Episode 8: Exploring Dart: Collections

Season 2: Exploring Dart

Among the essential elements that give Dart its power are the data structures known as collections. Whether you're a Dart enthusiast or a novice trying to grasp the basics, understanding Dart collections is fundamental. This article provides a comprehensive insight into Dart’s Lists, Sets, and Maps.

---

1. Embracing Lists in Dart

In many programming languages, arrays are indispensable. Similarly, in Dart, arrays manifest as List objects. More often than not, developers refer to them simply as lists.

Defining a list is straightforward:

var list = [1, 2, 3];

The type is inferred to be List<int>, signifying it will only accommodate integers.

Interestingly, Dart provides flexibility with list definitions by allowing a trailing comma, which aids in preventing copy-paste errors:

var list = [
  'Car',
  'Boat',
  'Plane',
];

Working with lists is intuitive. They follow zero-based indexing, and accessing or modifying their values is done using the subscript operator:

assert(list[1] == 2);
list[1] = 1;

For those situations requiring immutability, Dart offers the const keyword:

var constantList = const [1, 2, 3];

---

2. Navigating Sets

Sets serve as unordered collections containing unique items. That's right, no duplicates can exist in a Dart set.

Creating a set is uncomplicated:

var halogens = {'fluorine', 'chlorine', 'bromine', 'iodine', 'astatine'};

But, if you want to initiate an empty set, employ the curly braces {} with a type argument:

var names = <String>{};

Incorporating items into an existing set can be achieved using the add() or addAll() methods:

var elements = <String>{};
elements.add('fluorine');
elements.addAll(halogens);

If immutability is the goal, employ const:

final constantSet = const {
  'fluorine',
  'chlorine',
  'bromine',
  'iodine',
  'astatine',
};

---

3. Mapping with Maps

Dart’s Map is an associative collection, pairing keys with corresponding values. Each key is unique, though values can be repetitive.

Here's how you create a simple map:

var gifts = {
  'first': 'partridge',
  'second': 'turtledoves',
  'fifth': 'golden rings'
};

Alternative creation is possible using the Map constructor:

var nobleGases = Map<int, String>();
nobleGases[2] = 'helium';

Adding or retrieving key-value pairs is a breeze:

gifts['fourth'] = 'calling birds'; 
assert(gifts['first'] == 'partridge');

For constant maps, utilize the const keyword:

final constantMap = const {
  2: 'helium',
  10: 'neon',
  18: 'argon',
};

---

4. Advanced Operators: The Icing on the Cake

Dart isn’t limited to basic operations. It spices up collection manipulations with spread and control-flow operators.

The spread operator (...) provides an elegant solution for combining collections:

var list = [1, 2, 3];
var list2 = [0, ...list];

Control-flow operators like if and for enhance collection-building:

var nav = ['Home', 'Furniture', 'Plants', if (promoActive) 'Outlet'];

---

In Conclusion

Dart’s collections are versatile and efficient. By grasping the essence of Lists, Sets, and Maps, developers can harness Dart's full potential, making data manipulation more streamlined and effective. Dive into Dart and discover the realm of possibilities that await!