The method 'getString' was called on null-CodePudding

I am currently working on an editable profile. But as I run the project I receive the following error:

The method 'getString' was called on null. Receiver: null

Tried calling: getString("aresraa")

How to proceed forward?

class UserPreferences {
  static  SharedPreferences _preferences;
  static const _keyUser = 'aresraa';
  static const myUser = User(
    imagePath:
        'https://images.unsplash.com/photo-1554151228-14d9def656e4?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=333&q=80',
    name: 'Aresrana',
   
    isDarkMode: false,
  );

  static Future init() async =>
      _preferences = await SharedPreferences.getInstance();


  static Future setUser(User user) async {
    final json = jsonEncode(user.toJson());

    await _preferences.setString(_keyUser, json);
  }

  static User getUser() {
    final json = _preferences.getString(_keyUser);

    return json == null ? myUser : User.fromJson(jsonDecode(json));
  }
}

CodePudding user response：

You can check if _preferences is null and get the instance again. Shared Preferences gives you the singleton instance.

static User getUser() {
  _preferences ??= await SharedPreferences.getInstance();
  final json = _preferences.getString(_keyUser);
  return json == null ? myUser : User.fromJson(jsonDecode(json));
}

CodePudding user response：

The best way for you to find out is to do this exercises, 60 min and you will understand whole problem. -> https://dart.dev/codelabs/null-safety