Dart Basic- Lists

Lists in Dart

The dart:core library provides the List class that enables the creation and manipulation of lists. Lists are a collection of objects, and they can be classified into two types:

• Fixed Length List
• Growable List.

Fixed Length List

A fixed-length list is a list whose length cannot be changed after initialization. The syntax for creating a fixed-length list is as follows:

Declaring a list

The syntax for declaring a fixed-length list is as given below:

List list_name = List(initial_size);

The above syntax creates a list of the specified size, and all the elements in the list are initialized to null. The list cannot grow or shrink at runtime. Any attempt to resize the list will result in an exception.

Initializing a list

The syntax for initializing a fixed-length list is as follows:

list_name[index] = value;

Example:

void main() {
    List lst = List(3);
    lst[0] = 12;
    lst[1] = 13;
    lst[2] = 11;
    print(lst);
}

Output:

[12, 13, 11]

Growable List

A growable list is a list whose length can change at runtime. The syntax for declaring and initializing a growable list is as follows:

Declaring a List

The syntax for declaring a growable list is as given below:

List list_name = [val1, val2, val3, …];

OR

List list_name = List();

The above syntax creates a list of size zero.

Initializing a List

The syntax for initializing a growable list is as given below:

list_name[index] = value;

Example:

void main() {
    List lst = [];
    lst.add(12);
    lst.add(13);
    lst.add(11);
    print(lst);
}

Output:

[12, 13, 11]

List Properties

The List class in Dart provides several properties for working with lists. Here are some of the commonly used properties:

List Properties

Example:

void main() {
  // create a list of numbers
  var numbers = [1, 2, 3, 4, 5];

  // access the first and last elements
  print(numbers.first); // prints 1
  print(numbers.last); // prints 5

  // check if the list is empty or not
  print(numbers.isEmpty); // prints false
  print(numbers.isNotEmpty); // prints true

  // get the length of the list
  print(numbers.length); // prints 5

  // get an iterable object containing the list's values in reverse order
  var reversedNumbers = numbers.reversed;
  print(reversedNumbers); // prints (5, 4, 3, 2, 1)

  // check if the list has only one element and return it
  print([6].single); // prints 6
}

Output:

1
5
false
true
5
(5, 4, 3, 2, 1)
6