本文介绍了Flutter-单选按钮不会显示保存在存储中的默认值(SharedPreferences)的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我尝试获取存储在存储中的单选按钮的默认值( SharedPreferences )。

I try to get default value for the radio button that stored in Storage (SharedPreferences).

但是单选按钮不会将保存的值指向选择列表

下面是我的代码:

app_interface_widget.dart

class AppInterfaceDialogWidget extends StatefulWidget {

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

class _AppInterfaceDialogWidgetState extends State<AppInterfaceDialogWidget> {

  String pickRadioValue;
  @override
    void initState() {
      setState(() {
        this.initRadio();
      });
      super.initState();
  }

  Future initRadio() async {
    pickRadioValue = await app.getPreferredLanguage();
  }

  @override
    void dispose() {
      super.dispose();
    }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        InkWell(
          onTap: (){
            setState(() {
              pickRadioValue = "en";
              app.setNewLanguage("en");
            });
          },
          child: Row(
            children: <Widget>[
              Expanded(
                child: Text("Language 1",style: TextStyle(color: Colors.grey,fontSize: 20.0),),
              ),
              Radio(
                activeColor: Colors.green,
                groupValue: pickRadioValue,
                value: "en",
                onChanged: (val) {
                  setState(() {
                    pickRadioValue = val;
                    app.setNewLanguage("$pickRadioValue");
                  });    
                },
              )
            ],
          ),
        ),
        InkWell(
          onTap: (){
            setState(() {
              pickRadioValue = "id";
              app.setNewLanguage("id");
            });
          },
          child: Row(
            children: <Widget>[  
              Expanded(
                child: Text("Language 2",style: TextStyle(color: Colors.grey,fontSize: 20.0),),
              ),
              Radio(

                activeColor: Colors.green,
                groupValue: pickRadioValue,
                value: "id",
                onChanged: (val) {
                    setState(() {
                      pickRadioValue = val;
                      app.setNewLanguage("$pickRadioValue");
                    });
                  } ,
              )
            ],
          ),
        ),
      ],
    );
  }
}

app.dart

class app {

  Future<Null> init([String language]) async {
    if (_locale == null){
      await setNewLanguage(language);
    }

    return null;
  }

  Future<String> getPreferredLanguage() async {
    return _getApplicationSavedInformation('app');
  }

  Future<String> _getApplicationSavedInformation(String name) async {
    final SharedPreferences prefs = await _prefs;

    return prefs.getString(_storageKey + name) ?? '';
  }

  Future setPreferredLanguage(String lang) async {
    return _setApplicationSavedInformation('app', lang);
  }

  get currentLanguage => getPreferredLanguage();
  get locale => _locale;

...

特别是在这一部分 of app_interface_widget.dart

...
String pickRadioValue;
  @override
    void initState() {
      setState(() {
        this.initRadio();
      });
      super.initState();
  }
  Future initRadio() async {
    pickRadioValue = await app.getPreferredLanguage();
    print ("DEBUG = "+pickRadioValue);
  }
...

我有打印调试值( pickRadioValue ),它会在控制台日志中显示正确的结果,但在单选按钮上根本没有选择。但是如果我设置 pickRadioValue = en ,那么我的单选按钮将显示已保存的值/指向选择列表之一。...

i have print debug value (pickRadioValue) and it show correct result at console log, but it wont make no choice at all at Radio Button. but if i set pickRadioValue = "en" then my Radio button will show the saved value / pointing to the one of choice list....

任何想法吗?

推荐答案

我找到了解决方案,我们可以执行通过使用 then()以其他方式实现异步功能,如下所示:

i found a solution, we can execute async function in other wayby using then() like below :

String pickRadioValue;
  @override
    void initState() {
      setState(() {
        ads.getPreferredLanguage().then((result){
          setState(() {
            print (":: debug result >>>"+result.toString());
            pickRadioValue = result;
          });
        });
      });
      super.initState();
}

通过使用此代码,我的单选按钮显示保存为<$的默认值c $ c> SharedPreferences 。

by using this code, my Radio Button Show default value that saved at SharedPreferences.

这篇关于Flutter-单选按钮不会显示保存在存储中的默认值(SharedPreferences)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

10-27 07:34