marco0305,

Everything must be loaded, declared, and initialized in each activity. For reusable code, you'll need to use eval(), include(), or libraries in each activity. Use setGlobal() and getGlobal() for saving any values that must survive loading (or reloading) an activity.

The home activity will always be executed after a reboot or fresh download. getGlobal() will return null if the global is not yet defined. You can use this to conditionally set up your globals.