How to use Map constructor to create a Map in Dart
A Map is a collection of data that is organized into key-value pairs. Any type of key and value can be used. It is a growable collection, which means it can shrink and grow in run-time.
To declare a Map we can use the Map() constructor.
Syntax
var map_name = Map();
map_name[key] = value; // initialize map
Code
The following code shows how to use the Map() constructor to create a map.
void main() {var fruits = Map();fruits[1] = 'Apple';fruits[4] = 'Avocado';fruits[2] = 'Pineapple';fruits[6] = 'Mango';fruits[3] = 'Pawpaw';print(fruits);}
Note: a Map can contain a
nullvalue.
Map properties
The properties of the Map class in the dart: core package are as follows.
Map properties
S/N | Property | Description |
1 | Keys | Returns an iterable object representing keys |
2 | Values | Returns an iterable object representing values |
3 | Length | Returns the size of the Map |
4 | isEmpty | Returns true if the Map empty |
5 | isNotEmpty | Returns true if the Map is not empty |
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