Why @ContributesAndroidInjector doesn't provide Android Framework type

Question

I have simplified my application to get the root of the problem and here is the simplified version. I\'m implementing Dagger 2 using following configuration:

App

Answer 1

You probably forgot to inject your application in MyApp. You should have something like this (you might need to modify it a bit to fit your AppComponent:

DaggerAppComponent.builder()
    .application(this)
    .build()
    .inject(this)

Also, Dagger is actually providing your MainActivity through your @ContributesAndroidInjector annotated method but that's not what you're injecting.

You're injecting a string so Dagger is using your provideString method. Since this method requires a MainActivity instance to work, Dagger is looking for such a method annotated with @Provides. You don't have any and Dagger won't look at your @ContributesAndroidInjector method since it does not have any reasons to do so.

If you want it to work, you actually have to define your provideString method in a separate module and install it inside your @ContributesAndroidInjector:

@Module
abstract class ActivityBindingModule {
    @ContributesAndroidInjector(modules = [StringModule::class])
    abstract fun mainActivity(): MainActivity
}

@Module
class StringModule {

    @JvmStatic
    @Provides
    fun provideString(mainActivity: MainActivity): String = "Hehe"
}