Flutter : Class 'Future<List<String>>' 没有实例 getter 'length'

Question

我在 Flutter 应用程序的 SharedPreference 上保存了一个字符串列表，我想在 Provider 中调用它并在小部件中使用它。供应商：

get myTeam => getMyTeam();
  Future<List<String>> getMyTeam() async {
    Future<SharedPreferences> _prefs = SharedPreferences.getInstance();
    final SharedPreferences prefs = await _prefs;
    return prefs.getStringList('team');
  }

我在未来的构建器中使用了它：

Widget build(BuildContext context) {
    return Consumer<GeneralProvider>(
        builder: (context, generalProvider, child) {
      var items = generalProvider.myTeam;
      return FutureBuilder(
          future: items,
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              return ListView.builder(
                  itemCount: items.length,
                  itemBuilder: (context, index) {
                    return ListTile(
                      title: Text('${items[index].club}'),
                    );
                  });
            } else {
              return Text('bad');
            }
          });
    });
  }

我收到错误：Class 'Future<List<String>>' has no instance getter 'length'

我在这里解决了许多问题，例如： Class 'Future<dynamic>' has no instance getter 'length'

但没有解决

Answer 1

将itemCount: items.length改为itemCount: snapshot.length,

以及 FutureBuilder<List<String>(...etc) 的未来建设者。

最终会变成这样：

Widget build(BuildContext context) {
    return Consumer<GeneralProvider>(
        builder: (context, generalProvider, child) {
      var items = generalProvider.myTeam;
      return FutureBuilder<List<String>>(
          future: items,
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              return ListView.builder(
                  itemCount: snapshot.length,
                  itemBuilder: (context, index) {
                    return ListTile(
                     // title: Text('${items[index].club}'),//This will likely throw an error also, because items is a List<String>, there is no method called "club" for Lists. 
                    //Replace it with this to validate:
                    title: Text(snapshot[index]),//This 
   
                    );
                  });
            } else {
              return Text('bad');
            }
          });
    });
  }

Flutter : Class 'Future<List<String>>' 没有实例 getter 'length'

Flutter : Class 'Future<List<String>>' has no instance getter 'length'

flutter

sharedpreferences

provider