Question

My Android app comes both as a free and paid version. I have created a library project and two additional Application projects, one ‘Free’ and one ‘Paid’ version (signed with the same key, of course). Note that these Application projects are pretty much empty, no settings etc. Hence, the library contains 99% of the code.

My app creates both an SQLite database and a SharedPreferences file with user data. Is it possible to copy these files between the free and paid versions? (The preferences are more important than the database.)

E.g.

1. User runs the free version. A database and configuration file are created.
2. User installs the paid version and runs it.
3. The paid version checks for any free version data and copies it. This is what I want!

Answer 1

1. Implement a ContentProvider to expose the stored data in your free version.
2. Ensure the provider is exported (android:exported=”true”)
3. Declare a permission in your client application. The protection level should be “signature”.
4. Require the permission declared in (3) as a readPermission for the provider.
5. In your paid app, add a uses-permission for the permission declared in your free app.
6. Check for the presence of the provider & load the data into your paid app.

This, of course, only works if you are signing the free and paid apps with the same cert (which most sane people do).