How to Merge 2 Lists in Dart

This article shows you a couple of different ways to join 2 lists in Dart. You will learn each method through an example.

Using Addition (+) Operator

Example:

void main() {
  final List list1 = [1, 2, 3];
  final List list2 = [4, 5, 6];
  final List list3 = list1 + list2;
  print(list3);
}

Output:

[1, 2, 3, 4, 5, 6]

In my opinion, this approach is the most intuitive.

Using List addAll() method

The List class of Dart provides the addAll() method that helps you easily join 2 lists together.

Example:

void main() {
  List listA = [1, 2, 3];
  List listB = [4, 5, 6];
  listA.addAll(listB);
  print(listA);
  
  List<String> listC = ['Dog', 'Cat'];
  List<String> listD = ['Bear', 'Tiger'];
  listC.addAll(listD);
  print(listC);
}

Output:

[1, 2, 3, 4, 5, 6]
[Dog, Cat, Bear, Tiger]

Using Spread Operator

This approach is very concise.

Example:

void main() {
  final List list1 = ['A', 'B', 'C'];
  final List list2 = ['D', 'E', 'F'];
  final List list3 = [...list1, ...list2];
  print(list3);
}

Output:

[A, B, C, D, E, F]

Wrapping Up

We’ve walked through a few approaches to combining lists in Dart. This knowledge is very helpful when working with data-driven applications. If you’d like to explore more about Dart and Flutter, take a look at the following articles:

• Dart: Convert Class Instances (Objects) to Maps and Vice Versa
• How to Flatten a Nested List in Dart
• Flutter & Dart: 3 Ways to Generate Random Strings
• Using Chip widget in Flutter: Tutorial & Examples
• Flutter: SliverGrid example
• Flutter & Dart: How to Check if a String is Null/Empty

You can also check out our Flutter category page or Dart category page for the latest tutorials and examples.