I tried to search for the size of Text type in SQLite Database on Android, but I still not understand.
Can anyone teach me about that?

1. size of Text type in Android database
2. instead of Text, can we use Varchar type?
3. Is there any document about database design for Android?

Thanks a lot!
Best wishes!

1/2. I can't speak directly about SQLite on Android, but have you looked at http://sqlite.org ? It describes how the database works in general. There is a document on SQLite limits you may find useful, as well as the FAQ. So far with my first app I've not hit size problems storing text in a Text field.

3. Have you looked at the tutorial? It uses SQLite.