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Store key-value data on disk

If you have a relatively small collection of key-values to save, you can use the shared_preferences plugin.

Normally, you would have to write native platform integrations for storing data on each platform. Fortunately, the shared_preferences plugin can be used to persist key-value data to disk on each platform Flutter supports.

This recipe uses the following steps:

  1. Add the dependency.
  2. Save data.
  3. Read data.
  4. Remove data.

1. Add the dependency

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Before starting, add the shared_preferences package as a dependency.

To add the shared_preferences package as a dependency, run flutter pub add: 

flutter pub add shared_preferences

2. Save data

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To persist data, use the setter methods provided by the SharedPreferences class. Setter methods are available for various primitive types, such as setInt, setBool, and setString.

Setter methods do two things: First, synchronously update the key-value pair in memory. Then, persist the data to disk.

dart 
// Load and obtain the shared preferences for this app. final prefs = await SharedPreferences.getInstance(); ​ // Save the counter value to persistent storage under the 'counter' key. await prefs.setInt('counter', counter);

3. Read data

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To read data, use the appropriate getter method provided by the SharedPreferences class. For each setter there is a corresponding getter. For example, you can use the getInt, getBool, and getString methods.

dart 
final prefs = await SharedPreferences.getInstance(); ​ // Try reading the counter value from persistent storage. // If not present, null is returned, so default to 0. final counter = prefs.getInt('counter') ?? 0;

Note that the getter methods throw an exception if the persisted value has a different type than the getter method expects.

4. Remove data

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To delete data, use the remove() method.

dart 
final prefs = await SharedPreferences.getInstance(); ​ // Remove the counter key-value pair from persistent storage. await prefs.remove('counter');

Supported types

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Although the key-value storage provided by shared_preferences is easy and convenient to use, it has limitations:

  • Only primitive types can be used: int, double, bool, String, and List<String>.
  • It's not designed to store large amounts of data.
  • There is no guarantee that data will be persisted across app restarts.

Testing support

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It's a good idea to test code that persists data using shared_preferences. To enable this, the package provides an in-memory mock implementation of the preference store.

To set up your tests to use the mock implementation, call the setMockInitialValues static method in a setUpAll() method in your test files. Pass in a map of key-value pairs to use as the initial values.

dart 
SharedPreferences.setMockInitialValues(<String, Object>{'counter': 2});

Complete example

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dart 
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}); ​  @override  Widget build(BuildContext context) {  return const MaterialApp(  title: 'Shared preferences demo',  home: MyHomePage(title: 'Shared preferences demo'),  );  } } ​ class MyHomePage extends StatefulWidget {  const MyHomePage({super.key, required this.title}); ​  final String title; ​  @override  State<MyHomePage> createState() => _MyHomePageState(); } ​ class _MyHomePageState extends State<MyHomePage> {  int _counter = 0; ​  @override  void initState() {  super.initState();  _loadCounter();  } ​  /// Load the initial counter value from persistent storage on start,  /// or fallback to 0 if it doesn't exist.  Future<void> _loadCounter() async {  final prefs = await SharedPreferences.getInstance();  setState(() {  _counter = prefs.getInt('counter') ?? 0;  });  } ​  /// After a click, increment the counter state and  /// asynchronously save it to persistent storage.  Future<void> _incrementCounter() async {  final prefs = await SharedPreferences.getInstance();  setState(() {  _counter = (prefs.getInt('counter') ?? 0) + 1;  prefs.setInt('counter', _counter);  });  } ​  @override  Widget build(BuildContext context) {  return Scaffold(  appBar: AppBar(title: Text(widget.title)),  body: Center(  child: Column(  mainAxisAlignment: MainAxisAlignment.center,  children: [  const Text('You have pushed the button this many times: '),  Text(  '$_counter',  style: Theme.of(context).textTheme.headlineMedium,  ),  ],  ),  ),  floatingActionButton: FloatingActionButton(  onPressed: _incrementCounter,  tooltip: 'Increment',  child: const Icon(Icons.add),  ),  );  } }

Unless stated otherwise, the documentation on this site reflects Flutter 3.35.5. Page last updated on 2025-10-28. View source or report an issue.