Flutter map string dynamic example – Map in Flutter

December 20, 2020

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Hi Guys, Welcome to Proto Coders Point, In this Article we will learn about map in dart programming language.

Dart Map

In Dart or any other programming language, A Map Object is a key-value pair to store string or any dynamic data.
Here, In dart map, A key & value can be of any datatype, It means that we can store any data type because a map in dart language is a dynamic collection of data/information.

In Flutter Dart, A map can be declared in 2 ways : –

Using Map Literals.
Using Map Constructor.

Declaring a map using Map Literals

To declare a map in dart you need to enclose the key-value pair in a curly bracket “{}”

Syntax
var identifier = { ‘key1′:’value1’ , ‘key2′:’value2’ , ‘key3′:’value3’, …….. };

Example

var usrMap = {"name": "Proto Coders Point ", 'Website': 'https://protocoderspoint.com/'}; 
   
print(usrMap);

output

To get/print particular key value then you can do it like this print ( usrMap[‘name’] ) this will print the value = Proto Coders Point.

Declartion of Map using Map Construtor

Using map constructor, A Map can be declared in 2 steps:

Declare Map using it constructor
Initilalize the map

Syntax

var identifier = new Map();

then, to initialize to maps with some key-value

identifier[key] = value

Example

void main() { 
  
var logincred = new Map();
  
  logincred['username']='admin';
  logincred['password']='admin@12334#';
  
  print(logincred);

}

output

Properties of Map in dart

So, to us map you need to import dart.core package

Keys : This will return all the key in map object.
Values : Wiil return all the value in map object.
length : Return the number of key-value pair length/size.
isEmpty : Will return true if Map object is empty.
IsNotEmpty : Will return true if map value is not empty.

Function of Map dart

There are some comman task performed with Map in dart:

addAll() : Used to add all key-value of some other Map Object.
clean() : Remove all data from pair.
remove() : Remove Specific date of key.
foreach : used to iterate and read alll map entires.

addAdd() : Example

void main() { 
  
 var usrMap = {"name": "Proto Coders Point ", 'Website': 'https://protocoderspoint.com/'}; 
  
  
  var map2 = {'email': 'protocoders.come'};
  
  usrMap.addAll(map2);
  
  print(usrMap);


}

output

remove() : Example

Removes Specific data of key – values from map data, it accept a key which is needed to be removed.

void main() { 
  
Map m  = { 'id': 01 ,'name': 'Rajat'};

  print("Before removing : ${m}");
  
  dynamic res = m.remove('name'); // here name is the key.
  
  print("removed data is : ${res}");
  
  
  print("After removing ${m}");

}

output

foreach : Example

By using foreach function in Map you can easily iterate and read all the maps entries.

Syntax : Map.forEach(void f(K key , V value));

void main() { 
  
var userdata = { 'name': 'Proto Coders Point', 'Website': 'https://protocoderspoint.com/'};
  
  userdata.forEach((k,v){
    print('  ${k} ${v}');
  });

}

output