void main() {
  var myMap = Map();
  print("************ Before adding data in Map ************");
  print(myMap);

//  Adding value to Map
  myMap["id"] = "jay";
  myMap["password"] = "1234";
  myMap["country"] = "India";
  print("************ After adding data in Map ************");
  print(myMap);
}

Output
************ Before adding data in Map ************
{}
************ After adding data in Map ************
{id: jay, password: 1234, country: India}