Android，在哪里放置我的UI更新和我的游戏循环

So I'm new to Android, and have been having some difficulties with understanding threading/Android UI updating and such. I have some code for a simple game engine I made for an AP computer science final project and I have been trying to make it into an Android app. Coming from the java world I'm not used to threading or worrying about how much time or where a calculation is taking place so I've been having some difficulties getting my game playable. After a splash screen and a main menu, I have it set up so an activity named "Play" starts. In this activity I have found that I can initialize my game engine object(which gets passed from class to class), create an object I created to make an AsyncTask("GuiThreader" in the code linked below) but as soon as I throw in some code in "Play" to do anything more than that (like initialize a button, or start the threader helper class) I get an "Activity has Stopped Unexpectedly" error meaning I'm doing something wrong. I've been looking at a lot of the Android example code but its making little sense to me. So I guess with all that background my bigger question is how can I get this code working? More specifically where should I have my loop that checks when the game is over, and how can I update my button colors outside of the "main" threader to keep it from crashing. So I'm new to Android, and have been having som