问题
Here is my AllFilesListViewModel class.
class AllFilesListViewModel @ViewModelInject constructor(
private val pdfItemRepository: PdfItemRepository):ViewModel() {
}
Here is PdfItemRepository class.
@Singleton
class PdfItemRepository @Inject constructor(private val pdfItemDao: PdfItemDao){
}
For pdfItemDao. I created a module named DatabaseModule. Below is the code -
@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()
}
}
Here is the fragment class AllFilesFragment.kt where I am using 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
}
}
Here is logcat file.
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
回答1:
This got solved after I used kapt 'androidx.hilt:hilt-compiler:1.0.0-alpha01' in app's build.gradle. I had already added kapt "com.google.dagger:hilt-android-compiler:2.28-alpha". I still didn't understand the difference between two BTW. If anyone knows. Please explain it to me.
回答2:
This is caused by a version mismatch between AndroidX Lifecycle, AndroidX Core, AndroidX Activity and AndroidX Fragment.
Hilt only works if getDefaultViewModelProviderFactory can be overridden.
This is only true if that method actually exists, which it doesn't if your dependencies are out of date. Namely, your androidx.fragment is lower than 1.2.0, and your androidx.activity is lower than 1.1.0.
Use this and it'll work:
implementation "androidx.appcompat:appcompat:1.1.0"
implementation "androidx.fragment:fragment-ktx:1.2.5"
implementation "androidx.core:core-ktx:1.3.0"
implementation "androidx.activity:activity:1.1.0"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.2.0"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.2.0"
implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.2.0"
But currently, this is what makes it work for me:
implementation 'com.google.dagger:dagger:2.28'
kapt 'com.google.dagger:dagger-compiler:2.28'
// hilt
implementation 'com.google.dagger:hilt-android:2.28-alpha'
kapt 'com.google.dagger:hilt-android-compiler:2.28-alpha'
kaptAndroidTest 'com.google.dagger:hilt-android-compiler:2.28-alpha'
kaptTest 'com.google.dagger:hilt-android-compiler:2.28-alpha'
implementation 'androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha01'
kapt 'androidx.hilt:hilt-compiler:1.0.0-alpha01'
Along with
apply plugin: 'dagger.hilt.android.plugin'
And
classpath 'com.google.dagger:hilt-android-gradle-plugin:2.28-alpha'
回答3:
i have this issue i dont know what problem is or how to solve it, everything was fine with dagger swapped to hilt and now i cant create android view models, i get
Cannot create an instance of class com.sealstudios.simpleaac.shared.view_models.UserViewModel
where UserViewModel extends AndroidViewModel
none of the solutions here have helped
回答4:
I faced this issue before and I have fixed it by passing SavedStateHandle to the main constructor of the view model.
class AuthViewModel @ViewModelInject constructor(@Assisted private val savedState: SavedStateHandle) : ViewModel()
来源：https://stackoverflow.com/questions/62471849/cannot-create-instance-of-viewmodel-after-using-hilt-in-android