Manually clearing an Android ViewModel?

Question

Edit: This question is a bit out of date now that Google has given us the ability to scope ViewModel to navigation graphs. The better approach (rather

Answer 1

I found a simple and fairly elegant way to deal with this issue. The trick is to use a DummyViewModel and model key.

The code works because AndroidX checks the class type of the model on get(). If it doesn't match it creates a new ViewModel using the current ViewModelProvider.Factory.

public class MyActivity extends AppCompatActivity {
    private static final String KEY_MY_MODEL = "model";

    void clearMyViewModel() {
        new ViewModelProvider(this, new ViewModelProvider.NewInstanceFactory()).
            .get(KEY_MY_MODEL, DummyViewModel.class);
    }

    MyViewModel getMyViewModel() {
        return new ViewModelProvider(this, new ViewModelProvider.AndroidViewModelFactory(getApplication()).
            .get(KEY_MY_MODEL, MyViewModel.class);
    }

    static class DummyViewModel extends ViewModel {
        //Intentionally blank
    }
}