如何为我的视频录制应用程序获取服务计时器？

Hi guys i wanted a "service" timer which enable my camera to show the elapsed(incremental) time of a timer when the video recording process has started in such a format 00:00:00? But i do not know how to code the above function in a service activity since it poses the problem of not allowing xml content to link with my mainActivity which in my case is a video recording activity to update the elapsed time on a textview, correct me if i'm wrong or is there a work around/solution? Hi guys i wanted a "service" timer which enable