继承和泛型和 Dagger2

Question

我有两种片段。其中一个是ListFragment，另一个是ListWithFilterFragment，即ListWithFilterFragment extend ListFragment。我也有两个演示者来处理这些片段ListWithFilterPresenter extend ListPresenter。所以我在 Dagger 中为演示者和单独的组件定义了单独的模块。我想向这些片段注入正确的演示者，但出现错误

这是ListFragment：

public class ListFragment<V extends ListView> extends BaseFragment<V, ListPresenter<V>> implements ListView {
    @Inject
    ListPresenter presenter;

    @NonNull
    @Override
    public ListPresenter createPresenter() {
    DaggerListComponent.builder().build().inject((ListFragment<ListView>) this);
    return presenter;
}

这是ListWithFilterFragment：

public class ListWithFilterFragment extends ListFragment<ListWithFilterView> implements ListWithFilterView {
    @Inject
    ListWithFilterPresenter presenter;

    @NonNull
    @Override
    public ListWithFilterPresenter createPresenter() {
        DaggerListWithFilterComponent.builder().build().inject(this);
        return presenter;
    }
}

这是ListComponent：

@Singleton
@Component(modules = {ListPresenterModule.class, 
ListInteractorModule.class})
public interface ListComponent {
    void inject(ListFragment<ListView> fragment);
}

这是ListWithFilterComponent：

@Singleton
@Component(modules = {ListWithFilterPresenterModule.class, 
ListInteractorModule.class})
public interface ListWithFilterComponent {
    void inject(ListWithFilterFragment fragment);
}

和我的演示者模块

@Module
public class ListWithFilterPresenterModule {
    @Provides @NonNull @Singleton
    public ListWithFilterPresenter providePresenter(ListInteractor interactor) {
        return new ListWithFilterPresenter(interactor);
    }
} 

@Module
public class ListPresenterModule {
    @Provides @NonNull @Singleton
    public ListPresenter providePresenter(ListInteractor interactor) {
        return new ListPresenter(interactor);
    }
}

错误：(16, 10) 错误：如果没有 @Provides- 或 @Produces-annotated.method.com.sober.appModules.List.presenter.ListPresenter，则无法提供 com.sober.appModules.List.presenter.ListPresenter被注射在 com.sober.appModules.List.ui.ListFragment.presenter com.sober.appModules.List.ui.ListWithFilterFragment 在 com.sober.appModules.List.injection.ListWithFilterComponent.inject(fragment) 处注入

Answer 1

Dagger 不进行部分注射。要么它可以提供所有的对象，要么它会因为无法提供而失败。

在您的情况下，ListWithFilterComponent 无法将 ListPresenter 提供给 ListWithFilterFragment，或者更确切地说是其 ListFragment 父级。

见行尾的 cmets

error: List.presenter.ListPresenter cannot be provided without an @Provides- or @Produces-annotated.method.
List.presenter.ListPresenter is injected at  <- missing object
List.ui.ListFragment.presenter <- field in parent that is getting injected
List.ui.ListWithFilterFragment is injected at <- object it tries to inject
List.injection.ListWithFilterComponent.inject(fragment) <- component that's missing something

如果您想保留当前设置，您还需要从您的ListWithFilterComponent 提供ListPresenter，否则您需要重构您的片段，以便它们不会相互扩展。