CODEWITHSUNDEEP
javaandroidmvvmdagger-2android-architecture-components
Pramod Moolekandathil
Pramod Moolekandathil

Reputation: 589

Not able to inject ViewModel with dagger2 android java

I am trying to inject viewmodel with help of a common ViewModelProviderFactory in dagger2. (This is my first app with dagger and architecure components) This is the error i get when i build the code.

Error:(26, 10) error: java.util.Map,javax.inject.Provider> cannot be provided without an @Provides-annotated method.

enter image description here

Here is the code i use

ViewModelProviderFactory

@PerActivity

public class ViewModelProviderFactory implements ViewModelProvider.Factory {

    private final Map<Class<? extends ViewModel>, Provider<ViewModel>> creators;

    @Inject
    public ViewModelProviderFactory(Map<Class<? extends ViewModel>, Provider<ViewModel>> creators) {
        this.creators = creators;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T extends ViewModel> T create(Class<T> modelClass) {
        Provider<? extends ViewModel> creator = creators.get(modelClass);
        if (creator == null) {
            for (Map.Entry<Class<? extends ViewModel>, Provider<ViewModel>> entry : creators.entrySet()) {
                if (modelClass.isAssignableFrom(entry.getKey())) {
                    creator = entry.getValue();
                    break;
                }
            }
        }
        if (creator == null) {
            throw new IllegalArgumentException("unknown model class " + modelClass);
        }
        try {
            return (T) creator.get();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

ViewModelModule

@Module
public abstract class ViewModelModule {
    @Binds
    @IntoMap
    @ViewModelKey(HomeViewModel.class)
    abstract ViewModel bindHomeViewModel(HomeViewModel homeViewModel);

    @Binds
    abstract ViewModelProvider.Factory bindViewModelFactory(ViewModelProviderFactory factory);
}

ApplicationComponent

@Singleton
@Component(modules = {ApplicationModule.class, ViewModelModule.class})
public interface ApplicationComponent {

    void inject(BaseApp app);

    @ApplicationContext
    Context getContext();

    Application getApplication();

    WebService getWebService();

    PreferencesHandler getPreferencesHandler();

    InternetUtils getInternetUtils();
}

ActivityComponent

@PerActivity
@Component(dependencies = ApplicationComponent.class, modules = ActivityModule.class)
public interface ActivityComponent {

    void inject(MainActivity mainActivity);

    void inject(SampleListActivity sampleListActivity);

    void inject(HomeActivity homeActivity);
}

ViewModelKey

@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@MapKey
public @interface ViewModelKey {
    Class<? extends ViewModel> value();
}

In my activity i use this code

@Inject
ViewModelProviderFactory mViewModelFactory;
........
oncreate(){
...
homeViewModel = ViewModelProviders.of(this,mViewModelFactory).get(HomeViewModel.class);
.......
}

Upvotes: 3

Views: 978

Answers (1)

David Medenjak
David Medenjak

Reputation: 34532

Your ActivityComponent is a Component (not a SubComponent) with a dependency on ApplicationComponent, so it has no access to the Map set up in the AppComponent.

Either switch to using a SubComponent for your ActivityComponent, or make sure to include a provision method for Map<Class<? extends ViewModel>, Provider<ViewModel>> in your AppComponent so that dependent components can access it.

interface AppComponent {
  // ..
  Map<Class<? extends ViewModel>, Provider<ViewModel>> creators();
}

Upvotes: 3

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