Manage code/build for Android app stores (Google/Amazon/etc)?

Question

I have an Android app that's downloaded primarily from Android Market (now, Google Play). We made a few tweaks to the source and also submitted to the Amazon App Store to see what sort of traction it gets. I'm now looking for a sustainable way to develop from a common code base and yet build so that I can submit to either/both.

Amazon's store has some restrictions about available APIs, and hence I'd like to conditionally remove/modify features from that version. Since Java doesn't support traditional conditional compilation, and conditionally including files in Eclipse doesn't seem trivial (is it even possible?), I wanted to ask what others are doing to solve this.

Admittedly, I'm no Eclipse/Java expert so feel free to school me.

What I'm looking for in a solution:

• Building/debugging using Eclipse.
• Static code files, with environment/settings toggles to control what to build.
• No duplicate code or conditional logic in code to pick code flow at runtime

Is this something you've solved for Android apps specifically, or for other Java/Eclipse based projects? Suggestions for where to begin?

Answer 1

It's quite easy to do in the newest versions of ADT (version 17), though I do find it makes compilation a bit longer:

1. Create a new Android project (proj-A)
2. Go to Project->Properties, select Android, and check "Is Library"
3. Move all your common code to proj-A, import all the necessary libraries
4. Create a new Android project for Google Play (proj-B)
5. Go to Project->Properties, select Android, and add Proj-A to the Library
6. Repeat #4&5 for the Amazon version

If you have some variables that should be set differently for each sub project (i.e. boolean GOOGLE_PLAY_VERSION to enable Google Play specific functions), you have to create another project to contain these values since you can't have projects that reference one-another in a circular fashion. You can solve this by adding the following steps:

1. Pull all of your sub-project specific variables into one or more Classes that just serves as container(s) for these variables
2. Create a "dummy" Java project (dummy)
3. Config proj-A to add a new Source link to the bin directory of dummy
4. Add the config Classes in each sub-project with project-specific changes
5. Profits!

Note that the variables in dummy should not be set as final, otherwise it will override sub-project's setting.

This may seem like quite a bit of up-front work, but has worked quite well for me as far as version control goes.

Edit: Now with Google's move to Android Studio & Gradle, it may be better to move to that if you are starting a new project if you want to support multiple APKs, see Android dev site's Building Your Project with Gradle#Work with build variants. It definitely doesn't hurt to evaluate that option before deciding.