Difference between List and Map in flutter

Dart Programming - Map

The Map object is a simple key/value pair. Keys and values in a map may be of any type. A Map is a dynamic collection. In other words, Maps can grow and shrink at runtime.

Maps can be declared in two ways

• Using Map Literals
• Using a Map constructor

Declaring a Map using Map Literals

To declare a map using map literals, you need to enclose the key-value pairs within a pair of curly brackets "{ }".

Here is its syntax

var identifier = { key1:value1, key2:value2 [,..,key_n:value_n] }

Declaring a Map using a Map Constructor

To declare a Map using a Map constructor, we have two steps. First, declare the map and second, initialize the map.

The syntax to declare a map is as follows

var identifier = new Map[]

Now, use the following syntax to initialize the map

map_name[key] = value

Example: Map Literal

void main[] { var details = {'Usrname':'tom','Password':'pass@123'}; print[details]; }

It will produce the following output

{Usrname: tom, Password: pass@123}

Example: Adding Values to Map Literals at Runtime

void main[] { var details = {'Usrname':'tom','Password':'pass@123'}; details['Uid'] = 'U1oo1'; print[details]; }

It will produce the following output

{Usrname: tom, Password: pass@123, Uid: U1oo1}

Example: Map Constructor

void main[] { var details = new Map[]; details['Usrname'] = 'admin'; details['Password'] = 'admin@123'; print[details]; }

It will produce the following output

{Usrname: admin, Password: admin@123}

Note A map value can be any object including NULL.

Map Properties

The Map class in the dart:core package defines the following properties

Sr.NoProperty & 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 is an empty Map
5	isNotEmpty Returns true if the Map is an empty Map

Map - Functions

Following are the commonly used functions for manipulating Maps in Dart.

Sr.NoFunction Name & Description

1	addAll[] Adds all key-value pairs of other to this map.
2	clear[] Removes all pairs from the map.
3	remove[] Removes key and its associated value, if present, from the map.
4	forEach[] Applies f to each key-value pair of the map.