# Local Storage (Flutter)

> SharedPreferences, flutter_secure_storage, path_provider, files, security best practices

- 20 interview questions
- Junior
- [Interview Questions: Flutter](https://sharpskill.dev/en/technologies/flutter/interview-questions.md)

## 1. Which package should be used to store simple key-value pairs persistently in a Flutter application?

**Answer**

SharedPreferences is the standard package for storing simple key-value data persistently in Flutter. It uses NSUserDefaults on iOS and SharedPreferences on Android. This package is ideal for user preferences, application settings, or small amounts of non-sensitive data.

## 2. How to obtain a SharedPreferences instance in Flutter?

**Answer**

SharedPreferences.getInstance() returns a Future that resolves to the single SharedPreferences instance. This asynchronous method loads preferences from native storage. It is recommended to call this method once and reuse the instance to avoid multiple loads.

## 3. What data types can be stored with SharedPreferences?

**Answer**

SharedPreferences only supports primitive types: int, double, bool, String, and List<String>. To store complex objects, they must be serialized to JSON String and then deserialized when reading. This limitation is due to the underlying native implementation on iOS and Android.

## 17 more questions available

- Which method should be used to save a boolean value with SharedPreferences?
- What does prefs.getString('key') return if the key does not exist in SharedPreferences?

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