SharedPreferences for key-value in Flutter - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is SharedPreferences in Flutter?

SharedPreferences is a way to store small amounts of data as key-value pairs on the device. It is used for saving simple data like user settings or preferences.

beginner

How do you save a string value using SharedPreferences in Flutter?

You get an instance of SharedPreferences and then use the method setString(key, value) to save a string value with a key.

beginner

Which method do you use to read a value from SharedPreferences?

Use getString(key) for strings, getInt(key) for integers, and similar methods for other types to read stored values by their key.

intermediate

Can SharedPreferences store complex objects like lists or maps directly?

No, SharedPreferences only stores simple data types like strings, ints, doubles, bools, and string lists. For complex objects, you need to convert them to a string format like JSON.

beginner

Why is SharedPreferences suitable for storing user settings?

Because it is fast, simple, and persists data across app launches without needing a database. It is perfect for small pieces of data like user preferences.

Which method is used to save a boolean value in SharedPreferences?

A storeBool(key, value)

B saveBoolean(key, value)

C putBool(key, value)

D setBool(key, value)

The correct method to save a boolean value is setBool(key, value).

What type of data can SharedPreferences NOT store directly?

A Custom objects

B int

C String

D List of strings

SharedPreferences cannot store custom objects directly; they must be converted to strings first.

How do you get an instance of SharedPreferences in Flutter?

A SharedPreferences.instance()

B SharedPreferences.getInstance()

C SharedPreferences.create()

D SharedPreferences.new()

You use SharedPreferences.getInstance() which returns a Future of SharedPreferences.

Which of these is a correct way to read a string value from SharedPreferences?

A prefs.getString('key')

B prefs.readString('key')

C prefs.fetchString('key')

D prefs.loadString('key')

The method to read a string is getString(key), so prefs.getString('key') is correct.

What happens if you try to read a key that does not exist in SharedPreferences?

A Returns an empty string

B Throws an error

C Returns null

D Returns zero

If the key does not exist, SharedPreferences returns null.

Explain how to save and retrieve a user preference using SharedPreferences in Flutter.

Think about how you get the SharedPreferences object and then use set and get methods.

Describe the limitations of SharedPreferences and when you might need a different storage solution.

Consider what kind of data SharedPreferences can handle well and what it cannot.