How to use maps in DART

Maps in DART

DART maps is an object that associates keys to value. In DART maps is an interface designed to manipulate a collection of keys which point to value.

• Map literal
  
  In map literal every key must be a string. If you want every key does not a string , then use map constructor.

Example of map literal

var map={keys :values}; // map literal

• Map constructor
  
  Map constructor can be string, a number or any other object.

Example of map constructor

var map = new Map(); map[1]="value"; map[2]="value";

 

You can add a new value in map like java script.
 

map["key"]="value";

Methods in maps

There are following maps method:

• Length method
  
  By the help of this method you can find out maps length.

Syntax of length method
 

map.length;

• Remove method
  
  If you want to remove of any value from map, then use remove().

Syntax of remove method
 

map.remove(key);

• Copy method
  
  If you want to copies a map to another then use Map.from();

Syntax of copy method
 

var copymap=new Map.Fromcopy(mapname);

• Empty method
  
  If you want to check a map is empty or not then use isEmpty().

Syntax of  empty  method
 

mapname.isEmpty();

 

•  Containkey method:

               If you want to check a key is present in maps or not use containsKey();
 

Syntax of  containkey  method
 

mapname.containsKey();

Example of Maps
 

void main() { var mapconst = new Map(); mapconst[1]="Google"; mapconst[2]="1.o.1"; var empty = {}; for(int i=1;i<=2;i++){   print(mapconst[i]);  } var mapliteral = {"first": "c-sharpcorner", "second": "dotnetheaven"}; var values = mapliteral.getValues(); values.forEach((v) => print(v)); int len=mapliteral.length; print("The length of mapliteral is :${len}"); print(mapliteral.remove('first')); var copymap = new Map.from(mapconst); for(int i=1;i<=2;i++){   print(copymap[i]);  } print(mapconst.isEmpty()); print(empty.isEmpty()); print(mapliteral.containsKey("second")); //mapliteral.containsKey("second"); }

Output: