33.5 Associating the Fragment with the View Model

Clearly, there needs to be some way for the fragment to obtain a reference to the ViewModel in order to be able to access the model and observe data changes. A Fragment or Activity maintains references to the ViewModels on which it relies for data using an instance of the ViewModelProvider class.

A ViewModelProvider instance is created using the ViewModelProvider class from within the Fragment. When called, the class initializer is passed a reference to the current Fragment or Activity and returns a ViewModelProvider instance as follows:

ViewModelProvider viewModelProvider = new ViewModelProvider(this);

Once the ViewModelProvider instance has been created, the get() method can be called on that instance passing through the class of specific ViewModel that is required. The provider will then either create a new instance of that ViewModel class, or return an existing instance:

ViewModel viewModel = viewModelProvider.get(MainViewModel...