skyState method Null safety

Implementation

static String skyState(String sky, String pty) {
  final int ptyInt = int.parse(pty);
  final int skyInt = int.parse(sky);

  switch (ptyInt) {
    case 1:
      return "비";
    case 2:
      return "눈/비";
    case 3:
      return "눈";
    case 4:
      return "소나기";
    default:
      switch (skyInt) {
        case 6:
        case 7:
        case 8:
          return "구름많음";
        case 9:
        case 10:
          return "흐림";
        default:
          return "맑음";
      }
  }
}