private void updateListeners() {
    ScrollPaneUI ui = scrollPane.getUI();
    if (ui != lastUI) {
        // Update "ui" property listener
        if (ui != null) {
            // Check mouse wheel listeners on scroll pane.
            // Pair first non-MWDelegator listener with 
            // Remove any other delegators than this one.
            MouseWheelListener[] mwls = scrollPane.getListeners(MouseWheelListener.class);
            if (LOG.isLoggable(Level.FINE)) {
                LOG.log(Level.FINE, "MouseWheelDelegator.updateListeners(): scrollPane change scrollPane={0}, MouseWheelListeners:{1}\n",
                        new Object[]{obj2String(scrollPane), Arrays.asList(mwls)});
            }
            delegateListener = null;
            for (MouseWheelListener listener : mwls) {
                if (listener instanceof MouseWheelDelegator) {
                    scrollPane.removeMouseWheelListener(listener);
                    if (delegateListener == null) {
                        delegateListener = ((MouseWheelDelegator) listener).delegateListener;
                        scrollPane.addMouseWheelListener(this);
                    }
                } else { // Regular listener 
                    // Current patch only assumes one MW listener attached by the UI impl.
                    if (delegateListener == null) {
                        delegateListener = listener;
                        scrollPane.removeMouseWheelListener(listener);
                        scrollPane.addMouseWheelListener(this);
                    }
                }
            }
        }
        lastUI = ui;
    }
}
 

/**
 * Maps {@code JScrollPane.getUI()} through queue
 */
public ScrollPaneUI getUI() {
    return (runMapping(new MapAction<ScrollPaneUI>("getUI") {
        @Override
        public ScrollPaneUI map() {
            return ((JScrollPane) getSource()).getUI();
        }
    }));
}
 

/**
 * Maps {@code JScrollPane.setUI(ScrollPaneUI)} through queue
 */
public void setUI(final ScrollPaneUI scrollPaneUI) {
    runMapping(new MapVoidAction("setUI") {
        @Override
        public void map() {
            ((JScrollPane) getSource()).setUI(scrollPaneUI);
        }
    });
}
 

@Override
public void setUI(ScrollPaneUI ui) {
  super.setUI(ui);
  updateViewportBorder();
}
 

@Override
public void setUI(ScrollPaneUI ui) {
  super.setUI(ui);
  // disable standard Swing keybindings
  setInputMap(WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, null);
}