java - 如果没有 @Provides- 或 @Produces-annotated 方法，则无法提供 Dagger 2 Activity

Question

我是 Dagger 的新手，我正在尝试实现一个继承自进行注入(inject)的类的类。当我在 MainActivity 中取出一个组件的注入(inject)并从 BaseActivity 继承它时，事情就崩溃了。

我的应用组件类:

@Singleton
@Component(modules = {NetworkModule.class, ApplicationModule.class, 
AndroidModule.class})
public interface AppComponent {

   void inject (BaseActivity baseActivity);
   void inject (MainActivity mainActivity);
}
}

我的 ActivityModule 类:

@Module
public class ActivityModule {

private Activity activity;

public ActivityModule(Activity activity) {
    this.activity = activity;
}

@PerActivity
@Provides
@ActivityContext
public Context provideContext() {
    return activity;
}
}

我的 ApplicationModule 类:

@Module
public class ApplicationModule {

private Application application;

public ApplicationModule(Application application) {
    this.application = application;
}

@Provides
@Singleton
@ApplicationContext
public Context provideContext() {
    return this.application;
}

@Provides
@Singleton
public FCMTokenHelper provideFCMTokenHelper(Context context, ApiService apiService) {
    UserRepoImpl userRepo = new UserRepoImpl(apiService);
    return new FCMTokenHelper(context, context.getClass().getSimpleName(), userRepo);
}

@Provides
@Singleton
public UserRepoContract providerUserRepo(ApiService apiService) {
    return new UserRepoImpl(apiService);
}

}

我的两个类(class)(都在 kotlin 中)

class MainActivity : BaseActivity() { 

}

abstract class BaseActivity : AppCompatActivity(), GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, ActivityCompat.OnRequestPermissionsResultCallback, LocationListener {

   @Inject
   lateinit var userRepo: UserRepoContract

   @Inject
   internal var tokenHelper: FCMTokenHelper? = null
}

错误:

Error:(51, 10) error: .BaseActivity cannot be provided without an @Provides-annotated method. BaseActivity is injected at AppComponent.inject(baseActivity) Error:(75, 10) error: MainActivity cannot be provided without an @Inject constructor or from an @Provides-annotated method. MainActivity is injected at .AppComponent.inject(mainActivity)

使用 Dagger 2 版本 2.9安卓工作室 3.0Kotlin 和 Java

Answer 1

我的问题在这里:

@Inject
internal var tokenHelper: FCMTokenHelper? = null

将其更改为:

@Inject
lateinit var tokenHelper: FCMTokenHelper

修复了问题。看个好解释here.