length property

int length
override

The number of objects in this list.

The valid indices for a list are 0 through length - 1.

final numbers = <int>[1, 2, 3];
print(numbers.length); // 3

Implementation

int get length => JS("int", "#.length", this);
void length=(int newLength)
override

Setting the length changes the number of elements in the list.

The list must be growable. If newLength is greater than current length, new entries are initialized to null, so newLength must not be greater than the current length if the element type E is non-nullable.

final maybeNumbers = <int?>[1, null, 3];
maybeNumbers.length = 5;
print(maybeNumbers); // [1, null, 3, null, null]
maybeNumbers.length = 2;
print(maybeNumbers); // [1, null]

final numbers = <int>[1, 2, 3];
numbers.length = 1;
print(numbers); // [1]
numbers.length = 5; // Throws, cannot add `null`s.

Implementation

set length(int newLength) {
  throw new UnsupportedError("Cannot resize immutable List.");
}