Map_Example_Dart

 import "dart:io";

void main()
{
  var cars = {
    "maruti" : 1,
    "hyundai" : 2,
    "toyota" : 3,
    "tata" : 4,
    "bmw" : 5,
    "mercedes" : 6,
    "skoda" : 7,
    "renault" : 8,
    "audi" : 9,
    "kia" : 10,
    "nissan" : 11,
    "ford" : 12,
    "mahindra" : 13,
    "jaguar" : 14,
    "honda" : 15,
    "chevrolet" : 16,
    "lamborghini" : 17,
    "bentley" : 18,
    "jeep" : 19,
    "volvo" : 20,
  };

  print("$cars\n");

  print("Enter the key : ");
  var user = stdin.readLineSync();

  if(cars.keys.contains(user))
  {
    print("\nAbove given key is Already Exist at Value ${cars[user]} in below Map\n");
    print(cars);
  }
  else
  {
    cars["$user"] = 21;
    print(cars);

    print("Please Enter another key : ");
    var otherKey = stdin.readLineSync();
    if(cars.keys.contains(otherKey))
      {
        print("Key Already Exist");
      }
    else
      {
        cars["$otherKey"] = 22;
        print(cars);
      }
  }
}