flutter - 加载主页小部件（MyHomepage）时出错
问题描述
在运行我的应用程序默认页面 (Homepage) 时出现以下错误。
════════ Exception caught by widgets library ═══════════
The following ArgumentError was thrown building MyHomePage(dirty, dependencies: [MediaQuery, _EffectiveTickerMode], state: _MyHomePageState#7da5f(ticker inactive)):
Invalid argument(s)
**The Tracker showing the following reasons:**
The relevant error-causing widget was:
MyHomePage file:///F:/Orangebd/app/GoogleDriveClone-Flutter/lib/Screen/Home.dart:37:15
When the exception was thrown, this was the stack:
#0 _StringBase.+ (dart:core-patch/string_patch.dart:272:57)
#1 _MyHomePageState.build (package:googledriveclone_flutter/Screen/Home.dart:133:45)
#2 StatefulElement.build (package:flutter/src/widgets/framework.dart:4716:27)
#3 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4599:15)
#4 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4772:11)
...
══════════════════════════════════════════
在该错误期间，屏幕出现类似的东西
这是我的主页代码
import 'package:fab_circular_menu/fab_circular_menu.dart';
//import 'package:file_picker/file_picker.dart';
import 'package:floating_action_bubble/floating_action_bubble.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:get/get.dart';
import 'package:googledriveclone_flutter/Screen/Files.dart';
import 'package:googledriveclone_flutter/Screen/HomeScreen.dart';
import 'package:googledriveclone_flutter/Screen/LoginPage.dart';
import 'package:googledriveclone_flutter/Screen/Profile.dart';
import 'package:googledriveclone_flutter/Widget/constants.dart';
import 'package:prompt_dialog/prompt_dialog.dart';
import 'package:sk_alert_dialog/sk_alert_dialog.dart';
import 'package:storage_capacity/storage_capacity.dart';
import 'IssudFile.dart';
void main() {
runApp(HomePage());
}
class HomePage extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
try {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Digilocker',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Digilocker'),
);
}
catch(e){
print('Loading expception of page'+e.toString());
}
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
Widget _widgetBody = HomeScreen();
int _currrentIndex = 0;
Animation<double> _animation;
AnimationController _animationController;
TextEditingController _foldername = TextEditingController();
String _fileName;
var scaffoldKey = GlobalKey<ScaffoldState>();
bool isFolder;
double _diskSpace = 0;
var _freespace ;
var _freespacemb;
var _occupiedSpace ;
var _totalSpace;
@override
void initState() {
// TODO: implement initState
// _controller.addListener(() => _extension = _controller.text);
_getStorgeInfo();
_animationController = AnimationController(
vsync: this,
duration: Duration(milliseconds: 300),
);
final curvedAnimation = CurvedAnimation(curve: Curves.easeInOut, parent: _animationController);
_animation = Tween<double>(begin: 0, end: 1).animate(curvedAnimation);
// initDiskSpace();
super.initState();
}
@override
void dispose() {
_animationController.dispose();
super.dispose();
}
void _onItemTapped(int index) async{
setState(() {
if(index == 0){
_currrentIndex = index;
_widgetBody = HomeScreen();
}
else if(index == 1){
_currrentIndex = index;
_widgetBody = MyIssuedDocScreen();
}
else if(index == 2){
_currrentIndex = index;
_widgetBody = Center(child: Text('Shared documents'),);
}
else if(index == 3){
_currrentIndex = index;
_widgetBody = MyDriveScreen();
}
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
endDrawerEnableOpenDragGesture: false, // This way it will not open
// endDrawer: Drawer(),
drawer: new Drawer(
elevation: 10,
child: new ListView(
padding: EdgeInsets.all(0),
children: <Widget>[
DrawerHeader(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Image.asset('assets/digi_locker.png', width: MediaQuery.of(context).size.width*0.30,),
SizedBox(height: 10,),
Text('Available space: '+_freespace+'\t (MB)'),
]
),
decoration: BoxDecoration(
color: kPrimaryLightColor,
),
),
ListTile(
leading: Icon(Icons.person),
title: Text('My profile'),
onTap: () {
// Get.back();
Get.to(profilePage());
},
),
Divider(),
ListTile(
leading: Icon(Icons.create_new_folder),
title: Text('Create folder'),
onTap: () {
// Get.back();
_showMyDialog();
},
),
ListTile(
leading: Icon(Icons.cloud_upload_rounded),
title: Text('File upload'),
onTap: () {
// Get.back();
},
),
ListTile(
leading: Icon(Icons.six_ft_apart_outlined),
title: Text('Issued documents'),
onTap: () {
// Get.back();
},
),
Divider(),
ListTile(
leading: Icon(Icons.translate_rounded),
title: Text('Change lagnuage'),
onTap: () {
// Get.back();
//Get.offAll(LoginPage());
//Do some stuff here
//Closing programmatically - very less practical use
scaffoldKey.currentState.openEndDrawer();
},
),
ListTile(
leading: Icon(Icons.logout),
title: Text('Logout'),
onTap: () {
// Get.back();
Get.offAll(LoginPage());
//Do some stuff here
//Closing programmatically - very less practical use
scaffoldKey.currentState.openEndDrawer();
},
)
],
),
),
appBar: AppBar(
elevation: 0,
backgroundColor: Colors.white,
brightness: Theme.of(context).brightness,
title: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.center,
children:
[
Expanded(
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(35)),
color: Colors.grey.shade50,
),
child: TextFormField(
decoration: InputDecoration(
hintText: "Search in locker",
border: InputBorder.none,
icon: Container(
margin: EdgeInsets.only(left: 10),
child: Icon(Icons.search, color: kPrimaryColor,)
),
),
),
),
),
]
),
iconTheme: IconThemeData(color: kPrimaryColor),
actions: <Widget>[
IconButton(
onPressed: (){
print("Sync started");
showSnackMessage(context,"Sync Started please wait...", scaffoldKey,'');
},
icon: Icon(
Icons.sync,
color:kPrimaryColor,
),
),
IconButton(
icon: Container(
height: 50,
width: 50,
margin: EdgeInsets.all(5),
child: CircleAvatar(
radius: 14.0,
backgroundColor: Colors.white,
child: CircleAvatar(
radius: 14.0,
backgroundColor: Colors.grey[200],
backgroundImage: NetworkImage("https://qph.fs.quoracdn.net/main-qimg-11ef692748351829b4629683eff21100.webp"),
),
),
),
onPressed: () {
// do something
},
)
],
),
body: SafeArea(
child: Container(
padding: EdgeInsets.all(15.0),
child: _widgetBody
),
),
floatingActionButtonLocation: FloatingActionButtonLocation.endFloat,
//Init Floating Action Bubble
floatingActionButton: FloatingActionBubble(
// Menu items
items: <Bubble>[
// Floating action menu item
Bubble(
title:"Upload",
iconColor :kPrimaryColor,
bubbleColor : Colors.white.withOpacity(0.9),
titleStyle:TextStyle(fontSize: 16 , color: kPrimaryColor),
icon:Icons.cloud_upload,
onPress: () {
// OpenFilePicker();
_animationController.reverse();
_openFileType(context);
},
),
// Floating action menu item
Bubble(
title:"Folder",
icon:Icons.create_new_folder,
iconColor :kPrimaryColor,
bubbleColor : Colors.white.withOpacity(0.9),
titleStyle:TextStyle(fontSize: 16 , color: kPrimaryColor),
onPress: () {
_animationController.reverse();
print('creating folder');
_showMyDialog();
},
),
//Floating action menu item
],
// animation controller
animation: _animation,
// On pressed change animation state
onPress: _animationController.isCompleted
? _animationController.reverse
: _animationController.forward,
// Floating Action button Icon color
iconColor: kPrimaryColor,
// Flaoting Action button Icon
icon: AnimatedIcons.menu_close,
),
bottomNavigationBar: BottomNavigationBar(
currentIndex: _currrentIndex,
type: BottomNavigationBarType.fixed,
showSelectedLabels: true,
showUnselectedLabels: true,
selectedItemColor: kPrimaryColor,
onTap: _onItemTapped,
items: [
BottomNavigationBarItem(
icon: _currrentIndex==0?Icon(Icons.home,size: 25,):Icon(Icons.home_outlined,size: 25),
title: Text("Home")
),
BottomNavigationBarItem(
icon: _currrentIndex==1?Icon(Icons.file_download_done,size: 25,):Icon(Icons.file_download_done_outlined,size: 25),
title: Text("Issued")
),
BottomNavigationBarItem(
icon: _currrentIndex==2?Icon(Icons.supervised_user_circle,size: 25,):Icon(Icons.supervised_user_circle,size: 25),
title: Text("Shared")
),
BottomNavigationBarItem(
icon: _currrentIndex==3?Icon(Icons.folder,size: 25,):Icon(Icons.folder_open,size: 25),
title: Text("My locker")
),
],
), );
}
Future<void> _showMyDialog() async {
return showDialog<void>(
context: context,
barrierDismissible: false, // user must tap button!
builder: (BuildContext context) {
return AlertDialog(
backgroundColor: Colors.white,
elevation: 13,
title: Text('Create folder'),
content: TextField(
onChanged: (value) { },
controller: _foldername,
decoration: InputDecoration(hintText: "your folder/directory name",
suffixIcon: IconButton(
onPressed: () => _foldername.clear(),
icon: Icon(Icons.clear),
),
),
),
actions: <Widget>[
TextButton(
child: Text('Cancel', style: TextStyle(color: Colors.red),),
onPressed: () {
//Navigator.pop(_);
Navigator.of(context).pop();
// _animationController.reverse();
},
),
TextButton(
child: Text('Create', style: TextStyle(color: kPrimaryColor),),
onPressed: () {
createFolder(context, scaffoldKey, _foldername.text.toString()) ;
Get.back();
//Navigator.of(context).pop();
// _animationController.reverse();
},
),
],
);
},
);
}
void _openFileType(BuildContext context) {
SKAlertDialog.show(
context: context,
type: SKAlertType.radiobutton,
radioButtonAry: {'Certificate': 1, 'Signature': 2, 'NID': 3, 'Passport': 4, 'Driving licence': 5},
title: 'Choose File category',
onCancelBtnTap: (value) {
print('Cancel Button Tapped');
Navigator.of(context).pop(false);
},
onRadioButtonSelection: (value) {
print('onRadioButtonSelection $value');
},
);
}
/* Future<void> initDiskSpace() async {
double diskSpace = 0;
diskSpace = await DiskSpace.getFreeDiskSpace;
if (!mounted) return;
setState(() {
_diskSpace = diskSpace;
});
}
*/
Future<void> _getStorgeInfo() async{
_freespace = await StorageCapacity.getFreeSpace;
//_freespacemb = await StorageCapacity.toMegaBytes(double.parse(_freespace.toString()));
_occupiedSpace = await StorageCapacity.getOccupiedSpace;
_totalSpace = await StorageCapacity.getTotalSpace;
}
}
注意：如果我热重新加载此页面，它会再次正常工作
请帮忙。
解决方案
问题是，您在initState方法中获取数据，但是在将数据初始化为 之前，您的小部件的构建已经完成_freespace，这就是出现错误的原因。
作为一种解决方案，我建议从 中删除_getStorgeInfo()调用initState，并实现以下结构：
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
endDrawerEnableOpenDragGesture: false, // This way it will not open
// endDrawer: Drawer(),
drawer: new Drawer(
...
),
appBar: AppBar(
...
),
body: SafeArea(
child: Container(
padding: EdgeInsets.all(15.0),
child: FutureBuilder(
future: _getStorgeInfo(),
builder: (context, snapshot) {
if(snapshot.connectionState!=ConnectionState.Done) return CircularProgressIndicator();
return _widgetBody;
},
),
),
));
}
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