The Undo Framework - The Definitive Guide to Java Swing - page 776

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 {
public RedoAction(UndoManager manager, String name) {
super(manager, name);
setErrorMessage("Cannot redo");
setErrorTitle("Redo Problem");
}