没有@Provides注释的方法就无法提供对象

Question

I've started to setup Dagger 2 and faced a strange issue that looks like a bug to me.

I have 1 main component and 1 subcomponent which I 'plus' in parent component.

I use:

compile "com.google.dagger:dagger:2.4"
apt "com.google.dagger:dagger-compiler:2.4"
annotationProcessor "com.google.dagger:dagger-compiler:2.4"

Application component is prety easy. It just 'plus' the subcomponent:

@Singleton @Component(modules = { AristocratsAppModule.class })
public interface AristocratsAppComponent {
  StreamComponent plus(StreamModule module);
}

Application module also quite basic. It provides application level dependancies:

@Module public class AristocratsAppModule {
  private static AristocratsApp app;

  public AristocratsAppModule(AristocratsApp app) {
    AristocratsAppModule.app = app;
  }

  @Provides @Singleton AristocratsApp providesApplication() {
    return app;
  }

  @Provides @Singleton GsonXml providesGsonXml() {
    return ...
  }

  @Provides @Singleton @Named("aristocrats") Retrofit providesAristocratsRetrofit() {
    return ...
  }

  @Provides @Singleton @Named("last_fm") Retrofit providesLastFmRetrofit() {
    return ...
  }
}

Subcomponent has two StreamServices (Retrofit services) and simple inject:

@PerController @Subcomponent(modules = { StreamModule.class }) public interface StreamComponent {
  void inject(StreamsController streamsController);

  AristocratsStreamService providesAristocratsStreamService();

  LastFmStreamService providesLastFmStreamService();
}

Module of subcomponent provides presenter injection and two different injections of Retrofit services:

@Module public class StreamModule {
  private StreamsController mView;

  public StreamModule(StreamsController view) {
    mView = view;
  }

  @Provides @PerController StreamMvp.Presenter providesPresenter(StreamCase streamCase,
      StreamModelMapper streamMapper) {
    return new StreamPresenter(mView, streamCase, streamMapper);
  }

  @Provides @PerController AristocratsStreamService providesAristocratsStreamService(
      @Named("aristocrats") Retrofit retrofit) {
    return retrofit.create(AristocratsStreamService.class);
  }

  @Provides @PerController LastFmStreamService providesLastFmStreamService(
      @Named("last_fm") Retrofit retrofit) {
    return retrofit.create(LastFmStreamService.class);
  }
}

Application injection that I call in onCreate() of my app class:

mAppComponent = DaggerAristocratsAppComponent.builder()
        .aristocratsAppModule(new AristocratsAppModule(this))
        .build();

View injection that I call in my controller:

getAppComponent().plus(new StreamModule(this)).inject(this);

Exception that I'm getting during build:

Error:(13, 8) error: [com.qsoft.streams.presentation.di.StreamComponent.inject(com.qsoft.streams.presentation.StreamsController)] com.qsoft.streams.data.network.AristocratsStreamService cannot be provided without an @Provides-annotated method.
com.qsoft.streams.data.network.AristocratsStreamService is injected at
com.qsoft.streams.data.network.StreamApi.<init>(…, streamServiceAristocrats, …)
com.qsoft.streams.data.network.StreamApi is injected at
com.qsoft.streams.data.repository.StreamRepository.<init>(streamApi, …)
com.qsoft.streams.data.repository.StreamRepository is injected at
com.qsoft.streams.domain.interactors.StreamCase.<init>(streamRepository)
com.qsoft.streams.domain.interactors.StreamCase is injected at
com.qsoft.streams.presentation.di.StreamModule.providesPresenter(streamCase, …)
com.qsoft.streams.presentation.StreamMvp.Presenter is injected at
com.qsoft.streams.presentation.StreamsController.mPresenter
com.qsoft.streams.presentation.StreamsController is injected at
com.qsoft.streams.presentation.di.StreamComponent.inject(streamsController)
A binding with matching key exists in component: com.qsoft.streams.presentation.di.StreamComponent

Error complaints about missing @Provides-annotated method but they are inside my child module. Seems that Dagger2 just does not see them. I was thinking that the problem could be in the missing declaration of the AristocratsStreamService in subcomponent, so I even added it there but nothing changed.

This situation looks very strange and I would like to hear some inputs from more experienced Dagger2 developers.

Thank you in advance!

Answer 1

I have noticed that you did not set subcomponents part in AristrocratsModule.

This:

@Module public class AristocratsAppModule {

into this:

@Module(subcomponents = {StreamComponent.class})
public class AristocratsAppModule {

Try to make the following changes. In your StreamComponent create a Builder.

@Subcomponent.Builder
interface Builder {
    Builder streamModule(StreamModule module);

    StreamComponent build();
}

Eventually you will be injecting everything via StreamComponent, and it will inject everything in AristocratsAppComponent as well.

public StreamComponent getStreamComponent(Controller controller) {
    return getAppComponent().streamBuilder().streamModule(new StreamModule(controller)).build();
}

Plus thing can be removed after this.