Flutter Shared Preferences Example

July 26, 2020October 20, 2021 Dhrumil Shah 3 Comments flutter packages, flutter pub, local storage, save data app, shared preference android, shared preferences, shared preferences in flutter, sharedpreferences, store data

This article helps you to use shared preferences in flutter applications to store data in local. Shared Preferences store the data in a key-value pair. We can also get data in a key-value pair. You can also check out flutter storage related articles.

We can save large and complex data in local with the help of sqlite database but if we want to save small amount of data then we should use shared preferences instead of sqlite database. In SharedPreferences, we have to give just key for every single value so we can get that value using this same key.

In this example, We store and display some values with the help of shared preferences. We store user information at login screen. After submit button click, we display user information in profile screen. Now every time user opens app, we display profile page instead of login page because user already logged in.

Add below dependency in your pubspec file

shared_preferences: ^0.5.8

Store Values in Shared Preferences

You can store values in shared preferences in the form of string, integer, boolean, double and list of strings.

setStringValue(String key, String value) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
myPrefs.setString(key, value);
}

setIntegerValue(String key, int value) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
myPrefs.setInt(key, value);
}

setBooleanValue(String key, bool value) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
myPrefs.setBool(key, value);
}

setDoubleValue(String key, double value) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
myPrefs.setDouble(key, value);
}

setStringListValue(String key, List<String> value) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
myPrefs.setStringList(key, value);
}

Retrieve Values From Shared Preferences

Future<String> getStringValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.getString(key) ?? “”;
}

Future<int> getIntegerValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.getInt(key) ?? 0;
}

Future<bool> getBooleanValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.getBool(key) ?? false;
}

Future<double> getDoubleValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.getDouble(key) ?? 0;
}

Future<List<String>> getStringListValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.getStringList(key);
}

Check Key is Stored or Not

Future<bool> containsKey(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.containsKey(key);
}

Remove Specific Value

removeValue(String key) async {
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.remove(key);
}

Remove All Data From Shared Preferences

removeAll() async{
SharedPreferences myPrefs = await SharedPreferences.getInstance();
return myPrefs.clear();
}

Final Code

my_shared_preferences.dart

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<String> getStringValue(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.getString(key) ?? "";
  }

  setIntegerValue(String key, int value) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    myPrefs.setInt(key, value);
  }

  Future<int> getIntegerValue(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.getInt(key) ?? 0;
  }

  setBooleanValue(String key, bool value) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    myPrefs.setBool(key, value);
  }

  Future<bool> getBooleanValue(String key) async {
    SharedPreferences myPrefs = await SharedPreferences.getInstance();
    return myPrefs.getBool(key) ?? false;
  }

  Future<bool> 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();
  }

}

main.dart

import 'package:flutter/material.dart';
import 'my_shared_preferences.dart';
import 'login.dart';
import 'profile.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return MyAppState();
  }
}

class MyAppState extends State<MyApp> {
  // This widget is the root of your application.

  bool isLoggedIn = false;

  MyAppState() {
    MySharedPreferences.instance
        .getBooleanValue("loggedin")
        .then((value) => setState(() {
              isLoggedIn = value;
            }));
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        title: 'Flutter Demo',
        home: isLoggedIn ? Profile() : Login());
  }
}

login.dart

import 'package:flutter/material.dart';
import 'my_shared_preferences.dart';
import 'profile.dart';

class Login extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return LoginState();
  }
}

class LoginState extends State<Login> {
  TextEditingController controllerEmail = new TextEditingController();
  TextEditingController controllerUserName = new TextEditingController();
  TextEditingController controllerPassword = new TextEditingController();

  @override
  Widget build(BuildContext context) {

    final formKey = GlobalKey<FormState>();

    // TODO: implement build
    return SafeArea(
      child: Scaffold(
          body: SingleChildScrollView(
        child: Container(
          margin: EdgeInsets.all(25),
          child: Form(
            key: formKey,
            autovalidate: false,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Row(
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: <Widget>[
                    Text("Email Id:", style: TextStyle(fontSize: 18)),
                    SizedBox(width: 20),
                    Expanded(
                      child: TextFormField(
                        controller: controllerEmail,
                        decoration: InputDecoration(
                          hintText: "Please enter email",
                        ),
                        keyboardType: TextInputType.emailAddress,
                        validator: (value) {
                          if (value.trim().isEmpty) {
                            return "Email Id is Required";
                          }
                        },
                      ),
                    )
                  ],
                ),
                SizedBox(height: 60),
                Row(
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: <Widget>[
                    Text("UserName:", style: TextStyle(fontSize: 18)),
                    SizedBox(width: 20),
                    Expanded(
                      child: TextFormField(
                          decoration: InputDecoration(
                            hintText: "Please enter username",
                          ),
                          validator: (value) {
                            if (value.trim().isEmpty) {
                              return "UserName is Required";
                            }
                          },
                          controller: controllerUserName),
                    )
                  ],
                ),
                SizedBox(height: 60),
                Row(
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: <Widget>[
                    Text("Password:", style: TextStyle(fontSize: 18)),
                    SizedBox(width: 20),
                    Expanded(
                      child: TextFormField(
                          decoration: InputDecoration(
                            hintText: "Please enter password",
                          ),
                          obscureText: true,
                          validator: (value) {
                            if (value.trim().isEmpty) {
                              return "Password is Required";
                            }
                          },
                          controller: controllerPassword),
                    )
                  ],
                ),
                SizedBox(height: 100),
                SizedBox(
                  width: 150,
                  height: 50,
                  child: RaisedButton(
                    color: Colors.grey,
                    child: Text("Submit",
                        style: TextStyle(color: Colors.white, fontSize: 18)),
                    onPressed: () {
                      if(formKey.currentState.validate()) {
                        var getEmail = controllerEmail.text;
                        var getUserName = controllerUserName.text;
                        var getPassword = controllerPassword.text;

                        MySharedPreferences.instance
                            .setStringValue("email", getEmail);
                        MySharedPreferences.instance
                            .setStringValue("username", getUserName);
                        MySharedPreferences.instance
                            .setStringValue("password", getPassword);
                        MySharedPreferences.instance
                            .setBooleanValue("loggedin", true);

                        Navigator.pushReplacement(
                          context,
                          MaterialPageRoute(builder: (_) => Profile()),
                        );
                      }
                    },
                  ),
                )
              ],
            ),
          ),
        ),
      )),
    );
  }
}

profile.dart

import 'package:flutter/material.dart';
import 'my_shared_preferences.dart';
import 'login.dart';

class Profile extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return ProfileState();
  }
}

class ProfileState extends State<Profile> {
  String email = "";
  String username = "";

  ProfileState() {
    MySharedPreferences.instance
        .getStringValue("email")
        .then((value) => setState(() {
              email = value;
            }));
    MySharedPreferences.instance
        .getStringValue("username")
        .then((value) => setState(() {
              username = value;
            }));
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return SafeArea(
      child: Scaffold(
        body: Center(
          child: Container(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text(
                  "Hello, " + username,
                  style: TextStyle(fontSize: 35, fontWeight: FontWeight.bold),
                ),
                SizedBox(height: 30),
                Text(
                  email,
                  style: TextStyle(fontSize: 25, fontWeight: FontWeight.bold),
                ),
                SizedBox(height: 80),
                SizedBox(
                  width: 150,
                  height: 50,
                  child: RaisedButton(
                      color: Colors.grey,
                      child: Text("Logout",
                          style: TextStyle(color: Colors.white, fontSize: 18)),
                      onPressed: () {
                        MySharedPreferences.instance.removeAll();
                        Navigator.pushReplacement(context,
                            MaterialPageRoute(builder: (_) => Login()));
                      }),
                )
              ],
            ),
          ),
        ),
      ),
    );
  }
}