ChangeNotifier State Management in Flutter: The Lightweight Approach

Not every app needs Riverpod or Bloc. For local, simple state — a form’s dirty flag, a theme toggle, a shopping cart — ChangeNotifier from package:flutter/foundation.dart is enough. This follows the cited architecture guidance: a plain class extends ChangeNotifier, mutates state, and calls notifyListeners() to rebuild listeners.

The notifier

import 'package:flutter/foundation.dart';

class Counter extends ChangeNotifier {
  int _count = 0;
  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }

  void reset() {
    _count = 0;
    notifyListeners();
  }
}

Expose private fields behind getters so external code can read but not accidentally replace the whole value.

Listening

Use AnimatedBuilder or ListenableBuilder to rebuild when the notifier fires:

ListenableBuilder(
  listenable: counter,
  builder: (context, _) => Text('${counter.count}'),
)

Scoping with InheritedWidget

For app-wide state, wrap the notifier in an InheritedNotifier once near the root:

class CounterScope extends InheritedNotifier<Counter> {
  const CounterScope({super.key, required Counter counter, required super.child})
      : super(notifier: counter);

  static Counter of(BuildContext context) =>
      context.dependOnInheritedWidgetOfExactType<CounterScope>()!.notifier!;
}

Then read it anywhere below: CounterScope.of(context).increment().

Disposing

If your notifier owns resources (controllers, subscriptions), override dispose and cancel them — and make sure you don’t call notifyListeners() after disposal, which throws an assertion in debug mode.

Takeaway: ChangeNotifier plus notifyListeners() covers a surprising amount of real-world state — keep the state private behind getters, listen with ListenableBuilder, scope it with InheritedNotifier, and dispose resources properly.