JScrollPopupMenu.java 文件源码

protected JScrollBar getScrollBar() {
    if (popupScrollBar == null) {
        popupScrollBar = new JScrollBar(JScrollBar.VERTICAL);
        popupScrollBar.addAdjustmentListener(new AdjustmentListener() {
            @Override
            public void adjustmentValueChanged(AdjustmentEvent e) {
                doLayout();
                repaint();
            }
        });

        popupScrollBar.setVisible(false);
    }

    return popupScrollBar;
}