update

.config/Code/User/History/-2e064889/6otU.dart

@@ -0,0 +1,77 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+void main(){
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget{
+  const MyApp({super.key});
+  
+  @override
+  Widget build(BuildContext context){
+    return ChangeNotifierProvider(
+      create: (context) => MyAppState(),
+      child: MaterialApp(
+        title: 'First App',
+        theme: ThemeData(
+          useMaterial3: true,
+          colorScheme: ColorScheme.fromSeed(seedColor: Colors.green)
+        ),
+        home: const MyHomePage(),
+      ),
+    );
+  }
+}
+
+class MyAppState extends ChangeNotifier{
+  var counter = 0;
+
+  void increment(){
+    counter++;
+    notifyListeners();
+  }
+}
+
+class MyHomePage extends StatefulWidget{
+  const MyHomePage({super.key});
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  @override
+  Widget build(BuildContext context){
+    var appState = context.watch<MyAppState>();
+    var sCount = appState.counter.toString();
+
+    return Scaffold(
+      body: Row(
+        children: [
+          SafeArea(
+            child: NavigationRail(
+              destinations: [
+                NavigationRailDestination(
+                  icon: Icon(Icons.home), label: Text('Home')
+                  )
+              ], selectedIndex: 0)
+          ),
+          Center(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Text('count: $sCount'),
+                ElevatedButton(
+                  onPressed: () => appState.increment(),
+                  child: const Text('Increment')
+                ),
+              ],
+            ),
+          ),
+
+        ],
+      )
+    );
+  }
+}