gt;
import javax.swing.undo.UndoableEditSupport;&lt;br /&gt;
public class UndoDrawing {&lt;br /&gt;
  public static void main(String args[]) {&lt;br /&gt;
    JFrame frame = new JFrame(&amp;quot;Drawing Sample&amp;quot;);&lt;br /&gt;
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);&lt;br /&gt;
    UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();&lt;br /&gt;
    UndoManager manager = new UndoManager();&lt;br /&gt;
    drawingPanel.addUndoableEditListener(manager);&lt;br /&gt;
    JToolBar toolbar = new JToolBar();&lt;br /&gt;
    JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));&lt;br /&gt;
    toolbar.add(undoButton);&lt;br /&gt;
    JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));&lt;br /&gt;
    toolbar.add(redoButton);&lt;br /&gt;
    Container content = frame.getContentPane();&lt;br /&gt;
    content.add(toolbar, BorderLayout.NORTH);&lt;br /&gt;
    content.add(drawingPanel, BorderLayout.CENTER);&lt;br /&gt;
    frame.setSize(300, 150);&lt;br /&gt;
    frame.setVisible(true);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawEdit extends AbstractUndoableEdit {&lt;br /&gt;
  UndoableDrawingPanel panel;&lt;br /&gt;
  Polygon polygon, savedPolygon;&lt;br /&gt;
  public UndoableDrawEdit(UndoableDrawingPanel panel) {&lt;br /&gt;
    this.panel = panel;&lt;br /&gt;
    polygon = panel.getPolygon();&lt;br /&gt;
  }&lt;br /&gt;
  public String getPresentationName() {&lt;br /&gt;
    return &amp;quot;Polygon of size &amp;quot; + polygon.npoints;&lt;br /&gt;
  }&lt;br /&gt;
  public void redo() throws CannotRedoException {&lt;br /&gt;
    super.redo();&lt;br /&gt;
    if (savedPolygon == null) {&lt;br /&gt;
      // Should never get here, as super() doesn&amp;quot;t permit redoing&lt;br /&gt;
      throw new CannotRedoException();&lt;br /&gt;
    } else {&lt;br /&gt;
      panel.setPolygon(savedPolygon);&lt;br /&gt;
      savedPolygon = null;&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public void undo() throws CannotUndoException {&lt;br /&gt;
    super.undo();&lt;br /&gt;
    savedPolygon = panel.getPolygon();&lt;br /&gt;
    panel.setPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawingPanel extends JPanel {&lt;br /&gt;
  UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);&lt;br /&gt;
  Polygon polygon = new Polygon();&lt;br /&gt;
  public UndoableDrawingPanel() {&lt;br /&gt;
    MouseListener mouseListener = new MouseAdapter() {&lt;br /&gt;
      public void mouseReleased(MouseEvent mouseEvent) {&lt;br /&gt;
        undoableEditSupport.postEdit(new UndoableDrawEdit(UndoableDrawingPanel.this));&lt;br /&gt;
        polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());&lt;br /&gt;
        repaint();&lt;br /&gt;
      }&lt;br /&gt;
    };&lt;br /&gt;
    addMouseListener(mouseListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void addUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.addUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.removeUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void setPolygon(Polygon newValue) {&lt;br /&gt;
    polygon = newValue;&lt;br /&gt;
    repaint();&lt;br /&gt;
  }&lt;br /&gt;
  public Polygon getPolygon() {&lt;br /&gt;
    Polygon returnValue;&lt;br /&gt;
    if (polygon.npoints == 0) {&lt;br /&gt;
      returnValue = new Polygon();&lt;br /&gt;
    } else {&lt;br /&gt;
      returnValue = new Polygon(polygon.xpoints, polygon.ypoints, polygon.npoints);&lt;br /&gt;
    }&lt;br /&gt;
    return returnValue;&lt;br /&gt;
  }&lt;br /&gt;
  protected void paintComponent(Graphics g) {&lt;br /&gt;
    super.paintComponent(g);&lt;br /&gt;
    g.drawPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoManagerHelper {&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new UndoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager) {&lt;br /&gt;
    return new UndoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.undoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new RedoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager) {&lt;br /&gt;
    return new RedoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.redoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  private abstract static class UndoRedoAction extends AbstractAction {&lt;br /&gt;
    UndoManager undoManager = new UndoManager();&lt;br /&gt;
    String errorMessage = &amp;quot;Cannot undo&amp;quot;;&lt;br /&gt;
    String errorTitle = &amp;quot;Undo Problem&amp;quot;;&lt;br /&gt;
    protected UndoRedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(name);&lt;br /&gt;
      undoManager = manager;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorMessage(String newValue) {&lt;br /&gt;
      errorMessage = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorTitle(String newValue) {&lt;br /&gt;
      errorTitle = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    protected void showMessage(Object source) {&lt;br /&gt;
      if (source instanceof Component) {&lt;br /&gt;
        JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,&lt;br /&gt;
            JOptionPane.WARNING_MESSAGE);&lt;br /&gt;
      } else {&lt;br /&gt;
        System.err.println(errorMessage);&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class UndoAction extends UndoRedoAction {&lt;br /&gt;
    public UndoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot undo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Undo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.undo();&lt;br /&gt;
      } catch (CannotUndoException cannotUndoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class RedoAction extends UndoRedoAction {&lt;br /&gt;
    public RedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot redo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Redo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.redo();&lt;br /&gt;
      } catch (CannotRedoException cannotRedoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
           &lt;br /&gt;
       &amp;lt;/source&amp;gt;&lt;br /&gt;
    &lt;br /&gt;
   &lt;br /&gt;
  &amp;lt;!-- end source code --&amp;gt;&lt;br /&gt;
   &lt;br /&gt;
&lt;br /&gt;
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== UndoableEditSupport: removeUndoableEditListener(UndoableEditListener l) ==&lt;br /&gt;
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   &lt;br /&gt;
  &amp;lt;!-- start source code --&amp;gt;&lt;br /&gt;
   &lt;br /&gt;
    &amp;lt;source lang=&amp;quot;java&amp;quot;&amp;gt;&lt;br /&gt;
import java.awt.BorderLayout;&lt;br /&gt;
import java.awt.ruponent;&lt;br /&gt;
import java.awt.Container;&lt;br /&gt;
import java.awt.Graphics;&lt;br /&gt;
import java.awt.Polygon;&lt;br /&gt;
import java.awt.event.ActionEvent;&lt;br /&gt;
import java.awt.event.MouseAdapter;&lt;br /&gt;
import java.awt.event.MouseEvent;&lt;br /&gt;
import java.awt.event.MouseListener;&lt;br /&gt;
import javax.swing.AbstractAction;&lt;br /&gt;
import javax.swing.Action;&lt;br /&gt;
import javax.swing.JButton;&lt;br /&gt;
import javax.swing.JFrame;&lt;br /&gt;
import javax.swing.JOptionPane;&lt;br /&gt;
import javax.swing.JPanel;&lt;br /&gt;
import javax.swing.JToolBar;&lt;br /&gt;
import javax.swing.UIManager;&lt;br /&gt;
import javax.swing.event.UndoableEditListener;&lt;br /&gt;
import javax.swing.undo.AbstractUndoableEdit;&lt;br /&gt;
import javax.swing.undo.CannotRedoException;&lt;br /&gt;
import javax.swing.undo.CannotUndoException;&lt;br /&gt;
import javax.swing.undo.UndoManager;&lt;br /&gt;
import javax.swing.undo.UndoableEditSupport;&lt;br /&gt;
public class UndoDrawing {&lt;br /&gt;
  public static void main(String args[]) {&lt;br /&gt;
    JFrame frame = new JFrame(&amp;quot;Drawing Sample&amp;quot;);&lt;br /&gt;
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);&lt;br /&gt;
    UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();&lt;br /&gt;
    UndoManager manager = new UndoManager();&lt;br /&gt;
    drawingPanel.addUndoableEditListener(manager);&lt;br /&gt;
    JToolBar toolbar = new JToolBar();&lt;br /&gt;
    JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));&lt;br /&gt;
    toolbar.add(undoButton);&lt;br /&gt;
    JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));&lt;br /&gt;
    toolbar.add(redoButton);&lt;br /&gt;
    Container content = frame.getContentPane();&lt;br /&gt;
    content.add(toolbar, BorderLayout.NORTH);&lt;br /&gt;
    content.add(drawingPanel, BorderLayout.CENTER);&lt;br /&gt;
    frame.setSize(300, 150);&lt;br /&gt;
    frame.setVisible(true);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawEdit extends AbstractUndoableEdit {&lt;br /&gt;
  UndoableDrawingPanel panel;&lt;br /&gt;
  Polygon polygon, savedPolygon;&lt;br /&gt;
  public UndoableDrawEdit(UndoableDrawingPanel panel) {&lt;br /&gt;
    this.panel = panel;&lt;br /&gt;
    polygon = panel.getPolygon();&lt;br /&gt;
  }&lt;br /&gt;
  public String getPresentationName() {&lt;br /&gt;
    return &amp;quot;Polygon of size &amp;quot; + polygon.npoints;&lt;br /&gt;
  }&lt;br /&gt;
  public void redo() throws CannotRedoException {&lt;br /&gt;
    super.redo();&lt;br /&gt;
    if (savedPolygon == null) {&lt;br /&gt;
      // Should never get here, as super() doesn&amp;quot;t permit redoing&lt;br /&gt;
      throw new CannotRedoException();&lt;br /&gt;
    } else {&lt;br /&gt;
      panel.setPolygon(savedPolygon);&lt;br /&gt;
      savedPolygon = null;&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public void undo() throws CannotUndoException {&lt;br /&gt;
    super.undo();&lt;br /&gt;
    savedPolygon = panel.getPolygon();&lt;br /&gt;
    panel.setPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoableDrawingPanel extends JPanel {&lt;br /&gt;
  UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);&lt;br /&gt;
  Polygon polygon = new Polygon();&lt;br /&gt;
  public UndoableDrawingPanel() {&lt;br /&gt;
    MouseListener mouseListener = new MouseAdapter() {&lt;br /&gt;
      public void mouseReleased(MouseEvent mouseEvent) {&lt;br /&gt;
        undoableEditSupport.postEdit(new UndoableDrawEdit(UndoableDrawingPanel.this));&lt;br /&gt;
        polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());&lt;br /&gt;
        repaint();&lt;br /&gt;
      }&lt;br /&gt;
    };&lt;br /&gt;
    addMouseListener(mouseListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void addUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.addUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {&lt;br /&gt;
    undoableEditSupport.removeUndoableEditListener(undoableEditListener);&lt;br /&gt;
  }&lt;br /&gt;
  public void setPolygon(Polygon newValue) {&lt;br /&gt;
    polygon = newValue;&lt;br /&gt;
    repaint();&lt;br /&gt;
  }&lt;br /&gt;
  public Polygon getPolygon() {&lt;br /&gt;
    Polygon returnValue;&lt;br /&gt;
    if (polygon.npoints == 0) {&lt;br /&gt;
      returnValue = new Polygon();&lt;br /&gt;
    } else {&lt;br /&gt;
      returnValue = new Polygon(polygon.xpoints, polygon.ypoints, polygon.npoints);&lt;br /&gt;
    }&lt;br /&gt;
    return returnValue;&lt;br /&gt;
  }&lt;br /&gt;
  protected void paintComponent(Graphics g) {&lt;br /&gt;
    super.paintComponent(g);&lt;br /&gt;
    g.drawPolygon(polygon);&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
class UndoManagerHelper {&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new UndoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getUndoAction(UndoManager manager) {&lt;br /&gt;
    return new UndoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.undoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager, String label) {&lt;br /&gt;
    return new RedoAction(manager, label);&lt;br /&gt;
  }&lt;br /&gt;
  public static Action getRedoAction(UndoManager manager) {&lt;br /&gt;
    return new RedoAction(manager, (String) UIManager.get(&amp;quot;AbstractUndoableEdit.redoText&amp;quot;));&lt;br /&gt;
  }&lt;br /&gt;
  private abstract static class UndoRedoAction extends AbstractAction {&lt;br /&gt;
    UndoManager undoManager = new UndoManager();&lt;br /&gt;
    String errorMessage = &amp;quot;Cannot undo&amp;quot;;&lt;br /&gt;
    String errorTitle = &amp;quot;Undo Problem&amp;quot;;&lt;br /&gt;
    protected UndoRedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(name);&lt;br /&gt;
      undoManager = manager;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorMessage(String newValue) {&lt;br /&gt;
      errorMessage = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    public void setErrorTitle(String newValue) {&lt;br /&gt;
      errorTitle = newValue;&lt;br /&gt;
    }&lt;br /&gt;
    protected void showMessage(Object source) {&lt;br /&gt;
      if (source instanceof Component) {&lt;br /&gt;
        JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,&lt;br /&gt;
            JOptionPane.WARNING_MESSAGE);&lt;br /&gt;
      } else {&lt;br /&gt;
        System.err.println(errorMessage);&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class UndoAction extends UndoRedoAction {&lt;br /&gt;
    public UndoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot undo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Undo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.undo();&lt;br /&gt;
      } catch (CannotUndoException cannotUndoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
  public static class RedoAction extends UndoRedoAction {&lt;br /&gt;
    public RedoAction(UndoManager manager, String name) {&lt;br /&gt;
      super(manager, name);&lt;br /&gt;
      setErrorMessage(&amp;quot;Cannot redo&amp;quot;);&lt;br /&gt;
      setErrorTitle(&amp;quot;Redo Problem&amp;quot;);&lt;br /&gt;
    }&lt;br /&gt;
    public void actionPerformed(ActionEvent actionEvent) {&lt;br /&gt;
      try {&lt;br /&gt;
        undoManager.redo();&lt;br /&gt;
      } catch (CannotRedoException cannotRedoException) {&lt;br /&gt;
        showMessage(actionEvent.getSource());&lt;br /&gt;
      }&lt;br /&gt;
    }&lt;br /&gt;
  }&lt;br /&gt;
}&lt;br /&gt;
           &lt;br /&gt;
       &amp;lt;/source&amp;gt;&lt;br /&gt;
    &lt;br /&gt;
   &lt;br /&gt;
  &amp;lt;!-- end source code --&amp;gt;&lt;/div&gt;</summary>
		<author><name>Admin</name></author>	</entry>

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