Dagger 2错误：依赖项“不能在没有@inject构造函数的情况下提供”，而它实际上是用@inject注释的

Question

@Singleton
@Subcomponent(
        modules = {
                NavigationDrawerModule.class,
                NavigationListModule.class,
                SwitcherModule.class
        }
)
public interface NavigationDrawerComponent {


    NavigationDrawerFragment inject(NavigationDrawerFragment object);

}

@Module
public class NavigationDrawerModule {

    private final Activity activity;
    private final View rootView;
    private final LoaderManager loaderManager;

    public NavigationDrawerModule(Activity activity, View rootView, LoaderManager loaderManager) {
        this.activity = activity;
        this.rootView = rootView;
        this.loaderManager = loaderManager;
    }

    @Provides @Singleton EventBus provideLocalBus() {
        return EventBus.builder().build();
    }

    @Provides @Singleton View provideViewRoot() {
        return rootView;
    }

    @Provides @Singleton LoaderManager provideLoaderManager() {
        return loaderManager;
    }

    @Provides @Singleton Context provideContext() {
        return activity;
    }
}

第二个模块如下所示--它为屏幕上的UI子集提供演示者/控制器及其依赖关系：

@Module
public class SwitcherModule {

    @Provides SwitchController provideSwitcherController(SwitchControllerImpl impl) {
        return impl;
    }

    @Provides SwitcherView provideSwitcherView(SwitcherViewImpl impl) {
        return impl;
    }

}

第三个模块-用于UI子集的另一个演示器/控制器：

@Module
public class NavigationListModule {

    @Provides @Singleton NavigationListController provideNavigationListController(NavigationListControllerImpl impl) {
        return impl;
    }

    @Provides @Singleton NavigationListView provideNavigationListView(NavigationListViewImpl impl) {
        return impl;
    }
}

正在注入的片段的相关部分：

@Inject SwitchController identitySwitchController;
@Inject SwitcherView identitySwitcherView;
@Inject NavigationListController navigationListController;
@Inject NavigationListView navigationListView;

@Inject
public NavigationListControllerImpl(Context ctx, EventBus bus) {
    this.ctx = ctx;
    this.bus = bus;
}

error: ...sidenavigation.navigationlist.NavigationListControllerImpl cannot be provided without an @Inject constructor or from an @Provides-annotated method.
...sidenavigation.NavigationDrawerFragment.navigationListController
[injected field of type: ...sidenavigation.navigationlist.NavigationListController navigationListController]
...sidenavigation.navigationlist.NavigationListModule.provideNavigationListController(...sidenavigation.navigationlist.NavigationListControllerImpl impl)
[parameter: ...sidenavigation.navigationlist.NavigationListControllerImpl impl]

提前谢谢！

Answer 1

我得到了同样的错误，因为我忘记了将父组件中的模块提供的对象公开给依赖于它的其他组件。

父组件示例：

@Singleton
@Component(modules = {AppModule.class})
public interface AppComponent {
    AppPref exposeAppPref(); /* my issue was caused by forgot this line,
the method name doesn't matter, what matters is the object type AppPref provided in the AppModule 
that you want it to be available in the component that declares this component as one of its dependencies*/
}

使上述组件作为依赖项的示例组件

@UserScope
@Component (dependencies = {AppComponent.class})
public interface ActivityComponent {
    void inject(MainActivity activity);
}

...
    @Provides
    @Singleton
    AppPref provideAppPref() {
        return appPref;
    }
...