flutter_provider_demo

lib/pages/selector_page.dart

@@ -0,0 +1,101 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+class SelectorPage extends StatelessWidget {
+  const SelectorPage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider(
+      create: (_) => ComplexState(),
+      child: Scaffold(
+        appBar: AppBar(
+          title: const Text('Selector Example'),
+        ),
+        body: const Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: [
+              CountSelector(),
+              NameSelector(),
+              UpdateButtons(),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class ComplexState extends ChangeNotifier {
+  int _count = 0;
+  String _name = "John";
+
+  int get count => _count;
+  String get name => _name;
+
+  void incrementCount() {
+    _count++;
+    notifyListeners();
+  }
+
+  void changeName() {
+    _name = _name == "John" ? "Jane" : "John";
+    notifyListeners();
+  }
+}
+
+class CountSelector extends StatelessWidget {
+  const CountSelector({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Selector<ComplexState, int>(
+      selector: (_, state) => state.count,
+      builder: (context, count, child) {
+        print('Count rebuild');
+        return Text('Count: $count');
+      },
+    );
+  }
+}
+
+class NameSelector extends StatelessWidget {
+  const NameSelector({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Selector<ComplexState, String>(
+      selector: (_, state) => state.name,
+      builder: (context, name, child) {
+        print('Name rebuild');
+        return Text('Name: $name');
+      },
+    );
+  }
+}
+
+class UpdateButtons extends StatelessWidget {
+  const UpdateButtons({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      children: [
+        ElevatedButton(
+          onPressed: () {
+            context.read<ComplexState>().incrementCount();
+            context.read<ComplexState>().changeName();
+          },
+          child: const Text('Increment Count'),
+        ),
+        ElevatedButton(
+          onPressed: () {
+            context.read<ComplexState>().changeName();
+          },
+          child: const Text('Change Name'),
+        ),
+      ],
+    );
+  }
+}