How to Create a List in Dart

In Dart, a List is an ordered collection of items that can contain duplicate elements. Lists are indexed, meaning you can access elements by their position in the list. Dart provides several ways to create lists, and they can be mutable (modifiable) or immutable (fixed-length).

1. Creating a Mutable List

A mutable list can be modified after it is created. You can add, remove, or change elements in a mutable list.

Example of Creating a Mutable List

void main() {
    // Creating a mutable list of integers
    List<int> numbers = [1, 2, 3, 4, 5];

    // Adding an element
    numbers.add(6);

    // Removing an element
    numbers.remove(3);

    // Accessing elements
    print(numbers[0]); // Output: 1

    // Iterating through the list
    for (var number in numbers) {
        print(number); // Output: 1 2 4 5 6
    }
}
</int>

In this example, we create a mutable list of integers, add an element, remove an element, access an element by its index, and iterate through the list to print its contents.

2. Creating a Fixed-Length List

A fixed-length list cannot be modified after it is created. You cannot add or remove elements, but you can change the values of existing elements.

Example of Creating a Fixed-Length List

void main() {
    // Creating a fixed-length list of integers
    List<int> fixedNumbers = List.filled(5, 0); // List of length 5, initialized with 0

    // Changing values
    fixedNumbers[0] = 10;
    fixedNumbers[1] = 20;

    // Accessing elements
    print(fixedNumbers[0]); // Output: 10

    // Iterating through the fixed-length list
    for (var number in fixedNumbers) {
        print(number); // Output: 10 20 0 0 0
    }

    // Attempting to add an element will result in an error
    // fixedNumbers.add(30); // Uncommenting this line will cause an error
}
</int>

In this example, we create a fixed-length list of integers initialized with zeros. We change some values and iterate through the list to print its contents. Attempting to add an element to a fixed-length list will result in an error.

3. Creating a List Using Constructors

You can also create a list using the List constructor. This is useful when you want to create an empty list or a list with a specific length.

Example of Creating a List Using Constructors

void main() {
    // Creating an empty list
    List<string> emptyList = List<string>.empty();

    // Creating a list with a specific length
    List<string> stringList = List<string>.filled(3, 'default');

    // Adding elements to the empty list
    emptyList.add('Hello');
    emptyList.add('Dart');

    // Accessing elements
    print(emptyList[0]); // Output: Hello
    print(stringList);    // Output: [default, default, default]
}
</string></string></string></string>

In this example, we create an empty list of strings and a list of strings with a specific length initialized with the value 'default'. We add elements to the empty list and print the contents of both lists.

4. Conclusion

Creating lists in Dart is straightforward and flexible. You can create mutable or fixed-length lists, use constructors, and manipulate the contents as needed. Understanding how to create and work with lists is essential for managing collections of data effectively in Dart applications.