Dart List

last modified April 4, 2025

In Dart, List is an ordered collection of elements. It maintains insertion order and allows duplicate values. Lists are similar to arrays in other languages.

Lists in Dart can be either fixed-length or growable. Growable lists can change size dynamically. Lists are zero-indexed and support various operations.

Creating a List

There are several ways to create a List in Dart. The simplest is using list literals with square brackets.

main.dart

void main() { // Using list literal var fruits = [‘apple’, ‘banana’, ‘orange’]; print(fruits);

// Using List constructor var numbers = List<int>.filled(3, 0); numbers[0] = 1; numbers[1] = 2; numbers[2] = 3; print(numbers); }

The first example creates a growable list of strings. The second creates a fixed-length list initialized with zeros. We then assign values to each index.

$ dart main.dart [apple, banana, orange] [1, 2, 3]

Accessing List Elements

List elements can be accessed using index notation. Dart provides various methods for safe element access.

main.dart

void main() { var colors = [‘red’, ‘green’, ‘blue’, ‘yellow’];

// Access by index print(colors[0]); // red print(colors[3]); // yellow

// Safe access with elementAt print(colors.elementAt(2)); // blue

// First and last elements print(‘First: ${colors.first}’); print(‘Last: ${colors.last}’);

// Length print(‘Length: ${colors.length}’); }

We demonstrate different ways to access list elements. elementAt is safer than [] as it throws RangeError for invalid indices. first and last are convenient.

$ dart main.dart red yellow blue First: red Last: yellow Length: 4

Adding and Removing Elements

Growable lists support dynamic addition and removal of elements. Here are common operations.

main.dart

void main() { var numbers = [1, 2, 3];

// Adding elements numbers.add(4); numbers.addAll([5, 6]); numbers.insert(0, 0); print(‘After adding: $numbers’);

// Removing elements numbers.remove(6); numbers.removeAt(0); numbers.removeLast(); print(‘After removing: $numbers’);

// Clear all numbers.clear(); print(‘After clear: $numbers’); }

add appends a single element, while addAll adds multiple. insert places an element at a specific position. Various remove methods delete elements.

$ dart main.dart After adding: [0, 1, 2, 3, 4, 5, 6] After removing: [1, 2, 3, 4] After clear: []

List Iteration

Dart provides multiple ways to iterate through list elements. Here are the most common patterns.

main.dart

void main() { var languages = [‘Dart’, ‘Python’, ‘Java’, ‘C#’];

// for loop print(‘for loop:’); for (var i = 0; i < languages.length; i++) { print(languages[i]); }

// for-in loop print(’\nfor-in loop:’); for (var lang in languages) { print(lang); }

// forEach print(’\nforEach:’); languages.forEach((lang) => print(lang));

// map print(’\nmap:’); var upper = languages.map((lang) => lang.toUpperCase()); print(upper); }

The for loop provides index access. for-in is simpler for element access. forEach is functional style. map transforms elements to a new iterable.

$ dart main.dart for loop: Dart Python Java C#

for-in loop: Dart Python Java C#

forEach: Dart Python Java C#

map: (DART, PYTHON, JAVA, C#)

List Manipulation

Dart lists support various manipulation operations like sorting, filtering, and slicing.

main.dart

void main() { var numbers = [5, 2, 8, 1, 7, 3, 9, 4, 6];

// Sorting numbers.sort(); print(‘Sorted: $numbers’);

// Reversing var reversed = numbers.reversed.toList(); print(‘Reversed: $reversed’);

// Filtering var even = numbers.where((n) => n % 2 == 0).toList(); print(‘Even numbers: $even’);

// Sublist var middle = numbers.sublist(2, 5); print(‘Middle sublist: $middle’);

// Shuffling numbers.shuffle(); print(‘Shuffled: $numbers’); }

sort modifies the list in place. reversed returns an iterable that needs toList. where filters elements. sublist extracts a portion. shuffle randomizes order.

$ dart main.dart Sorted: [1, 2, 3, 4, 5, 6, 7, 8, 9] Reversed: [9, 8, 7, 6, 5, 4, 3, 2, 1] Even numbers: [2, 4, 6, 8] Middle sublist: [3, 4, 5] Shuffled: [5, 9, 1, 6, 3, 8, 2, 4, 7]

Spread Operator and Collection If/For

Dart supports spread operator (…) and collection if/for in list literals.

main.dart

void main() { var list1 = [1, 2, 3]; var list2 = [4, 5, 6];

// Spread operator var combined = […list1, …list2]; print(‘Combined: $combined’);

// Collection if var includeZero = true; var numbers = [if (includeZero) 0, …list1]; print(‘With optional zero: $numbers’);

// Collection for var squares = [for (var n in list2) n * n]; print(‘Squares: $squares’); }

The spread operator expands a list into individual elements. Collection if conditionally includes elements. Collection for transforms elements during list creation.

$ dart main.dart Combined: [1, 2, 3, 4, 5, 6] With optional zero: [0, 1, 2, 3] Squares: [16, 25, 36]

Best Practices

• Type Safety: Always specify list types for better code clarity.

• Growable Lists: Prefer growable lists unless fixed size is needed.

• Immutable Lists: Use List.unmodifiable for read-only lists.

• Performance: Consider LinkedList for frequent insertions/deletions.

Source

Dart List Documentation

This tutorial covered Dart’s List with practical examples demonstrating its key features and usage patterns.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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