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);
}}