How to implement Shared preferences in Flutter?

Implement Shared Preferences in Flutter

Step 1:–

Run this command in the terminal

flutter pub add shared_preferences

OR

shared_preferences:  #use latest version  and add in pubspec.yaml file

Step 2:-

store String form data in SharedPreferences

storeDataInSharedPref(data) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    //Note here we use key1 as a unique key which store data in sharedPreferences
    await prefs.setString('key1', data); //
  }

Step 3:-

Fetch String form of data based on the Unique Key

Note: always use unique key to store data example access_token , user_password, credit_card_number etc

  Future<String?>? fetchSharedPrefData(key) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    //Note here we use pass key
    var value = await prefs.getString(key); //
    // print("value  >>>>>  $value");
    return value;
  }

Step 4:-

Now in this container we use Shared Preferences where user can store and fetch data through elevated button

Note: here we are using setState(), according to your state management you can use other options which refresh the variable or widget information

Container(
            padding: EdgeInsets.all(16.0),
            child: Column(
              children: [
                TextFormField(
                  controller: controller,
                  decoration: InputDecoration(
                    hintText: 'Store data',
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(10.0),
                    ),
                  ),
                ),
                const SizedBox(
                  height: 5,
                ),
                const SizedBox(
                  height: 10,
                ),
                ElevatedButton(
                  child: const Text(
                    "Save in SharedPref",
                  ),
                  onPressed: () async {
                    if (controller.text != null) {
            //Here we store Shared Preferences          storeDataInSharedPref(controller.text);
                    }
                  },
                ),
                const SizedBox(
                  height: 15,
                ),
                ElevatedButton(
                    onPressed: () async {
                      //Here we fetch Shared Preferences fetchSharedPrefData('key1')?.then((value) {
                        setState(() {
                          newValue = value.toString();
                        });
                      });
                      // print("newValue   $newValue");
                    },
                    child: const Text('Show Stored daata')),
                SizedBox(
                  height: 5,
                ),
                Text(newValue.toString())
              ],
            ),
          )

Full Code of implement Sharedpreferences in Flutter

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'ResearchThinker',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MySharedPrefExample(),
    );
  }
}

class MySharedPrefExample extends StatefulWidget {
  const MySharedPrefExample({Key? key}) : super(key: key);

  @override
  State<MySharedPrefExample> createState() => _MySharedPrefExampleState();
}

class _MySharedPrefExampleState extends State<MySharedPrefExample> {
  TextEditingController controller = TextEditingController();
  var newValue = '';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('ResearchThinker Flutter Examples'),
        ),
        body: SingleChildScrollView(
          child: Container(
            padding: EdgeInsets.all(16.0),
            child: Column(
              children: [
                TextFormField(
                  controller: controller,
                  decoration: InputDecoration(
                    hintText: 'Store data',
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(10.0),
                    ),
                  ),
                ),
                const SizedBox(
                  height: 5,
                ),
                const SizedBox(
                  height: 10,
                ),
                ElevatedButton(
                  child: const Text(
                    "Save in SharedPref",
                  ),
                  onPressed: () async {
                    if (controller.text != null) {
                 //Here we store Shared Preferences      storeDataInSharedPref(controller.text);
                    }
                  },
                ),
                const SizedBox(
                  height: 15,
                ),
                ElevatedButton(
                    onPressed: () async {
                      //Here we fetch Shared Preferences fetchSharedPrefData('key1')?.then((value) {
                        setState(() {
                          newValue = value.toString();
                        });
                      });
                      // print("newValue   $newValue");
                    },
                    child: const Text('Show Stored daata')),
                SizedBox(
                  height: 5,
                ),
                Text(newValue.toString())
              ],
            ),
          ),
        ),
      ),
    );
  }

//Below functions used for Storing and fetching shared preferences
  storeDataInSharedPref(data) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    //Note here we use key1 as a unique key which store data in sharedPreferences
    await prefs.setString('key1', data); //
  }

  Future<String?>? fetchSharedPrefData(key) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    //Note here we use pass key
    var value = await prefs.getString(key); //
    // print("value    $value");
    return value;
  }
}

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