tea_final.dart

class Tea {
  final String teaBag;
  Milk? milk;

  Tea(this.teaBag, [this.milk]);

  String getFullName() {
    if (milk != null) {
      return "$teaBag 밀크티";
    }

    return "$teaBag 티";
  }
}

class Milk {
  String name = "서울우유";
  int amount = 100;
}

void main() {
  var tea = Tea('얼그레이');
  print(tea.getFullName()); // 얼그레이 티

  // tea.teaBag = "캐모마일"; // Error: The setter 'teaBag' isn't defined for the class 'Tea'.
  tea.milk = Milk();
  print(tea.getFullName()); // 얼그레이 밀크티
}