Using HiltAndroidApp annotation within the library module

Hi, I’m trying to integrate Hilt in a multi-module android project(we don’t use feature modules). Here is a current structure of our project

• App Module
• Lib Module 1 (This library has Application class MyApplication1 for app 1)
• Lib Module 2 (This library has Application class MyApplication2 for app 2)
• Lib module 3 (common stuff)
• Up to Lib module 100

If I put @HiltAndroidApp annotation on MyApplication1 I get this build error:

Application class annotated with @HiltAndroidApp has to be defined in an android application project
  [Hilt] Processing did not complete. See error above for details.

To address this issue, if I move the application classes MyApplication1 and MyApplication2 to the App module, I’ll start getting circular dependency errors(because a library project cannot depend on App project). I’ve dozens of libraries and they have code(e.g. lateinit var app: MyApplication1, access app specific properties, etc.) which needs a reference to the Application object, hence I cannot have independent Application classes. If you are suggesting to refactor our code base to have independent Application module, then that would likely be a year long project(given how large our code base is)

I also tried creating a separate app module(not library module) holding a base Application and made my MyApplication1 and MyApplication2 extend it, but I can’t do that successfully, because Android Studio doesn’t like a library-module depend on an application-module. And having a library-module depend on app-module doesn’t sound like a good pattern, and going to cause other issues anyway.

I came across this issue but the suggested solution on the issue won’t work in my case(due to reasons mentioned above).

Will Hilt ever support annotating an Application class with @HiltAndroidApp within the library modules?

[grkep]

@hubtwork thanks for taking time to respond. I get that refactoring is a correct next step. I tried some quick refactoring, and the errors disappeared, and I was able to get some basic injection working. One gotcha, I would like to share w.r.t. multi-module setup is the hilt dependency. Such that, I had to add hilt dependencies implementation "com.google.dagger:hilt-android:$hilt_version" kapt "com.google.dagger:hilt-android-compiler:$hilt_version" to the build.gradle of each module(where I wanted injection), in addition to adding the dependencies in the root build.gradle. A common library with dependencies in the form of api "com.google.dagger:hilt-android:$hilt_version" kapt "com.google.dagger:hilt-android-compiler:$hilt_version" didn’t work(Got null references for dependency in this case, no compile time errors). If someone has any idea about not repeating the dependencies, please do share!

[hubtwork]

@grkep hmm… in my knowledge, it isn’t bug. Hilt is android-wrapper for dagger, and dagger designed with some inconvenience ( as you said, repeating dependencies, etc ) but with best convenience for Dependency Injection by source-auto generating processors.