Kotliin Dagger Field Injection in ViewModel Throws Dagger/Binding Exception

Question

I have followed this tutorial in order to do DI in my viewmodels. But I currently am stuck.

I have created a ViewModelFactory for my viewmodel which is as follows:

Answer 1

The error message indicates that the following code is wrong:

fun providesHomeViewModelFactory(providerMap: Map<Class<out ViewModel>, Provider<ViewModel>>): HomeViewModelFactory {
    return HomeViewModelFactory(providerMap)
}

It should be

fun providesHomeViewModelFactory(providerMap: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>): HomeViewModelFactory {
    return HomeViewModelFactory(providerMap)
}

It is because the signature of Map interface is Map<K, out V>, that means the Map<..., Provider<ViewModel>> will be compiled to Map<..., ? extends Provider<ViewModel>> Java code, so you are asking dagger for latter one but it only has former one in its object graph, then the compiler throws you the error.