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。提供者：

// Increment the x::foo::z
++x::foo::z; 
// Equivalent to ++(x::foo::z)

我在未来的构建器中使用了它：

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

我收到错误：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'); } }); }); }

我在这里找到了许多问题的解决方案，例如： Class 'Future<dynamic>' has no instance getter 'length'

但是没有解决

Answer 1

把itemCount: items.length改成itemCount: snapshot.length，

和未来的建设者FutureBuilder<List<String>(...etc)。

最后会是这样：

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

1 个答案: