Android static fields can be reset if the app is backgrounded

An Android app I'm working on uses static fields to store data that it downloads at launch. This was working great during development, but after release I observed a lot of null-reference crashes when accessing those static fields. When Android needs to free memory, it terminates processes belonging to apps that aren't currently visible to the user; when the user resumes the app, Android restores the stack of activities, but the process itself is new. Therefore, static fields get reset.

To fix my problem, I wrote a function that checks whether the static data is gone, and if so, launches the activity responsible for downloading the data. I tweaked all activities that require the static data to call this function before doing anything in onCreate or onStart, bailing out if the function indicates that the data needs to be reloaded. An argument to the intent used to relaunch the loading activity indicates whether the loader should just finish() instead of starting a new instance of the main activity.