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); 
}

{Usrname: tom, Password: pass@123}

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

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

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

{Usrname: admin, Password: admin@123}