Dart list of strings

Dart Programming - Lists

A very commonly used collection in programming is an array. Dart represents arrays in the form of List objects. A List is simply an ordered group of objects. The dart:core library provides the List class that enables creation and manipulation of lists.

The logical representation of a list in Dart is given below

• test_list is the identifier that references the collection.

• The list contains in it the values 12, 13, and 14. The memory blocks holding these values are known as elements.

• Each element in the List is identified by a unique number called the index. The index starts from zero and extends up to n-1 where n is the total number of elements in the List. The index is also referred to as the subscript.

Lists can be classified as

• Fixed Length List
• Growable List

Let us now discuss these two types of lists in detail.

Fixed Length List

A fixed length lists length cannot change at runtime. The syntax for creating a fixed length list is as given below

Step 1 Declaring a list

The syntax for declaring a fixed length list is given below

var list_name = new List[initial_size]

The above syntax creates a list of the specified size. The list cannot grow or shrink at runtime. Any attempt to resize the list will result in an exception.

Step 2 Initializing a list

The syntax for initializing a list is as given below

lst_name[index] = value;

Example

Live Demovoid main[] { var lst = new List[3]; lst[0] = 12; lst[1] = 13; lst[2] = 11; print[lst]; }

It will produce the following output

[12, 13, 11]

Growable List

A growable lists length can change at run-time. The syntax for declaring and initializing a growable list is as given below

Step 1 Declaring a List

var list_name = [val1,val2,val3] --- creates a list containing the specified values OR var list_name = new List[] --- creates a list of size zero

Step 2 Initializing a List

The index / subscript is used to reference the element that should be populated with a value. The syntax for initializing a list is as given below

list_name[index] = value;

Example

The following example shows how to create a list of 3 elements.

Live Demovoid main[] { var num_list = [1,2,3]; print[num_list]; }

It will produce the following output

[1, 2, 3]

Example

The following example creates a zero-length list using the empty List[] constructor. The add[] function in the List class is used to dynamically add elements to the list.

Live Demovoid main[] { var lst = new List[]; lst.add[12]; lst.add[13]; print[lst]; }

It will produce the following output

[12, 13]

List Properties

The following table lists some commonly used properties of the List class in the dart:core library.

Sr.NoMethods & Description

1	first Returns the first element in the list.
2	isEmpty Returns true if the collection has no elements.
3	isNotEmpty Returns true if the collection has at least one element.
4	length Returns the size of the list.
5	last Returns the last element in the list.
6	reversed Returns an iterable object containing the lists values in the reverse order.
7	Single Checks if the list has only one element and returns it.