The box "name" is already open and of type Box<dynamic>

The error is The box "todo_box" is already open and of type Box.

The relevant error-causing widget was: MyHomePage MyHomePage:file:///D:/Flutter_app/alimi_final/lib/schedule.dart:27:13 When the exception was thrown, this was the stack:

I have no idea about this error.

my code

main.dart

import 'package:hive/hive.dart';
import 'dart:io';
import 'package:path_provider/path_provider.dart';

import 'package:work_a/map.dart';
import 'package:work_a/schedule.dart';

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:work_a/boxes.dart';
import 'package:work_a/model/todo.dart';
import 'package:work_a/screens/list_screen.dart';
import 'package:hive_flutter/hive_flutter.dart';

//const bool kIsWeb = identical(0, 0.0);

//Future<Box> openHiveBox(todo_box) async {
  //if (!kIsWeb && !Hive.isBoxOpen(todo_box))
    //Hive.init((await getApplicationDocumentsDirectory()).path);

  //return await Hive.openBox(todo_box);
//}

Future<void> main() async{

  WidgetsFlutterBinding.ensureInitialized();
  final appDocumentDirectory = await getApplicationDocumentsDirectory();
  Hive.init(appDocumentDirectory.path);

  await Hive.initFlutter();
  Hive.registerAdapter(TodoAdapter());

  await Hive.openBox('todo_box');

  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  State<MyApp> createState() => _alimihomeState();
}

class _alimihomeState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'allimi',
      theme: ThemeData(primaryColor: Colors.blue),
      home: MyAppBar(),
      debugShowCheckedModeBanner: false,
    );
  }
}

class MyAppBar extends StatelessWidget {
  const MyAppBar({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('알리미'),
        backgroundColor: Color.fromRGBO(31, 39, 76, 1.0),
        centerTitle: true,
        elevation: 0.0,
      ),
      drawer: Drawer(
        child: ListView(
          children: [
            UserAccountsDrawerHeader(
              currentAccountPicture: CircleAvatar(
                backgroundImage: AssetImage('images/userimage.jpg'),
              ),
              accountName: Text('한동대생'),
              accountEmail: Text('00000000@handong.ac.kr'),
              decoration: BoxDecoration(
                color: Color.fromRGBO(31, 39, 76, 1.0),
                borderRadius: BorderRadius.only(
                  bottomLeft: Radius.circular(30.0),
                  bottomRight: Radius.circular(30.0),
                ),
              ),
            ),
            ListTile(
              leading: Icon(
                Icons.circle,
                color: Colors.black,
                size: 10.0,
              ),
              visualDensity: VisualDensity(vertical: -3),
              horizontalTitleGap: 1.0,
              title: Text('내 스케줄'),
              onTap: (){
                Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => schedule()),
                );
              },
            ),
            SizedBox(
              height: 5.0,
            ),
            ListTile(
              leading: Icon(
                Icons.circle,
                color: Colors.black,
                size: 10.0,
              ),
              visualDensity: VisualDensity(vertical: -3),
              horizontalTitleGap: 1.0,
              title: Text('지도 보기'),
              onTap: (){
                Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => MyMap()),
                );
              },
            ),
            SizedBox(
              height: 5.0,
            ),
            ListTile(
              leading: Icon(
                Icons.circle,
                color: Colors.black,
                size: 10.0,
              ),
              visualDensity: VisualDensity(vertical: -3),
              horizontalTitleGap: 1.0,
              title: Text('설정'),
              onTap: (){},
            ),
            SizedBox(
              height: 295.0,
            ),
          ],
        ),
      ),
      body: Center(
        child: Column(
          children: [
            SizedBox(
              height: 70.0,
            ),
            CircleAvatar(
              radius: 90.0,
              backgroundColor: Colors.white,
              backgroundImage: AssetImage('images/logoimage.jpg'),
            ),
            SizedBox(
              height: 30.0,
            ),
            Text(
              '한동 알리미',
              style: TextStyle(
                fontSize: 30.0,
                fontWeight: FontWeight.bold,
              ),
            ),
            SizedBox(
              height: 210.0,
            ),
            Text(
              'DADAEGEEDEUL',
              style: TextStyle(
                fontSize: 10.0,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

schedule.dart

import 'package:hive/hive.dart';
import 'package:work_a/boxes.dart';
import 'package:work_a/model/todo.dart';
import 'package:work_a/screens/list_screen.dart';
import 'package:hive_flutter/hive_flutter.dart';

// void main() => runApp(MyApp());
//void main() async {
  ////   hive initialization
  //await Hive.initFlutter();
  //Hive.registerAdapter(TodoAdapter());
  ////await Hive.openBox<Todo>(HiveBoxes.todo);
//}

class schedule extends StatelessWidget {
  const schedule({Key? key}) : super(key: key);
  static final String title = 'Hive Tutorial';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
          primarySwatch: Colors.blue
      ),
      home: MyHomePage(
        title: '스케줄',
      ),
    );
  }
}

list_screen.dart

import 'package:hive/hive.dart';
import 'package:work_a/boxes.dart';
import 'package:work_a/model/todo.dart';
import 'package:work_a/screens/add_todo_Screen.dart';
import 'package:hive_flutter/hive_flutter.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Todo Hive Example'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  @override
  void dispose() async {
    Hive.close();
    super.dispose();
    //await Hive.openBox<Todo>(HiveBoxes.todo);
    //await Hive.openBox<dynamic>('todo_box');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Color.fromRGBO(31, 39, 76, 1.0),
        title: Text(widget.title),
      ),
      body: ValueListenableBuilder(
          valueListenable: Hive.box<Todo>(HiveBoxes.todo).listenable(),
          builder: (context, Box<Todo> box, _) {
            if (box.values.isEmpty)
              return Center(
                child: Text("리스트가 비었습니다"),
              );

            return ListView.builder(
              itemCount: box.values.length,
              itemBuilder: (context, index) {
                Todo? res = box.getAt(index);
                return Dismissible(
                  background: Container(color: Colors.red),
                  key: UniqueKey(),
                  onDismissed: (direction) {
                    res!.delete();
                  },
                  child: ListTile(
                      title: Text(res!.title),
                      subtitle: Text(res.description),
                      onTap: () {}),
                );
              },
            );
          }),
      floatingActionButton: FloatingActionButton(
        tooltip: 'Add todo',
        child: Icon(Icons.add),
        backgroundColor: Color.fromRGBO(31, 39, 76, 1.0),
        onPressed: () => Navigator.of(context).push(
          MaterialPageRoute(
            builder: (context) => AddTodoScreen(),
          ),
        ),
      ),
    );
  }
}

add_todo_screen.dart

import 'package:hive/hive.dart';
import 'package:work_a/boxes.dart';
import 'package:work_a/model/todo.dart';

class AddTodoScreen extends StatefulWidget {
  AddTodoScreen({Key? key}) : super(key: key);

  @override
  _AddTodoScreenState createState() => _AddTodoScreenState();
}

class _AddTodoScreenState extends State<AddTodoScreen> {
  //void main() async {
  //  await Hive.openBox<Todo>(HiveBoxes.todo);
  //}
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  late String title;
  late String description;
  validated() {
    if (_formKey.currentState != null && _formKey.currentState!.validate()) {
      _onFormSubmit();
      print("Form Validated");
    } else {
      print("Form Not Validated");
      return;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Color.fromRGBO(31, 39, 76, 1.0),
        title: Text('스케줄 추가'),
      ),
      body: SafeArea(
        child: Form(
          key: _formKey,
          child: Padding(
            padding: EdgeInsets.all(8.0),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                TextFormField(
                  autofocus: true,
                  initialValue: '',
                  decoration: InputDecoration(
                      labelText: '스케줄'
                  ),
                  onChanged: (value) {
                    setState(() {
                      title = value;
                    });
                  },
                  validator: (String? value) {
                    if (value == null || value.trim().length == 0) {
                      return "required";
                    }
                    return null;
                  },
                ),
                TextFormField(
                  initialValue: '',
                  decoration: const InputDecoration(
                    labelText: '메모',
                  ),
                  onChanged: (value) {
                    setState(() {
                      description = value;
                    });
                  },
                  validator: (String? value) {
                    if (value == null || value.trim().length == 0) {
                      return "required";
                    }
                    return null;
                  },
                ),
                ElevatedButton(
                  style: ElevatedButton.styleFrom(
                    primary:Color.fromRGBO(31, 39, 76, 1.0),
                  ),
                  onPressed: () {
                    validated();
                  },
                  child: Text('추가'),
                )
              ],
            ),
          ),
        ),
      ),
    );
  }

  void _onFormSubmit() {
    Box<Todo> contactsBox = Hive.box<Todo>(HiveBoxes.todo);
    contactsBox.add(Todo(title: title, description: description));
    Navigator.of(context).pop();
  }
}

ui_test.dart

import 'package:work_a/screens/add_todo_Screen.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Todo Hive Example'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Color.fromRGBO(31, 39, 76, 1.0),
        centerTitle: true,
        title: Text(widget.title),
      ),
      body: Container(
        child: ListView.builder(
          itemBuilder: (context, index) {
            return Dismissible(
              background: Container(color: Colors.red),
              key: UniqueKey(),
              onDismissed: (direction) {},
              child: ListTile(
                  title: Text('Title'),
                  subtitle: Text('Description'),
                  onTap: () {}),
            );
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        tooltip: 'Add todo',
        child: Icon(Icons.add),
        onPressed: () => Navigator.of(context).push(
          MaterialPageRoute(
            builder: (context) => AddTodoScreen(),
          ),
        ),
      ),
    );
  }
}

boxs.dart

class HiveBoxes {
  static String todo = 'todo_box';
} 

todo.dart

import 'package:hive/hive.dart';
part 'todo.g.dart';

@HiveType(typeId: 0)
class Todo extends HiveObject {
  @HiveField(0)
  String? id;

  @HiveField(1)
  String title;

  @HiveField(2)
  String description;

  Todo({required this.title, required this.description});
}

and

todo.g.dart