Dagger/MissingBinding java.util.Map,Provider

问题:

This is how I'm trying to provide my ViewModelFactory:

@Suppress("UNCHECKED_CAST")
@Singleton
class ViewModelFactory @Inject constructor(
    private val viewModels: MutableMap<Class<out ViewModel>, Provider<ViewModel>>
) : ViewModelProvider.Factory {

    override fun <T : ViewModel?> create(modelClass: Class<T>): T = viewModels[modelClass]?.get() as T
}

@Target(AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER)
@kotlin.annotation.Retention(AnnotationRetention.RUNTIME)
@MapKey
annotation class ViewModelKey(val value: KClass<out ViewModel>)

And this is how I'm binding the ViewModelFactory:

@Suppress("unused")
@Module
abstract class ViewModelModule  {
    @Binds
    internal abstract fun bindViewModelFactory(factory: ViewModelFactory): ViewModelProvider.Factory

    @Binds
    @IntoMap
    @ViewModelKey(MainViewModel::class)
    internal abstract fun mainViewModel(viewModel: MainViewModel): ViewModel
}

I'm receiving the following error during build:

di/Injector.java:9: error: [Dagger/MissingBinding] java.util.Map<java.lang.Class<? extends androidx.lifecycle.ViewModel>,javax.inject.Provider<androidx.lifecycle.ViewModel>> cannot be provided without an @Provides-annotated method.

From my Activity I'm trying to receive the ViewModelFactory this way:

@Inject
lateinit var viewModelFactory: ViewModelProvider.Factory

回答1:

After digging a little bit more I found the issue. It's completely un-related to the code I'm using. It regards Kotlin 1.3.30.

Here some more information about it.

Downgrading to Kotlin 1.3.21 resolved the problem.

回答2:

I faced the same issue recently. Version Kotlin:1.3.40 Dagger:2.23.2 I tried following the solutions mentioned in this post and here

but none seemed to work. The annotation processor of Dagger is not playing well with KAPT and for the same reason, the builds are failing. This is also updated on Kotlin issue too.

For me, converting both the ViewModelKey and ViewModelFactory to java worked. For Dagger, the tracking issue can be found here.

Update Adding @JvmSuppressWildcards fixed the issue. Code looks like this:

private val providers: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>

回答3:

 No need to Downgrade the Kotlin version. As the day of Post my Kotlin version
 is : '1.3.40'

 Use dagger dependency in build.gradle

 apply plugin: 'kotlin-kapt'

 //Dagger dependencies
implementation 'com.google.dagger:dagger:2.22.1'
kapt 'com.google.dagger:dagger-compiler:2.22.1'

implementation 'com.google.dagger:dagger-android:2.22'
implementation 'com.google.dagger:dagger-android-support:2.22' // if you use the support libraries
kapt 'com.google.dagger:dagger-android-processor:2.22'


And for Java use the following dagger dependency

 //Dagger dependencies
implementation 'com.google.dagger:dagger:2.22.1'
annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'

implementation 'com.google.dagger:dagger-android:2.22'
implementation 'com.google.dagger:dagger-android-support:2.22' // if you use the support libraries
annotationProcessor 'com.google.dagger:dagger-android-processor:2.22'