未处理的异常:无效参数(值)：不能为空颤振2
未处理的异常:无效参数(值)：不能为空颤振2
提问于 2021-05-27 10:49:17
在切换到Flutter 2之前，我使用的是SharedPreferences的旧版本，没有问题，现在我有了最新版本，我能够将int类型的值存储在应用程序所有方面使用的单独类中，但是在移动和更新所有试图保存值的尝试之后，我会遇到以下问题：
[ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: Invalid argument(s) (value): Must not be null
E/flutter (24208): #0 ArgumentError.checkNotNull (dart:core/errors.dart:185:27)
E/flutter (24208): #1 SharedPreferences._setValue (package:shared_preferences/shared_preferences.dart:147:19)
E/flutter (24208): #2 SharedPreferences.setString (package:shared_preferences/shared_preferences.dart:133:7)
E/flutter (24208): #3 MyPreferences.commit (package:Hasa/MyPreferences.dart:114:30)
E/flutter (24208): #4 _SettingsPageState._handleRadioValueChange.<anonymous closure> (package:Hasa/Settings.dart:149:26)
E/flutter (24208): #5 State.setState (package:flutter/src/widgets/framework.dart:1267:30)
E/flutter (24208): #6 _SettingsPageState._handleRadioValueChange (package:Hasa/Settings.dart:132:5)
E/flutter (24208): #7 _RadioState._handleChanged (package:flutter/src/material/radio.dart:404:24)
E/flutter (24208): #8 RenderToggleable._handleTap (package:flutter/src/material/toggleable.dart:440:19)
E/flutter (24208): #9 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter (24208): #10 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:607:11)
E/flutter (24208): #11 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:296:5)
E/flutter (24208): #12 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:267:7)
E/flutter (24208): #13 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:157:27)
E/flutter (24208): #14 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:385:20)
E/flutter (24208): #15 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:361:22)
E/flutter (24208): #16 RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:278:11)
E/flutter (24208): #17 GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:316:7)
E/flutter (24208): #18 GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:280:5)
E/flutter (24208): #19 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:238:7)
E/flutter (24208): #20 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:221:7)
E/flutter (24208): #21 _rootRunUnary (dart:async/zone.dart:1370:13)
E/flutter (24208): #22 _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter (24208): #23 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1170:7)
E/flutter (24208): #24 _invoke1 (dart:ui/hooks.dart:180:10)
E/flutter (24208): #25 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:276:7)
E/flutter (24208): #26 _dispatchPointerDataPacket (dart:ui/hooks.dart:96:31)
E/flutter (24208): 我试图设置值以保存用户为应用程序选择的显示语言。
通过以下代码：
void _handleRadioValueChange(int value) {
_radioValue = value;
setState(() {
switch (_radioValue) {
case 1:
SaveLang=1;
context.locale = Locale('en', 'US');
_myPreferences.lang = SaveLang;
_myPreferences.commit();
break;
case 2:
SaveLang=2;
context.locale = Locale('ar', 'SA');
_myPreferences.lang = SaveLang;
_myPreferences.commit();
break;
}
});
}SharedPreferences类：
class MyPreferences {
static const LANG = "lang";
static final MyPreferences instance = MyPreferences._internal();
static SharedPreferences _sharedPreferences;
int lang;
MyPreferences._internal() {}
factory MyPreferences() => instance;
Future<SharedPreferences> get preferences async {
if (_sharedPreferences != null) {
return _sharedPreferences;
} else {
_sharedPreferences = await SharedPreferences.getInstance();
lang = _sharedPreferences.getInt(LANG);
return _sharedPreferences;
}
}
Future<bool> commit() async {
_sharedPreferences ??= await SharedPreferences.getInstance();
await _sharedPreferences.setInt(LANG, lang);
}
Future<MyPreferences> init() async {
_sharedPreferences = await preferences;
return this;
}
}我不知道如何解决这个问题，也不知道它出现的原因。另一方面，我可以保存字符串值，而不会出现这个问题。
回答 2
Stack Overflow用户
回答已采纳
发布于 2021-05-27 12:03:20
您设置了null值，因此在新版本的颤振中不能。请确保您的lang值不为空。
Future<bool> commit() async {
_sharedPreferences ??= await SharedPreferences.getInstance();
if(lang != null){
await _sharedPreferences.setInt(LANG, lang);
return true;
}
else { // you can set default or return false;
await _sharedPreferences.setInt(LANG, 1);
return false;
}
return false;
}Stack Overflow用户
发布于 2021-10-27 19:10:25
等待_sharedPreferences.setInt(朗，郎)；
lang在ur代码中为空，在新版本> 2.0.0中不能允许。
如果您希望将yaml中的版本更改为旧版本，或者只需给lang修复错误
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/67720594
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