Flutter notifyListeners

ChangeNotifier is a simple class included in the Flutter SDK which provides change notification to its listeners . In other words, if something is a ChangeNotifier , you can subscribe to its changes. (It is a form of Observable, for those familiar with the term.)

Listening to a change notifier is done by registering a callback, which is called when notifyListeners is invoked . That description felt a bit esoteric, so let’s just look at a quick ChangeNotifier example without Provider.

The ChangeNotifierProvider works as a provider-wrapper class that creates a ChangeNotifier and automatically disposes it when ChangeNotifierProvider is removed from the widget tree . By the way, create must not be null.