Published Mar 12, 2024
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The .addAll() method in Dart is used to add multiple elements from one list to another. This method is useful for combining the contents of multiple lists into a single list. This method does not create a new list but rather, it modifies the original list.


  • list1: The list to which another list is to be added.
  • list2: The list to be added to list1.


In the following example, there are three operations that are carried out using the .addAll() method:

  • The first operation appends a list [4, 5, 6] to an existing list nums.
  • The second operation combines the lists otherNumbers and extraNumbers and appends them to the numbers list.
  • The third operation appends a list additionalElements to a fixed-length list nonGrowableList.

Here is the example demonstrating the usage of the .addAll() method in Dart:

void main() {
final nums = <int>[1, 2, 3];
//Appends the list to the end of the 'nums' list
nums.addAll([4, 5, 6]);
List<int> numbers = [1, 2, 3];
Set<int> otherNumbers = {4, 5, 6};
List<int> extraNumbers = [7, 8, 9];
//Appends the lists 'otherNumbers' and 'extraNumbers' to the end of the 'numbers' list.
numbers.addAll([...otherNumbers, ...extraNumbers]);
List<int> nonGrowableList = List<int>.filled(3, 0);
List<int> additionalElements = [4, 5, 6];
//Appends a list to the end of a fixed-length list

The output for the above code is:

[1, 2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
Uncaught Error: Unsupported operation: addAll

Note - The .addAll() method only works on a growable list. If the list is a fixed-length list, it throws an Unsupported operation error and retains all objects.

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