Comment bouger deux jscrollbar simultanément

p1.getViewport().addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
Point p = p1.getViewport().getViewPosition();
p2.getViewport().setViewPosition(p);
}
});

p2.getViewport().addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
Point p = p2.getViewport().getViewPosition();
p1.getViewport().setViewPosition(p);
}
});