How to get an Instance of ViewModel in activity in 2020/21?

Question

I am new to the mvvm pattern. I created a ViewModel for the main activity. Now I want to get an instance of the ViewModel in the main activity.

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Answer 1

You can use a ViewModelFactory:

val viewModelFactory = VMFactory(requireActivity().application)
viewModel= ViewModelProvider(requireActivity(),viewModelFactory).get(MainViewModel::class.java)

VMFactory code:

class VMFactory(application: Application) : ViewModelProvider.NewInstanceFactory() {

    val _application: Application=application

    @NonNull
    override fun  create(@NonNull modelClass: Class): T {
            return  MainViewModel(_application) as T
    }
}

Please note that here my MainViewModel extends AndroidViewModel and hence requires application as the input parameter.