How to create an empty list in Dart

Question

I want to create an empty list for a Flutter project.

final prefs = await SharedPreferences.getInstance();
final myStringList = prefs.getStringList('my_string_list_key') ?? <empty list>;

I seem to remember there are multiple ways but one recommended way. How do I do it?

Weekender

Answer 1

There are a few ways to create an empty list in Dart. If you want a growable list then use an empty list literal like this:

[]

Or this if you need to specify the type:

<String>[]

Or this if you want a non-growable (fixed-length) list:

List.empty()

Notes

• In the past you could use List() but this is now deprecated. The reason is that List() did not initialize any members, and that isn't compatible with null safe code. Read Understanding null safety: No unnamed List constructor for more.
• Effective Dart Usage Guide

Weekender

Your are absolutely right, But if you pass "growable: true" to List.empty(growable: true) then this will too become a growable list. – Ammoniac

@KhizrAAShaikh, good point. – Weekender

Answer 2

Fixed Length List

 var fixedLengthList = List<int>.filled(5, 0);
 fixedLengthList[0] = 87;

Growable List

var growableList = [];
growableList.add(499);

For more refer Docs

Bim

These are for lists that aren't empty. – Weekender

The growable list can be empty when declared. I've edited my answer to show that. – Bim

Answer 3

I had this problem as well when I tried List.empty();, but just initializing a list to [] works and makes it append-able.

Germann

Answer 4

List documents = []; empty list of documents

List<'Student'> students = []; empty list of student object or model

Shelve