Is it possible to dynamically move (center on the screen) buttons or other objects when the orientation changes. I know the onCreate is called when the orientation changes but i am not able to change the x or y coordinates of the buttons. What do others do, do you make two layouts for each activity (one for each orientation)?

If you just want to have a different setup for each orientation, the simpler is indeed to have two layout files.

If you want to know more on this subject, there is a good tutorial here :
Rotational Forces