ChangeNotifierの実装（メインページ）

lib/main.dart

@@ -4,9 +4,9 @@ import 'package:provider/provider.dart';
 import 'package:chat_flutter/di.dart';
 import 'package:chat_flutter/ui/pages/add_friend.dart';
 import 'package:chat_flutter/ui/pages/create_group.dart';
-import 'package:chat_flutter/ui/pages/main.dart';
-import 'package:chat_flutter/ui/pages/profile_edit.dart';
-import 'package:chat_flutter/ui/pages/profile.dart';
+import 'package:chat_flutter/ui/pages/main/main.dart';
+import 'package:chat_flutter/ui/pages/main/profile/profile_edit.dart';
+import 'package:chat_flutter/ui/pages/main/profile/profile.dart';
 import 'package:chat_flutter/ui/pages/room.dart';
 import 'package:chat_flutter/ui/pages/sign_in.dart';
 import 'package:chat_flutter/ui/pages/sign_up.dart';

lib/ui/pages/main/home/home_controller.dart

@@ -0,0 +1,5 @@
+import 'package:flutter/material.dart';
+
+class HomeController with ChangeNotifier{
+
+}

lib/ui/pages/main.dart → lib/ui/pages/main/main.dart

@@ -1,26 +1,17 @@
 import 'package:chat_flutter/ui/molecules/home/app_bar.dart';
 import 'package:chat_flutter/ui/molecules/profile/app_bar.dart';
 import 'package:chat_flutter/ui/molecules/talk/app_bar.dart';
-import 'package:chat_flutter/ui/pages/home.dart';
-import 'package:chat_flutter/ui/pages/profile.dart';
-import 'package:chat_flutter/ui/pages/talk.dart';
+import 'package:chat_flutter/ui/pages/main/home/home.dart';
+import 'package:chat_flutter/ui/pages/main/main_controller.dart';
+import 'package:chat_flutter/ui/pages/main/profile/profile.dart';
+import 'package:chat_flutter/ui/pages/main/talk/talk.dart';
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
-class MainPage extends StatefulWidget {
-  @override
-  _MainPageState createState() => _MainPageState();
-}
-
-class _MainPageState extends State<MainPage> {
-  int _currentIndex = 0;
-  void changePage(int index) {
-    setState(
-      () => _currentIndex = index,
-    );
-  }
-
+class MainPage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
+    final _mainController = Provider.of<MainController>(context);
     final List appBarList = [
       HomePageAppBar(),
       TalkPageAppBar(),
@@ -40,20 +31,21 @@ class _MainPageState extends State<MainPage> {
     ];
 
     return Scaffold(
-      appBar: appBarList[_currentIndex],
-      backgroundColor: backgroundColor[_currentIndex],
-      bottomNavigationBar: bottomNavigation(),
-      body: pages[_currentIndex],
+      appBar: appBarList[_mainController.currentIndex],
+      backgroundColor: backgroundColor[_mainController.currentIndex],
+      bottomNavigationBar: bottomNavigation(context),
+      body: pages[_mainController.currentIndex],
     );
   }
 
-  Widget bottomNavigation() {
+  Widget bottomNavigation(BuildContext context) {
+    final _mainController = Provider.of<MainController>(context);
     return BottomNavigationBar(
       backgroundColor: Colors.white,
       type: BottomNavigationBarType.fixed,
       showSelectedLabels: false,
       showUnselectedLabels: false,
-      currentIndex: _currentIndex,
+      currentIndex: _mainController.currentIndex,
       items: [
         BottomNavigationBarItem(
           icon: Icon(
@@ -80,9 +72,9 @@ class _MainPageState extends State<MainPage> {
           ),
         ),
       ],
-      onTap: (index) => setState(
-        () => _currentIndex = index,
-      ),
+      onTap: (index){
+        _mainController.changePage(index);
+      }
     );
   }
 }

lib/ui/pages/main/main_controller.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/material.dart';
+
+class MainController with ChangeNotifier{
+  int currentIndex;
+  MainController(){
+    currentIndex = 0;
+  }
+
+  void changePage(int index){
+    currentIndex = index;
+    notifyListeners();
+  }
+}

lib/ui/pages/main/profile/profile_controller.dart

@@ -0,0 +1,5 @@
+import 'package:flutter/material.dart';
+
+class ProfileController with ChangeNotifier{
+
+}

lib/ui/pages/main/profile/profile_edit_controller.dart

@@ -0,0 +1,5 @@
+import 'package:flutter/material.dart';
+
+class ProfileEditController with ChangeNotifier{
+
+}

lib/ui/pages/main/talk/talk_controller.dart

@@ -0,0 +1,5 @@
+import 'package:flutter/material.dart';
+
+class TalkController with ChangeNotifier{
+
+}