TrayIcon显示消息在mac中弹出一个窗口

I am creating a creating java app in which I am displaying a Ballon message in system tray / notification bar. It displays a balloon message properly in windows(the balloon auto fades away in seconds) but on Mac machine it displays a window(which has to be closed purposely by the user). How can I achieve the same effect on Mac? I am creating a creating java app in which I am