android - 在 Android 中使用 Hilt 后无法创建 View 模型实例

Question

这是我的AllFilesListViewModel类(class)。

class AllFilesListViewModel @ViewModelInject constructor(
    private val pdfItemRepository: PdfItemRepository):ViewModel() {

}

这里是 PdfItemRepository类(class)。

@Singleton
class PdfItemRepository @Inject constructor(private val pdfItemDao: PdfItemDao){

}

对于 pdfItemDao .我创建了一个名为 DatabaseModule 的模块.下面是代码 -

@Module
@InstallIn(ApplicationComponent::class)
object DatabaseModule {

    @Provides
    fun provideDatabase(@ApplicationContext context: Context):AppDatabase{
        return AppDatabase.getDataBase(context)
    }

    @Provides
    fun providePdfItemDao(database:AppDatabase):PdfItemDao{
        return database.pdfItemDao()
    }
}

这是 fragment 类AllFilesFragment.kt我在哪里使用 viewModel。

@AndroidEntryPoint
class AllFilesFragment:Fragment(){

    private lateinit var binding:AllFilesFragmentBinding
    private val viewModel by viewModels<AllFilesListViewModel>()


    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = AllFilesFragmentBinding.inflate(inflater,container,false)
        context?: return binding.root
        initThings()
        subscribeUi()
        return binding.root
    }
}

这里是 logcat文件。

06-19 19:22:20.203 23753-23753/com.emptysheet.pdfreader_autoscroll E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.emptysheet.pdfreader_autoscroll, PID: 23753
    java.lang.RuntimeException: Cannot create an instance of class com.emptysheet.pdfreader_autoscroll.homeScreen.viewModel.AllFilesListViewModel
        at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:221)
        at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
        at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:106)
        at androidx.hilt.lifecycle.HiltViewModelFactory.create(HiltViewModelFactory.java:69)
        at androidx.lifecycle.AbstractSavedStateViewModelFactory.create(AbstractSavedStateViewModelFactory.java:69)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
        at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:54)
        at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:41)
        at com.emptysheet.pdfreader_autoscroll.homeScreen.AllFilesFragment.getViewModel(AllFilesFragment.kt)
        at com.emptysheet.pdfreader_autoscroll.homeScreen.AllFilesFragment.subscribeUi(AllFilesFragment.kt:72)
        at com.emptysheet.pdfreader_autoscroll.homeScreen.AllFilesFragment.onCreateView(AllFilesFragment.kt:64)
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2698)
        at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:320)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356)
        at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1434)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:442)
        at androidx.fragment.app.FragmentManager.executeOps(FragmentManager.java:2169)
        at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1992)
        at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1947)
        at androidx.fragment.app.FragmentManager.execSingleAction(FragmentManager.java:1818)
        at androidx.fragment.app.BackStackRecord.commitNow(BackStackRecord.java:297)
        at androidx.viewpager2.adapter.FragmentStateAdapter.placeFragmentInViewHolder(FragmentStateAdapter.java:341)
        at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:276)
        at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:67)
        at androidx.recyclerview.widget.RecyclerView.dispatchChildAttached(RecyclerView.java:7556)
        at androidx.recyclerview.widget.RecyclerView$5.addView(RecyclerView.java:860)
        at androidx.recyclerview.widget.ChildHelper.addView(ChildHelper.java:107)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:8601)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:8559)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:8547)
        at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1641)
        at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
        at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:665)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
        at android.view.View.layout(View.java:15689)
        at android.view.ViewGroup.layout(ViewGroup.java:5048)
        at androidx.viewpager2.widget.ViewPager2.onLayout(ViewPager2.java:527)
        at android.view.View.layout(View.java:15689)
        at android.view.ViewGroup.layout(ViewGroup.java:5048)
        at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:148)
        at com.google.android.material.appbar.V

Answer 1

这发生在我使用 Hilt 时，那是因为我忘记添加 @AndroidEntryPoint fragment 类顶部的注释。
fragment 和宿主 Activity 都应使用此注释进行注释。