SQLiteOpenHelper-Android Confusion

Question

I have couple of question regarding to sqlite-android

1. When is the onUpgrade method called in application?

2. Can I have two helper class in one application? if so...

3. then how/when I call second class

Answer 1

onUpgrade is called when int DATABASE_VERSION of your DBAdapter is higher than the currenly installed one.

Why would you want 2 helper classes. But yes, I suppose you could.