What is ChangeNotifier in Flutter?
Why Interviewers Ask This
Mid-level Flutter roles require deep understanding of this topic. Interviewers ask this to separate candidates who truly understand the mechanics from those who only know surface-level concepts.
Answer
ChangeNotifier is a simple class from the Flutter foundation that provides a notification mechanism. You extend it in your state model class, and call notifyListeners() whenever the state changes. Widgets that are watching this notifier (via Provider's context.watch() or Consumer) will automatically rebuild. It is the backbone of Provider-based state management. For more scalable alternatives, Riverpod's NotifierProvider and BLoC are commonly used.
Pro Tip
Back up your answer with a specific project or situation. Saying 'In my last Flutter project, I used this when...' immediately makes your answer more credible and memorable.
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