Flutter-SharedPreference.dart

import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';

class PreferenceManager {
  
  static PreferenceManager sharedInstance = PreferenceManager();

  //<<<<<<<<<<<<<<<<<<<<<<<< All Setters <<<<<<<<<<<<<<<<<<<<<<
  Future<bool> putString(String key, String value) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.setString(key, value);
  }

  Future<bool> putStringList(String key, List<String> value) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.setStringList(key, value);
  }

  Future<bool> putInt(String key, int value) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.setInt(key, value);
  }

  Future<bool> putBoolean(String key, bool value) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.setBool(key, value);
  }

  Future<bool> putDouble(String key, double value) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.setDouble(key, value);
  }

  Future<bool> putMap(String key, Map<String, dynamic> dataMap) async {
    return await putString(key, json.encode(dataMap));  // json.encode() converts map to string....
  }

  // >>>>>>>>>>>>>>>>>>>>>>>>>> All Getters >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

  Future<String> getString(String key, {String defaultValue = ""}) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    String value = _prefs.getString(key);
    return value != null ? value : defaultValue;
  }

  Future<List<String>> getStringList(String key) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    List<String> value = _prefs.getStringList(key);
    return value != null ? value : List<String>();
  }

  Future<double> getDouble(String key, {double defaultValue = 0}) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    double value = _prefs.getDouble(key);
    return value != null ? value : defaultValue;
  }

  Future<int> getInt(String key, {int defaultValue = 0}) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    int value = _prefs.getInt(key);
    return value != null ? value : defaultValue;
  }

  Future<bool> getBoolean(String key, {bool defaultValue = false}) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    bool value = _prefs.getBool(key);
    return value != null ? value : defaultValue;
  }

  Future<Map<String, dynamic>> getMap(String key) async {
    return json.decode(await getString(key));   // json.decode() converts string to Map.......
  }

  // >>>>>>>>>>>> CLEAR AND REMOVE DATA >>>>>>>>>>>>>>>>>>>
  Future<bool> remove(String key) async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    return _prefs.remove(key);
  }

  Future<void> clear() async {
    SharedPreferences _prefs = await SharedPreferences.getInstance();
    _prefs.clear();
  }
}

prefs.dart

import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

class Prefs {
  static SharedPreferences _prefs;
  static Map<String, dynamic> _memoryPrefs = Map<String, dynamic>();

  static Future<SharedPreferences> load() async {
    if (_prefs == null) {
      _prefs = await SharedPreferences.getInstance();
    }
    return _prefs;
  }

  //<<<<<<<<<<<<<<<<<<<<<<<< All Setters <<<<<<<<<<<<<<<<<<<<<<
  static void setString(String key, String value) {
    _prefs.setString(key, value);
    _memoryPrefs[key] = value;
  }

  static void setInt(String key, int value) {
    _prefs.setInt(key, value);
    _memoryPrefs[key] = value;
  }

  static void setDouble(String key, double value) {
    _prefs.setDouble(key, value);
    _memoryPrefs[key] = value;
  }

  static void setBool(String key, bool value) {
    _prefs.setBool(key, value);
    _memoryPrefs[key] = value;
  }

    // >>>>>>>>>>>>>>>>>>>>>>>>>> All Getters >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

  static String getString(String key, {String def}) {
    String val;
    if (_memoryPrefs.containsKey(key)) {
      val = _memoryPrefs[key];
    }
    if (val == null) {
      val = _prefs.getString(key);
    }
    if (val == null) {
      val = def;
    }
    _memoryPrefs[key] = val;
    return val;
  }

  static int getInt(String key, {int def}) {
    int val;
    if (_memoryPrefs.containsKey(key)) {
      val = _memoryPrefs[key];
    }
    if (val == null) {
      val = _prefs.getInt(key);
    }
    if (val == null) {
      val = def;
    }
    _memoryPrefs[key] = val;
    return val;
  }

  static double getDouble(String key, {double def}) {
    double val;
    if (_memoryPrefs.containsKey(key)) {
      val = _memoryPrefs[key];
    }
    if (val == null) {
      val = _prefs.getDouble(key);
    }
    if (val == null) {
      val = def;
    }
    _memoryPrefs[key] = val;
    return val;
  }

  static bool getBool(String key, {bool def = false}) {
    bool val;
    if (_memoryPrefs.containsKey(key)) {
      val = _memoryPrefs[key];
    }
    if (val == null) {
      val = _prefs.getBool(key);
    }
    if (val == null) {
      val = def;
    }
    _memoryPrefs[key] = val;
    return val;
  }
}