未处理的异常：未找到 MaterialLocalizations
Unhandled Exception: No MaterialLocalizations found
我正在尝试使用 firebase 远程配置在我的应用程序版本更改时显示强制更新我的应用程序的警报对话框，从 initState() 调用 versionCheck(context) 一切都很好但是当我调用 showVersionDialog() 方法时出现错误，这是我的代码
void main() => runApp(UniApp());
class UniApp extends StatefulWidget {
@override
State<StatefulWidget> createState() => _UniappMainState();
}
class _UniappMainState extends State<UniApp> {
AppTranslationsDelegate _newLocaleDelegate;
@override
void initState() {
super.initState();
setlocaleFromSharedPreference();
_newLocaleDelegate = AppTranslationsDelegate(newLocale: null);
UAAppContext.getInstance().onLocaleChanged = onLocaleChange;
//calling versionCheck
versionCheck(context);
}
versionCheck(context) async {
//Get Current installed version of app
final PackageInfo info = await PackageInfo.fromPlatform();
double currentVersion = double.parse(info.version.trim().replaceAll(".", ""));
//Get Latest version info from firebase config
final RemoteConfig remoteConfig = await RemoteConfig.instance;
try {
// Using default duration to force fetching from remote server.
await remoteConfig.fetch(expiration: const Duration(seconds: 0));
remoteConfig.setConfigSettings(RemoteConfigSettings(debugMode: true));
await remoteConfig.activateFetched();
remoteConfig.getString('force_update_current_version');
double newVersion = double.parse(remoteConfig
.getString('force_update_current_version')
.trim()
.replaceAll(".", ""));
print("cv-"+currentVersion.toString()+"nv--"+newVersion.toString());
if (newVersion > currentVersion) {
_showVersionDialog(context);
}
} on FetchThrottledException catch (exception) {
// Fetch throttled.
print(exception);
} catch (exception) {
print('Unable to fetch remote config. Cached or default values will be '
'used');
}
}
//Show Dialog to force user to update
_showVersionDialog(context) async {
await showDialog<String>(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
String title = "New Update Available";
String message =
"There is a newer version of app available please update it now.";
String btnLabel = "Update Now";
String btnLabelCancel = "Later";
return new AlertDialog(
title: Text(title),
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text(btnLabel),
onPressed: () => _launchURL(CommonConstants.PLAY_STORE_URL),
),
FlatButton(
child: Text(btnLabelCancel),
onPressed: () => Navigator.pop(context),
),
],
);
},
);
}
_launchURL(String url) async {
if (await canLaunch(url)) {
await launch(url);
} else {
throw 'Could not launch $url';
}
}
void onLocaleChange(Locale locale) {
setState(() {
UAAppContext.getInstance().changeLanguage(locale.languageCode);
_newLocaleDelegate = AppTranslationsDelegate(newLocale: locale);
});
}
setlocaleFromSharedPreference() {
UAAppContext.getInstance().getLocale().then((locale) {
if (locale == 'en') return;
setState(() {
_newLocaleDelegate = AppTranslationsDelegate(newLocale: Locale(locale));
});
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
initialRoute: '/',
routes: {
'/': (context) => SplashScreen(),
CommonConstants.homeRoute: (context) { RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return HomeScreen(
parentAppId: r.appId
);
} else return HomeScreen();},
CommonConstants.loginRoute: (context) => LoginScreen(),
CommonConstants.projectGroupRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectGroupScreen(
appId: r.appId,
attributes: r.groupingAttributes,
sortType: r.sortType,
);
} else
return SplashScreen();
},
CommonConstants.projectListRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectListScreen(
appId: r.appId,
sortType: r.sortType,
groupingKey: r.groupingKey,
groupingValue: r.groupingValue,
projectMasterDataTableList: r.projectMasterDataTableList,
);
} else
return SplashScreen();
},
CommonConstants.projectFormRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectFormScreen(
appId: r.appId,
projectId: r.projectId,
formActiontype: r.formActionType,
projectMasterDataKeyToValueMap: r.projectFieldsKeyToValue,
);
} else
return SplashScreen();
},
CommonConstants.getOTPRoute: (context) => GetOTPScreen(),
CommonConstants.changePasswordRoute: (context) =>
ChangePasswordScreen(),
CommonConstants.userRegistrationRoute: (context) =>
UserRegisterScreen(),
CommonConstants.downloadsRoute: (context) => DownloadScreen(),
CommonConstants.filterRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return FilterScreen(
appId: r.appId,
projectList: UAAppContext.getInstance().projectList,
filterKeyToValue:
UAAppContext.getInstance().filterSelectedValueMap,
);
} else
return SplashScreen();
},
CommonConstants.geoTaggingRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null &&
r.geoTaggingWidgetId != null &&
r.geoTaggingWidgetId.isNotEmpty) {
return GeotaggingWidget(
ctxt: r.context,
id: r.geoTaggingWidgetId,
gpsValidation: r.gpsValidation,
projLat: r.projLat,
projLon: r.projLon,
);
} else
return SplashScreen();
},
CommonConstants.profileRoute: (context) => UserProfileScreen(),
},
debugShowCheckedModeBanner: false,
// theme: UniappColorTheme.defaultTheme,
theme: UniappColorTheme.getTheme(),
localizationsDelegates: [
_newLocaleDelegate,
//provides localised strings
GlobalMaterialLocalizations.delegate,
//provides RTL support
GlobalWidgetsLocalizations.delegate,
],
supportedLocales: [
const Locale("en", ""),
const Locale("hi", ""),
const Locale("or", "")
],
);
}
}
这些是我在显示 showVersionDialog() 方法时收到的错误消息，没有理解它的实际含义。
E/flutter (12951): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: No MaterialLocalizations found.
E/flutter (12951): UniApp widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.
E/flutter (12951): Localizations are used to generate many different messages, labels, and abbreviations which are used by the material library.
E/flutter (12951): To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to include them automatically, or add a Localization widget with a MaterialLocalizations delegate.
E/flutter (12951): The specific widget that could not find a MaterialLocalizations ancestor was:
E/flutter (12951): UniApp
E/flutter (12951): The ancestors of this widget were:
E/flutter (12951): [root]
E/flutter (12951): #0 debugCheckHasMaterialLocalizations.<anonymous closure> (package:flutter/src/material/debug.dart:72:7)
E/flutter (12951): #1 debugCheckHasMaterialLocalizations (package:flutter/src/material/debug.dart:92:4)
E/flutter (12951): #2 showDialog (package:flutter/src/material/dialog.dart:843:10)
E/flutter (12951): #3 _UniappMainState._showVersionDialog (package:Uniapp/main.dart:80:11)
E/flutter (12951): #4 _UniappMainState.versionCheck (package:Uniapp/main.dart:67:9)
E/flutter (12951): <asynchronous suspension>
E/flutter (12951): #5 _UniappMainState.initState (package:Uniapp/main.dart:44:5)
我只是通过创建一个带有变量
的单例 class (MySingletonClass) 来解决这个问题
BuildContext get context => _context;
得到这个变量
MySingletonClass.getInstance().context;
将单例 class 上下文传递给 showdialog contex
final context = MySingletonClass.getInstance().context;
//calling showVersionDialong
_showVersionDialog(context);
我在使用 rflutter_alert package 显示 pop-up 警报对话框时遇到了类似的问题。
我的代码结构是：
void main () {
runApp(QuizPage)
}
在 QuizPage 内部，构建方法 returns:
return MaterialApp(
home: Scaffold())
我按照本文说明中的第二种方法解决了这个问题：https://www.fluttercampus.com/guide/70/how-to-solve-no-materiallocalizations-found-error-exception-in-flutter/
现在我的代码结构是：
runApp(MaterialApp(home: MyApp()))
MyAppreturnsQuizPage
我正在尝试使用 firebase 远程配置在我的应用程序版本更改时显示强制更新我的应用程序的警报对话框，从 initState() 调用 versionCheck(context) 一切都很好但是当我调用 showVersionDialog() 方法时出现错误，这是我的代码
void main() => runApp(UniApp());
class UniApp extends StatefulWidget {
@override
State<StatefulWidget> createState() => _UniappMainState();
}
class _UniappMainState extends State<UniApp> {
AppTranslationsDelegate _newLocaleDelegate;
@override
void initState() {
super.initState();
setlocaleFromSharedPreference();
_newLocaleDelegate = AppTranslationsDelegate(newLocale: null);
UAAppContext.getInstance().onLocaleChanged = onLocaleChange;
//calling versionCheck
versionCheck(context);
}
versionCheck(context) async {
//Get Current installed version of app
final PackageInfo info = await PackageInfo.fromPlatform();
double currentVersion = double.parse(info.version.trim().replaceAll(".", ""));
//Get Latest version info from firebase config
final RemoteConfig remoteConfig = await RemoteConfig.instance;
try {
// Using default duration to force fetching from remote server.
await remoteConfig.fetch(expiration: const Duration(seconds: 0));
remoteConfig.setConfigSettings(RemoteConfigSettings(debugMode: true));
await remoteConfig.activateFetched();
remoteConfig.getString('force_update_current_version');
double newVersion = double.parse(remoteConfig
.getString('force_update_current_version')
.trim()
.replaceAll(".", ""));
print("cv-"+currentVersion.toString()+"nv--"+newVersion.toString());
if (newVersion > currentVersion) {
_showVersionDialog(context);
}
} on FetchThrottledException catch (exception) {
// Fetch throttled.
print(exception);
} catch (exception) {
print('Unable to fetch remote config. Cached or default values will be '
'used');
}
}
//Show Dialog to force user to update
_showVersionDialog(context) async {
await showDialog<String>(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
String title = "New Update Available";
String message =
"There is a newer version of app available please update it now.";
String btnLabel = "Update Now";
String btnLabelCancel = "Later";
return new AlertDialog(
title: Text(title),
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text(btnLabel),
onPressed: () => _launchURL(CommonConstants.PLAY_STORE_URL),
),
FlatButton(
child: Text(btnLabelCancel),
onPressed: () => Navigator.pop(context),
),
],
);
},
);
}
_launchURL(String url) async {
if (await canLaunch(url)) {
await launch(url);
} else {
throw 'Could not launch $url';
}
}
void onLocaleChange(Locale locale) {
setState(() {
UAAppContext.getInstance().changeLanguage(locale.languageCode);
_newLocaleDelegate = AppTranslationsDelegate(newLocale: locale);
});
}
setlocaleFromSharedPreference() {
UAAppContext.getInstance().getLocale().then((locale) {
if (locale == 'en') return;
setState(() {
_newLocaleDelegate = AppTranslationsDelegate(newLocale: Locale(locale));
});
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
initialRoute: '/',
routes: {
'/': (context) => SplashScreen(),
CommonConstants.homeRoute: (context) { RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return HomeScreen(
parentAppId: r.appId
);
} else return HomeScreen();},
CommonConstants.loginRoute: (context) => LoginScreen(),
CommonConstants.projectGroupRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectGroupScreen(
appId: r.appId,
attributes: r.groupingAttributes,
sortType: r.sortType,
);
} else
return SplashScreen();
},
CommonConstants.projectListRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectListScreen(
appId: r.appId,
sortType: r.sortType,
groupingKey: r.groupingKey,
groupingValue: r.groupingValue,
projectMasterDataTableList: r.projectMasterDataTableList,
);
} else
return SplashScreen();
},
CommonConstants.projectFormRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return ProjectFormScreen(
appId: r.appId,
projectId: r.projectId,
formActiontype: r.formActionType,
projectMasterDataKeyToValueMap: r.projectFieldsKeyToValue,
);
} else
return SplashScreen();
},
CommonConstants.getOTPRoute: (context) => GetOTPScreen(),
CommonConstants.changePasswordRoute: (context) =>
ChangePasswordScreen(),
CommonConstants.userRegistrationRoute: (context) =>
UserRegisterScreen(),
CommonConstants.downloadsRoute: (context) => DownloadScreen(),
CommonConstants.filterRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null && r.appId != null && r.appId.isNotEmpty) {
return FilterScreen(
appId: r.appId,
projectList: UAAppContext.getInstance().projectList,
filterKeyToValue:
UAAppContext.getInstance().filterSelectedValueMap,
);
} else
return SplashScreen();
},
CommonConstants.geoTaggingRoute: (context) {
RouteParameters r = ModalRoute.of(context).settings.arguments;
if (r != null &&
r.geoTaggingWidgetId != null &&
r.geoTaggingWidgetId.isNotEmpty) {
return GeotaggingWidget(
ctxt: r.context,
id: r.geoTaggingWidgetId,
gpsValidation: r.gpsValidation,
projLat: r.projLat,
projLon: r.projLon,
);
} else
return SplashScreen();
},
CommonConstants.profileRoute: (context) => UserProfileScreen(),
},
debugShowCheckedModeBanner: false,
// theme: UniappColorTheme.defaultTheme,
theme: UniappColorTheme.getTheme(),
localizationsDelegates: [
_newLocaleDelegate,
//provides localised strings
GlobalMaterialLocalizations.delegate,
//provides RTL support
GlobalWidgetsLocalizations.delegate,
],
supportedLocales: [
const Locale("en", ""),
const Locale("hi", ""),
const Locale("or", "")
],
);
}
}
这些是我在显示 showVersionDialog() 方法时收到的错误消息，没有理解它的实际含义。
E/flutter (12951): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: No MaterialLocalizations found.
E/flutter (12951): UniApp widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.
E/flutter (12951): Localizations are used to generate many different messages, labels, and abbreviations which are used by the material library.
E/flutter (12951): To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to include them automatically, or add a Localization widget with a MaterialLocalizations delegate.
E/flutter (12951): The specific widget that could not find a MaterialLocalizations ancestor was:
E/flutter (12951): UniApp
E/flutter (12951): The ancestors of this widget were:
E/flutter (12951): [root]
E/flutter (12951): #0 debugCheckHasMaterialLocalizations.<anonymous closure> (package:flutter/src/material/debug.dart:72:7)
E/flutter (12951): #1 debugCheckHasMaterialLocalizations (package:flutter/src/material/debug.dart:92:4)
E/flutter (12951): #2 showDialog (package:flutter/src/material/dialog.dart:843:10)
E/flutter (12951): #3 _UniappMainState._showVersionDialog (package:Uniapp/main.dart:80:11)
E/flutter (12951): #4 _UniappMainState.versionCheck (package:Uniapp/main.dart:67:9)
E/flutter (12951): <asynchronous suspension>
E/flutter (12951): #5 _UniappMainState.initState (package:Uniapp/main.dart:44:5)
我只是通过创建一个带有变量
的单例 class (MySingletonClass) 来解决这个问题 BuildContext get context => _context;
得到这个变量
MySingletonClass.getInstance().context;
将单例 class 上下文传递给 showdialog contex
final context = MySingletonClass.getInstance().context;
//calling showVersionDialong
_showVersionDialog(context);
我在使用 rflutter_alert package 显示 pop-up 警报对话框时遇到了类似的问题。 我的代码结构是：
void main () {
runApp(QuizPage)
}
在 QuizPage 内部，构建方法 returns:
return MaterialApp(
home: Scaffold())
我按照本文说明中的第二种方法解决了这个问题：https://www.fluttercampus.com/guide/70/how-to-solve-no-materiallocalizations-found-error-exception-in-flutter/
现在我的代码结构是：
runApp(MaterialApp(home: MyApp()))
MyAppreturnsQuizPage