无法在flutter中检索hashmap

Question

I am new to flutter and trying to save the values in sharepreferences where I have created another class for sharepreferences like below.

Firstly you can see the sharedprefence class , secondly there is onsuccess method where I get values whose value I am passing to save method to save in sharedprefence class and also I am trying to retrieve the saved shareprefernce value in hasmap

 class SharedPreferencesTest {
  ///
  /// Instantiation of the SharedPreferences library
  ///
  final String _kNotificationsPrefs = "allowNotifications";
  final String _loginsession = "loginsession";
  SharedPreferences sharedPreferences;

  /// ------------------------------------------------------------
  /// Method that returns the user decision to allow notifications
  /// ------------------------------------------------------------
  Future<bool> getAllowsNotifications() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    return prefs.getBool(_kNotificationsPrefs) ?? false;
  }

  /// ----------------------------------------------------------
  /// Method that saves the user decision to allow notifications
  /// ----------------------------------------------------------
  Future<bool> setAllowsNotifications(bool value) async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    return prefs.setBool(_kNotificationsPrefs, value);
  }

  /// ------------------------------------------------------------
  /// Method that returns the user decision on sorting order
  /// ------------------------------------------------------------
  Future<String> getSortingOrder() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    return prefs.getString(_loginsession) ?? 'name';
  }

  /// ----------------------------------------------------------
  /// Method that saves the user decision on sorting order
  /// ----------------------------------------------------------
  Future<bool> setSortingOrder(String value) async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    return prefs.setString(_loginsession, value);
  }

  Future saveSession(bool isloggedIn,String passwordval,String accessToken)async{
    print("##session"+"coming");
    sharedPreferences = await SharedPreferences.getInstance();
    sharedPreferences.setBool("is_logged_in", isloggedIn);
    sharedPreferences.setString("password", passwordval);
    sharedPreferences.setString("access_token", accessToken);
    print("##session"+"saved");
  }

  Future<Map<String,String>> getLoginSession() async {
    sharedPreferences = await SharedPreferences.getInstance();
    print("##session"+"retroiving");
    Map<String,String>sessionMap=new HashMap();
    sessionMap['is_logged_in'] = sharedPreferences.getBool("is_logged_in").toString();
    sessionMap['access_token'] = sharedPreferences.getString("access_token");
    sessionMap['password'] = sharedPreferences.getString("password");
    return sessionMap;
  }

And i am trying to retrieve the saved value like the below

@override
  void onLoginSuccess(LoginModel user) {
    createSnackBar("successfully logged In", _scaffoldKey);
    saveName(true, user.secret_key,user.access_token);
    getCredential();
  }

 Future saveName(bool isloggedIn,String passwordval,String accessToken)async{
    sharedPreferences=SharedPreferencesTest();
    sharedPreferences.saveSession(true, passwordval,accessToken);
  }

  getCredential() async {
    print("###coming inside getcredentials");
    Map<String,String>sessionMap=new HashMap();
    sharedPreferences=SharedPreferencesTest();
    setState(() {

      sessionMap= sharedPreferences.getLoginSession() as Map<String, String>;
      if (sessionMap["is_logged_in"] != null) {
        if (isloggedIn) {
          print("###isloggedin=true");
          passwordController.text = sessionMap["password"].toString();
          Navigator.of(context).pushReplacementNamed('/drawer-page');
          sessionMap['access_token'] = sessionMap["access_token"].toString();
          sessionMap['password'] = sessionMap["password"].toString();
        } else {
          print("###isloggedin=false");
          passwordController.clear();
        }
      } else {
        isloggedIn = false;
      }
    });
    return sessionMap;
  }

Any help would be much appreciated. I get an error like the below 
E/flutter (29347): type 'Future<Map<String, String>>' is not a subtype of type 'Map<String, String>' in typecast

Please let me know what is the problem whether the preferences are not cast while retrieving or what is the problem.

Answer 1

这可能是因为您尝试从.getBool和.getString获取的值也需要await 。