如何收听JCombobox选择事件

Question

当我选择JCombobox我想要处理事件时,当它被选中并显示下拉列表以及当下拉消失并且JCombobox取消选择时处理事件.

注意,我不打算听取项目选择更改,但是当用户选择JCombobox并且UI弹出Dropdown时.

Answer 1

您想使用addPopupMenuListener,它使用以下接口:

public interface PopupMenuListener extends EventListener {

    /**
     *  This method is called before the popup menu becomes visible 
     */
    void popupMenuWillBecomeVisible(PopupMenuEvent e);

    /**
     * This method is called before the popup menu becomes invisible
     * Note that a JPopupMenu can become invisible any time 
     */
    void popupMenuWillBecomeInvisible(PopupMenuEvent e);

    /**
     * This method is called when the popup menu is canceled
     */
    void popupMenuCanceled(PopupMenuEvent e);
}