init project

lib/main.dart

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+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_provider_example/provider.dart';
+import 'package:provider/provider.dart';
+
+void main() {
+  final provders = [
+    ChangeNotifierProvider(
+      create: (context) => MyProvider(),
+    ),
+  ];
+
+  runApp(MultiProvider(providers: provders, child: const MyApp()));
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Provider',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: const MyHomePage(title: 'Flutter Provier Home Page'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key? key, required this.title}) : super(key: key);
+  final String title;
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  MyProvider? _provider;
+  int _counter = 0;
+
+  @override
+  void initState() {
+    if (kDebugMode) {
+      print('initState');
+    }
+
+    super.initState();
+
+    // Load the provider
+    _provider = Provider.of<MyProvider>(context, listen: false);
+  }
+
+  @override
+  void didChangeDependencies() {
+    if (kDebugMode) {
+      print('didChangeDependencies');
+    }
+    super.didChangeDependencies();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (kDebugMode) {
+      print("_MyHomePageState.build()");
+    }
+
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: Center(
+        child: ListView.builder(
+          itemBuilder: (context, index) {
+            final person = _provider!.people[index];
+            return ListTile(
+              title: Text('Name: ${person.name}'),
+              subtitle: Text('Age: ${person.age}'),
+            );
+          },
+          itemCount: _provider?.people.length ?? 0,
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: () {
+          if (_counter % 2 == 0) {
+            _provider!.addPerson(Person('World', 30));
+          } else {
+            _provider!.removeLastPerson();
+          }
+          setState(() {
+            _counter++;
+          });
+        },
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ),
+    );
+  }
+}

lib/provider.dart

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+import 'package:flutter/foundation.dart';
+
+class Person {
+  String name;
+  int age;
+
+  Person(this.name, this.age);
+}
+
+class MyProvider with ChangeNotifier {
+  final List<Person> _people = [
+    Person('John', 30),
+    Person('Jane', 25),
+    Person('Jack', 20),
+    Person('Chea', 40),
+  ];
+
+  List<Person> get people => _people;
+
+  void addPerson(Person person) {
+    _people.add(person);
+    notifyListeners();
+  }
+
+  void removePerson(Person person) {
+    _people.remove(person);
+    notifyListeners();
+  }
+
+  void removeLastPerson() {
+    _people.removeLast();
+    notifyListeners();
+  }
+}