MasterActivity.java

public class MasterActivity extends AppCompatActivity {

    private MainViewModel viewModel;
  
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        viewModel = ViewModelProviders.of(this).get(MainViewModel.class);
        viewModel.load(savedInstanceState);
    }
  
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        viewModel.onSaveInstanceState(outState);
    }
}