Lära List in Dart | Variables and Data Types in Dart

Definition

A List in Dart is a built-in data type that represents an ordered collection of elements. Each element in a List usually has the same data type, such as integers, floating-point numbers, strings, or other objects.

Lists are useful for:

Storing data about a group of related items, such as a shopping list, to-do list, or contact list.
Tracking sequences of events, such as a history log or a list of steps needed to complete a task.

They help keep related information organized and easy to access.

Syntax

Let's look at the scheme of creating a List:

List<elements_type> list_name = [element_1, element_2];

List: command to create a list;
<elements_type>: the data type for values will be stored in the middle of the list;
list_name: list name;
[element_1, element_2]: commas (,) separate the list elements.

main.dart


              1
            
List<int> numbers = [1, 2, 3, 4, 5];

List of integer numbers;
<int> type elements from List.

Adding Items

Let's add a value to the already existing list of numbers.

main.dart


              123456
            
void main() {
  List<int> numbers = [111, 22, 32];
  print(numbers); // Output [111, 22, 32]
  numbers.add(6); // Adding an item to a list
  print(numbers); // Output [111, 22, 32, 6]
}

numbers.add(6);

The expression numbers.add(6); calls the add() method on the variable numbers, adding the value 6 to it.

Deleting Items

list_name.remove(element)

The expression list_name.remove(element) calls the remove() method on the variable, deleting the first occurrence of the specified value.

main.dart


              123456
            
void main() {
  List<int> numbers = [11, 22, 23];
  print(numbers); // [11, 22, 23]
  numbers.remove(22);
  print(numbers); // [11, 23]
}

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Avsnitt 2. Kapitel 6

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Definition

Lists are useful for:

Storing data about a group of related items, such as a shopping list, to-do list, or contact list.
Tracking sequences of events, such as a history log or a list of steps needed to complete a task.

They help keep related information organized and easy to access.

Syntax

Let's look at the scheme of creating a List:

List<elements_type> list_name = [element_1, element_2];

List: command to create a list;
<elements_type>: the data type for values will be stored in the middle of the list;
list_name: list name;
[element_1, element_2]: commas (,) separate the list elements.

main.dart


              1
            
List<int> numbers = [1, 2, 3, 4, 5];

List of integer numbers;
<int> type elements from List.

Adding Items

Let's add a value to the already existing list of numbers.

main.dart


              123456
            
void main() {
  List<int> numbers = [111, 22, 32];
  print(numbers); // Output [111, 22, 32]
  numbers.add(6); // Adding an item to a list
  print(numbers); // Output [111, 22, 32, 6]
}

numbers.add(6);

The expression numbers.add(6); calls the add() method on the variable numbers, adding the value 6 to it.

Deleting Items

list_name.remove(element)

The expression list_name.remove(element) calls the remove() method on the variable, deleting the first occurrence of the specified value.

main.dart


              123456
            
void main() {
  List<int> numbers = [11, 22, 23];
  print(numbers); // [11, 22, 23]
  numbers.remove(22);
  print(numbers); // [11, 23]
}

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 2. Kapitel 6