Learn Dart Collections

In Dart, collections are objects used to store multiple values in an organized and iterable manner. Dart provides built-in support for various types of collections, including lists, sets, maps, and queues. These collection types offer different characteristics and are suited for different use cases.

---

Lists

Ordered collection of elements.
Allows duplicate elements.
Accessed by index.

List< int> numbers = [1, 2, 3, 4, 5];
List< String> names = ['Alice', 'Bob', 'Charlie'];

---

Set

Unordered collection of unique elements.
Does not allow duplicate elements.
Efficient for membership tests.

Set< int> uniqueNumbers = {1, 2, 3, 4, 5};
Set< String> uniqueNames = {'Alice', 'Bob', 'Charlie'};

---

Map

Collection of key-value pairs.
Keys must be unique.
Accessed by key.

Map ages = {'Alice': 30, 'Bob': 25, 'Charlie': 35};
Map students = {1: 'Alice', 2: 'Bob', 3: 'Charlie'};

Queue:

Ordered collection supporting efficient insertion and removal operations at both ends.
Useful for implementing FIFO (First-In-First-Out) data structures.

import 'dart:collection';
Queue queue = Queue();
queue.addAll([1, 2, 3]);
queue.removeFirst();
queue.removeLast();

Common Operations on Collections:

Adding Elements:

Lists: list.add(value), list.addAll(otherList).
Sets: set.add(value).
Maps: map[key] = value

---

Removing Elements

Lists: list.remove(value), list.removeAt(index).
Sets: set.remove(value).
Maps: map.remove(key).

---

Iterating :

Using for-in loops or methods like forEach().

List< int > numbers = [1, 2, 3, 4, 5];
numbers.forEach((number) => print(number));
Set< String > names = {'Alice', 'Bob', 'Charlie'};
for (var name in names) {
print(name);
}
Map< String, int > ages = {'Alice': 30, 'Bob': 25, 'Charlie': 35};
ages.forEach((key, value) => print('$key is $value years old'));

---

Immutable Collections:

Dart also provides immutable versions of collections using the const keyword, which prevents modifications after initialization.

var constantList = const [1, 2, 3];
var constantSet = const {'Alice', 'Bob', 'Charlie'};
var constantMap = const {'Alice': 30, 'Bob': 25, 'Charlie': 35};

---

Next