java.lang.ClassCastException: com.eng.bt_eng_mobility.viewmodel.HomeViewModelFactory cannot be cast to androidx.lifecycle.ViewModel

Question

I am getting this error. I have created ViewModelFactory class inside same ViewModel class file. When Im trying to initialise the viewmodel I am getting this error.

//Code written in fragment class in onCreateView after binding code//
homeViewModelFactory = HomeViewModelFactory((requireActivity().application as Application).repository)
        homeViewModel = ViewModelProvider(this, homeViewModelFactory)
                .get(HomeViewModel::class.java)


//Viewmodelfactoryclass//
class HomeViewModelFactory(private val homeRepository: HomeRepository) : ViewModelProvider.Factory {
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        if (modelClass.isAssignableFrom(HomeViewModel::class.java)) {
            return HomeViewModelFactory(homeRepository) as T
        }
        throw IllegalArgumentException("Unknown ViewModel class")
    }
}

yes right. But its giving class cast exception like I stated above — Josss, Mar 27 '21 at 19:03
The `create` method should create an instance of your view model, not another factory, otherwise we're in an infinite loop of factory creating. — Henry Twist, Mar 27 '21 at 19:04
I would recommend taking a look at the documentation here: https://developer.android.com/reference/androidx/lifecycle/ViewModelProvider.Factory#create(java.lang.Class%3CT%3E) — Henry Twist, Mar 27 '21 at 19:05

score 4 · Accepted Answer · answered Mar 27 '21 at 19:35

The job of the ViewModelProvider.Factory is to create instances of your ViewModel class. At the moment all you're doing is returning a new instance of your factory.

Instead your return statement should probably be something like this:

return HomeViewModel(homeRepository) as T

This article covers the basics of a ViewModel in more detail.

java.lang.ClassCastException: com.eng.bt_eng_mobility.viewmodel.HomeViewModelFactory cannot be cast to androidx.lifecycle.ViewModel

1 Answers1