任何人都可以给我解决这个错误的方法吗？ 我不知道错误何时发生，也不知道导致此问题的代码部分是什么
这是我运行程序时显示的错误
═══════ Exception caught by widgets library ═══════════════════════════════════
The following _TypeError was thrown building MyApp(dirty):
type '_Type' is not a subtype of type 'BuildContext'
The relevant error-causing widget was
MyApp
package:my_first_app/main.dart:15
When the exception was thrown, this was the stack
#0 TasksCubit.get
package:my_first_app/…/mycubitclasses/taskscubit_class.dart:14
#1 new HomeLayout
package:my_first_app/layout/homelayout.dart:29
#2 MyApp.build
package:my_first_app/main.dart:24
#3 StatelessElement.build
package:flutter/…/widgets/framework.dart:4876
#4 ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4806
#5 Element.rebuild
package:flutter/…/widgets/framework.dart:4529
#6 ComponentElement._firstBuild
package:flutter/…/widgets/framework.dart:4787
#7 ComponentElement.mount
package:flutter/…/widgets/framework.dart:4781
#8 Element.inflateWidget
package:flutter/…/widgets/framework.dart:3817
#9 Element.updateChild
package:flutter/…/widgets/framework.dart:3551
#10 RenderObjectToWidgetElement._rebuild
package:flutter/…/widgets/binding.dart:1202
#11 RenderObjectToWidgetElement.mount
package:flutter/…/widgets/binding.dart:1171
#12 RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure>
package:flutter/…/widgets/binding.dart:1119
#13 BuildOwner.buildScope
package:flutter/…/widgets/framework.dart:2597
#14 RenderObjectToWidgetAdapter.attachToRenderTree
package:flutter/…/widgets/binding.dart:1118
#15 WidgetsBinding.attachRootWidget
package:flutter/…/widgets/binding.dart:953
#16 WidgetsBinding.scheduleAttachRootWidget.<anonymous closure>
这是我的 main.dart 文件
import 'package:bloc/bloc.dart';
import 'package:flutter/material.dart';
import 'package:my_first_app/layout/homelayout.dart';
import 'package:my_first_app/moduls/login/login.dart';
import 'package:my_first_app/moduls/messanger/messangerscreen.dart';
import 'package:my_first_app/moduls/counter/counter_screen.dart';
import 'package:my_first_app/moduls/messanger/mydesign.dart';
import 'moduls/homescreen/HomeScreen.dart';
import 'moduls/counter/counter_screen.dart';
import 'moduls/bmiscreen/ibm_calculator.dart';
import 'shared/bloc_observ.dart';
void main() {
// Bloc.observer = MyBlocObserver();
return runApp(MyApp());
}
//=========================================================
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context)
{
return MaterialApp(
debugShowCheckedModeBanner: false ,
home: HomeLayout(),
);
}
}
我添加了肘类..也许当我添加它时出现问题
这是我的
HomeLayout// ignore_for_file: prefer_const_constructors
import 'dart:ffi';
import 'package:conditional_builder_null_safety/conditional_builder_null_safety.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:intl/intl.dart';
import 'package:my_first_app/moduls/archive_task_screen/archive_task.dart';
import 'package:my_first_app/moduls/done_task_screen/done_task.dart';
import 'package:my_first_app/moduls/new_task_screen/new_task.dart';
import 'dart:async';
import 'package:flutter/widgets.dart';
import 'package:my_first_app/shared/componants/componants.dart';
import 'package:my_first_app/shared/mycubitclasses/taskscubit_class.dart';
import 'package:my_first_app/shared/mycubitclasses/taskstates.dart';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';
import '../shared/componants/constants.dart';
class HomeLayout extends StatelessWidget
{
//======================variables===============================
var scaffoldkey = GlobalKey<ScaffoldState>();
var formkey = GlobalKey<FormState>();
var titleController = TextEditingController();
var timeController = TextEditingController();
var dateController = TextEditingController();
TasksCubit cubitt = TasksCubit.get(context);
// scaffold contain in this screen :
// 1. appBar 2. FAB floatingActionButton 3. body 4. bottomNavigationBar
//=================================================================
//=================================================================
@override
Widget build(BuildContext context)
{
return BlocProvider (
create: (context) {
return TasksCubit()..creatDataBase();
},
child: Scaffold(
key: scaffoldkey,
//========================app bar =================================
appBar: AppBar(
title: Text(
cubitt.titls[cubitt.currentindex],
),
),
//===========================body ======================================
body: BlocBuilder<TasksCubit,TasksStates>(
builder: (BuildContext context, TasksStates state)
{
if (state is InsertDataBase)
{
Navigator.pop(context);
}
return cubitt.screens[cubitt.currentindex];
}),
//===========================FAB======================================
floatingActionButton: FloatingActionButton(
onPressed: ()
{
if (cubitt. isBottomSheetShown)
{
cubitt.InserttTODataBase(
titel: titleController.text,
date: dateController.text,
time: timeController.text,
status: 'new',
).then((value) {
print( '*************************** Insert succesfully **************************');
cubitt.ChangeBottomState(false,Icons.edit);
});
}
else // if bottomsheet closed
{
scaffoldkey.currentState!.showBottomSheet(
(context) => Container(
padding: EdgeInsets.all(20.0),
color: Colors.grey[200],
child: Column(
mainAxisSize: MainAxisSize.min,
children:
[
DefoultFormField(
controller: titleController,
label: 'input title',
prefix: Icons.title,
type: TextInputType.text,
validate: ((String value) {}),
// validate: (String? value){
// if(value!.isEmpty)
// {
// return' must title not empty ';
// }
// return null ;
// },
),
SizedBox(
height: 5.0,
),
//////////////////////////////////////////////////////////////////////
DefoultFormField(
controller: timeController,
label: 'input time',
prefix: Icons.watch,
type: TextInputType.datetime,
validate: ((String value) {}),
// validate: (String? value){
// if(value!.isEmpty)
// {
// return' must time not empty ';
// }
// // return null ;
// },
ontap: () {
showTimePicker(
context: context,
initialTime: TimeOfDay.now(),
).then((value) {
return timeController.text =
value!.format(context);
});
},
),
///////////////////////////// formfied date /////////////////////////////////////////
SizedBox(
height: 5.0,
),
DefoultFormField(
controller: dateController,
label: 'input date',
prefix: Icons.calendar_today,
type: TextInputType.datetime,
validate: ((String value) {}),
// validate: (String value){
// if(value.isEmpty)
// return' must date not empty ';
// return null ;
// },
ontap: () {
showDatePicker(
context: context,
initialDate: DateTime.now(),
firstDate: DateTime.now(),
lastDate: DateTime.parse('2023-05-05'),
).then((value) {
return dateController.text =
DateFormat.yMMMd().format(value!);
});
},
),
//////////////////////////////////////////////////////////////////////
],
),
),
// if i closed the bottomSheet in my hand not in FAB will give error so i did this :
)
.closed .then((value)
{
cubitt.ChangeBottomState(false,Icons.edit);
}); // closed func
cubitt.ChangeBottomState(true,Icons.add);
}
},
child: Icon(
cubitt. fabicon,
),
),
//======================== BottomNavigationBar =========================================
bottomNavigationBar: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
elevation: 50.0,
currentIndex: cubitt.currentindex,
onTap: (index) {
cubitt.ChangeIndex(index);
},
backgroundColor: Colors.blue[200],
items:
[
BottomNavigationBarItem(
icon: Icon(
Icons.menu,
),
label: 'NEW TASK',
),
BottomNavigationBarItem(
icon: Icon(
Icons.done_all,
),
label: 'DONE TASK',
),
BottomNavigationBarItem(
icon: Icon(
Icons.archive,
),
label: 'ARCHIVE TASK',
),
],
),
),
);
}
//============================ finish scaffold =======================================
}
这是 TasksCubit 类
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:my_first_app/moduls/new_task_screen/new_task.dart';
import 'package:my_first_app/shared/mycubitclasses/taskstates.dart';
import 'package:sqflite/sqflite.dart';
import '../../moduls/archive_task_screen/archive_task.dart';
import '../../moduls/done_task_screen/done_task.dart';
class TasksCubit extends Cubit<TasksStates>
{
TasksCubit():super ( InitailTasksState());
static TasksCubit get(context)=>BlocProvider.of(context);
//////////////////////////////////////////////////////////////////////
int currentindex = 0;
List<Widget> screens = [
NewTask(),
DoneTask(),
ArchiveTask(),
];
List<String> titls = [
'new task',
'done task ',
'archive task',
];
void ChangeIndex (index)
{
currentindex =index;
emit(changBottomNavBar());
}
var isBottomSheetShown = false;
IconData fabicon = Icons.add;
void ChangeBottomState ( bool isShow ,IconData icon )
{
isBottomSheetShown=isShow;
fabicon=icon;
emit(changBottomSheet());
}
// **************************** DataBase ************************************
late Database Mydatabase;
List<Map> tasks =[];
void creatDataBase() {
openDatabase(
'todo.db',
version: 1,
onCreate: (db, version) {
print(
'************************** daataBase Created ****************************');
db .execute(
'CREATE TABLE tasks (id INTEGER PRIMARY KEY,titel TEXT,date TEXT,time TEXT,status TEXT)')
.then((value) {
print(
'************************** table creaated ****************************');
}).catchError((err) {
print(
'************************** error in create table ****************************${err.toString()}');
});
},
onOpen: (db) {
// ignore: avoid_print
print(
'************************** daataBase opened ****************************');
GetDataFromDataBase(db).then((value)
{
tasks=value;
emit(GetFromDataBase());
print(
'************************** your table next ****************************');
print(tasks);
print(
'************************** your table above ****************************');
}
).catchError((err){
print(
'************************** error when get data ${err.toString()} ****************************');
});
},
).then((value) {
Mydatabase=value;
emit(CreatDataBase());
});
}
//============================================================================================
//========================== insert data to dataBase =========================================
InserttTODataBase(
{
required String titel,
required String date,
required String time,
required String status
}) async
{
await Mydatabase.transaction((txn)
{
return txn.rawInsert('INSERT INTO tasks (titel,date,time,status) VALUES ("$titel","$date","$time","$status")')
.then((value)
{
print('************************** inserted successfulyt to id ${value} ****************************');
emit(InsertDataBase());
GetDataFromDataBase(Mydatabase).then((value)
{
tasks=value;
emit(GetFromDataBase());
print( '************************** your table next ****************************');
print(tasks);
print('************************** your table above ****************************');
});
}).catchError((err)
{
print('************************** error when inserted to record ****************************${err.toString()}');
});
});
}
/////////////////////////// get data from dataBase////////////////////////////////////
//============================================================================================
Future<List<Map>> GetDataFromDataBase (database) async
{
return await database.rawQuery('SELECT * FROM tasks');
}
}
您调用的地方没有上下文：
TasksCubit cubitt = TasksCubit.get(context).
也许不是一个好主意，但如果您在构建方法中运行该行，它就会起作用。
对我来说，这是通过使用 this.context 代替 context 来解决的。