public static void main(String[] argv) {
JFrame dlg = new JFrame();
dlg.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
UndoDemo demo = new UndoDemo();
dlg.getContentPane().add("Center", demo);
dlg.getContentPane().add("North", demo.createToolBar());
dlg.pack();
dlg.setVisible(true);
}
public void redo() {
instance.drawing.add(this);
instance.repaint();
}
public void undo() {
instance.drawing.remove(this);
instance.repaint();
}
