android - 数据共享首选项的问题 - Flutter

Question

当我从 SharedPreferences 获取数据时，它没有在字符串中显示它，并在 accountName: Text(sharedPreferenceEmail) 行中给出错误，错误显示 sharedPreferenceEmail = null

SharedPreferences sharedPreferences;
  String sharedPreferenceEmail;
  String value;

  @override
  void initState() {
    super.initState();
    getDataPreference();
  }

  getDataPreference() async {
    sharedPreferences = await SharedPreferences.getInstance();
    setState(() {
      value = sharedPreferences.getString("email");
      if(value != null) {
        sharedPreferenceEmail = sharedPreferences.getString("email");
      } else {
        sharedPreferenceEmail = "Sign in with Google";
      }
    });
  }

UserAccountsDrawerHeader(
                decoration: BoxDecoration(color: Colors.blueGrey[900]),
                accountName: Text(
                  sharedPreferenceEmail
                  ),

enter image description here

Answer 1

如果您使用异步执行获取值，则需要再次防止 null 以免在 Flutter 构建时在结果尚未到达时引发异常:

accountName: sharedPreferenceEmail != null ? Text( sharedPreferenceEmail ) : Container(),