Cannot create an instance of class ViewModel

Question

I am trying to write a sample app using Android architecture components and but even after trying for days I could not get it to work. It gives me the above exception.

Answer 1

I had this problem following google's roomdb CodeLab. Solution was changing the following.

Edited

Add the following Build dependencies to Gradle file (as of 2/22/2020)

implementation 'androidx.fragment:fragment:1.2.2'
implementation 'androidx.lifecycle:lifecycle-process:2.2.0'
implementation 'androidx.lifecycle:lifecycle-service:2.2.0'
implementation 'androidx.lifecycle:lifecycle-viewmodel-savedstate:2.2.0'
annotationProcessor 'androidx.lifecycle:lifecycle-compiler:2.2.0'

Imports within the fragment

import androidx.lifecycle.ViewModelProvider;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;

Creating the viewModel. Add one of the following methods.

Note: I'v seen this done many ways. I believe the correct way is using getDefaultViewModelProviderFactory(). But I have been using requireActivity().

 new ViewModelProvider(requireActivity(),getDefaultViewModelProviderFactory()).get(YourViewModel.class);

|

 new ViewModelProvider(requireActivity()).get(YourViewModel.class);

          

ViewModelProvider Docs

Deprecated

implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0-rc01'
annotationProcessor 'androidx.lifecycle:lifecycle-compiler:2.2.0-rc01'