Factory constructor in Dart

main.dart

import 'dart:convert';

class Universe{
  
  String name;
  
  Universe();

  factory Universe.fromJson(Map<String,dynamic> map){
    Universe u = Universe()
    ..name = map["name"];
    return u;
  }
}

void main() {
  final jsonA = json.decode("{\"name\":\"A\"}");
  final jsonB = json.decode("{\"name\":\"B\"}");
  
  Universe u1 = Universe.fromJson(jsonA);
  Universe u2 = Universe.fromJson(jsonB);
  
  print(u1.name);  // "A"
  print(u2.name);  // "B"
}