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import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.UndoManager;
public class UndoEditor extends JFrame {
private UndoManager undoManager = new UndoManager();
private JMenuBar menuBar = new JMenuBar();
private JMenu editMenu = new JMenu("Edit");
private UndoAction undoAction = new UndoAction();
private RedoAction redoAction = new RedoAction();
public UndoEditor() {
setLayout(new BorderLayout());
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextPane editor = new JTextPane();
editor.getDocument().addUndoableEditListener(new UndoListener());
JScrollPane scroller = new JScrollPane(editor);
menuBar.add(editMenu);
editMenu.add(undoAction);
editMenu.add(redoAction);
this.setJMenuBar(menuBar);
add(scroller);
setSize(400, 300);
setVisible(true);
}
public static void main(String[] args) {
new UndoEditor();
}
class UndoListener implements UndoableEditListener {
public void undoableEditHappened(UndoableEditEvent e) {
undoManager.addEdit(e.getEdit());
undoAction.update();
redoAction.update();
}
}
class UndoAction extends AbstractAction {
public UndoAction() {
this.putValue(Action.NAME, undoManager.getUndoPresentationName());
this.setEnabled(false);
}
public void actionPerformed(ActionEvent e) {
if (this.isEnabled()) {
undoManager.undo();
undoAction.update();
redoAction.update();
}
}
public void update() {
this.putValue(Action.NAME, undoManager.getUndoPresentationName());
this.setEnabled(undoManager.canUndo());
}
}
class RedoAction extends AbstractAction {
public RedoAction() {
this.putValue(Action.NAME, undoManager.getRedoPresentationName());
this.setEnabled(false);
}
public void actionPerformed(ActionEvent e) {
if (this.isEnabled()) {
undoManager.redo();
undoAction.update();
redoAction.update();
}
}
public void update() {
this.putValue(Action.NAME, undoManager.getRedoPresentationName());
this.setEnabled(undoManager.canRedo());
}
}
}
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