Flutter SharedPreference do not persist

Question

I want to save user preferences using Flutter\'s SharedPreference. But the registered preferences are ALL null at new start (when app have been closed, not unis

Answer 1

import 'package:shared_preferences/shared_preferences.dart';
 
class MySharedPreferences {
  MySharedPreferences._privateConstructor();
 
  static final MySharedPreferences instance =
      MySharedPreferences._privateConstructor();
 
  setStringValue(String key, String value) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    myPrefs.setString(key, value);
  }
 
  Future getStringValue(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.getString(key) ?? "";
  }
 
  Future containsKey(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.containsKey(key);
  }
 
  removeValue(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.remove(key);
  }
 
  removeAll() async{
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.clear();
  }
 
}

For more reference: Flutter Shared Preferences Tutorial