Why can the project create an instance of class ViewModel with constructor argument without a factory

Question

I have read the artical.

When you are initialising the ViewModel through ViewModelProviders without a factory, this means that you can only instantiate a ViewModel which has no constructor arguments.

The following code is from the project android-room-with-a-view

Why can the project create an instance of class ViewModel with constructor argument without a factory in Kotlin?

Code

wordViewModel = ViewModelProvider(this).get(WordViewModel::class.java)


class WordViewModel(application: Application) : AndroidViewModel(application) {

   ...
}

score 3 · Accepted Answer · answered Jul 29 '20 at 01:26

That answer has always been wrong. ViewModelProviders.of(this) has always used at least AndroidViewModelFactory, which supports the AndroidViewModel class which allows automatically making an Application class available as a constructor parameter.

Additionally, when using Fragment 1.2.0 or higher, the default factory has been updated to SavedStateViewModelFactory to also support using SavedStateHandle as a constructor parameter as per the Saved State module with ViewModel guide.

Why can the project create an instance of class ViewModel with constructor argument without a factory

1 Answers1