android - 使用 Dagger2 将适配器注入(inject) fragment

Question

我已经按照 Android 架构蓝图 Dagger2 进行依赖注入(inject):https://github.com/googlesamples/android-architecture/tree/todo-mvp-dagger

现在我想将 Adapter 注入(inject)到我的 Fragment 类中:

@ActivityScoped
class MainFragment @Inject
constructor(): DaggerFragment() {

    @Inject lateinit var adapter : ArtistAdapter 
}

我在模块类中有以下内容:

@Module
abstract class MainModule {
    @FragmentScoped
    @ContributesAndroidInjector
    internal abstract fun mainFragment(): MainFragment

    @Module
    companion object {
        @Provides
        @ActivityScoped
        @JvmStatic internal fun provideArtistAdapter() = ArtistAdapter()
    }
}

但由于某些原因，它无法在 RecyclerView 中显示数据。当我不使用注入(inject)而只是使用 val adapter = ArtistAdapter() 时，它会起作用。

我在使用 Dagger2 进行注入(inject)时缺少什么？

附录:

mainFragment 将回调实现为点击监听器:

interface ArtistClickCallback {
    fun onClick(artist: LastFmArtist, poster : ImageView)
}

和:

class MainFragment : DaggerFragment(), ArtistClickCallback

这是 fragment 模块:

@Module
class MainFragmentModule {

    @Provides
    fun provideArtistAdapter(mainFragment: MainFragment) = ArtistAdapter(mainFragment)

}

但是当我从 Fragment 构造函数中删除 @Inject 时出现以下异常:

error: [Dagger/MissingBinding] com.sample.android.lastfm.ui.main.MainFragment cannot be provided without an @Inject constructor or an @Provides-annotated method. This type supports members injection but cannot be implicitly provided.
public abstract interface AppComponent extends dagger.android.AndroidInjector<com.sample.android.lastfm.LastFmApp> {
                ^
  A binding with matching key exists in component: com.sample.android.lastfm.ui.main.MainModule_MainFragment$app_debug.MainFragmentSubcomponent
      com.sample.android.lastfm.ui.main.MainFragment is injected at
          com.sample.android.lastfm.ui.main.MainActivity.mainFragment
      com.sample.android.lastfm.ui.main.MainActivity is injected at
          dagger.android.AndroidInjector.inject(T) [com.sample.android.lastfm.di.AppComponent → com.sample.android.lastfm.di.ActivityBindingModule_MainActivity$app_debug.MainActivitySubcomponent]

Answer 1

从 Fragment 构造函数中删除 @Inject 并为 fragment 提供适配器或在适配器中使用注入(inject)构造函数

@Module
abstract class MainModule {
    @FragmentScoped
    @ContributesAndroidInjector(modules = [MyAwesomeFragmentModule::class])
    internal abstract fun mainFragment(): MainFragment

} 

-

@Module
class MyAwesomeFragmentModule {

    @Provides
    fun provideArtistAdapter() = ArtistAdapter()

}