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<TITLE>Adding Undo and Redo to a Text Component (Java Developers Almanac Example)
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<B><A HREF="../javax.swing.undo/pkg.html">javax.swing.undo</A></B><font color="#666666" class="xsmall-font">
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<h3>e1034. Adding Undo and Redo to a Text Component</h3>
The Swing toolkit contains an undo manager that can be added
to a <code>Document</code> object to provide undo and redo capabilty.
This example adds undo capability to a <code>JTextArea</code> component.
The example binds the undo action to control-Z and the redo action
to control-Y.
<pre> JTextComponent textcomp = new <font color="#0066ff"><i>JTextArea()</i></font>;
final UndoManager undo = new UndoManager();
Document doc = textcomp.getDocument();
// Listen for undo and redo events
doc.addUndoableEditListener(new UndoableEditListener() {
public void undoableEditHappened(UndoableEditEvent evt) {
undo.addEdit(evt.getEdit());
}
});
// Create an undo action and add it to the text component
textcomp.getActionMap().put(<font color="#0066ff"><i>"Undo"</i></font>,
new AbstractAction(<font color="#0066ff"><i>"Undo"</i></font>) {
public void actionPerformed(ActionEvent evt) {
try {
if (undo.canUndo()) {
undo.undo();
}
} catch (CannotUndoException e) {
}
}
});
// Bind the undo action to ctl-Z
textcomp.getInputMap().put(KeyStroke.getKeyStroke(<font color="#0066ff"><i>"control Z"</i></font>), <font color="#0066ff"><i>"Undo"</i></font>);
// Create a redo action and add it to the text component
textcomp.getActionMap().put(<font color="#0066ff"><i>"Redo"</i></font>,
new AbstractAction(<font color="#0066ff"><i>"Redo"</i></font>) {
public void actionPerformed(ActionEvent evt) {
try {
if (undo.canRedo()) {
undo.redo();
}
} catch (CannotRedoException e) {
}
}
});
// Bind the redo action to ctl-Y
textcomp.getInputMap().put(KeyStroke.getKeyStroke(<font color="#0066ff"><i>"control Y"</i></font>), <font color="#0066ff"><i>"Redo"</i></font>);
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