ActivityBuilder

@Module
public abstract class ActivityBuilder {

    @ContributesAndroidInjector(modules = MainActivityModule.class)
    abstract MainActivity bindMainActivity();

    @ContributesAndroidInjector(modules = {DetailActivityModule.class, DetailFragmentProvider.class})
    abstract DetailActivity bindDetailActivity();

}

Android Injector

note that AndroidInjection.inject(this); is called before onCreate

public class MainActivity extends AppCompatActivity implements MainView{
    @Inject
    MainPresenter mainPresenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        AndroidInjection.inject(this);
        super.onCreate(savedInstanceState);
        ....
    }
}