List<E> constructor Null safety

  1. @Deprecated("Use a list literal, [], or the List.filled constructor instead")
  1. [int? length]

Creates a list of the given length.

NOTE: This constructor cannot be used in null-safe code. Use List.filled to create a non-empty list. This requires a fill value to initialize the list elements with. To create an empty list, use [] for a growable list or List.empty for a fixed length list (or where growability is determined at run-time).

The created list is fixed-length if length is provided.

var fixedLengthList = List(3);
fixedLengthList.length;     // 3
fixedLengthList.length = 1; // Error

The list has length 0 and is growable if length is omitted.

var growableList = List();
growableList.length; // 0;
growableList.length = 3;

To create a growable list with a given length, for a nullable element type, just assign the length right after creation:

List<SomeNullableType> growableList = []..length = 500;

For a non-nullable element type, an alternative is the following:

List<int> growableList = List<int>.filled(500, 0, growable: true);

The length must not be negative or null, if it is provided.

If the element type is not nullable, length must not be greater than zero.


@Deprecated("Use a list literal, [], or the List.filled constructor instead")
external factory List([int? length]);