Enumerations (Enums) trong Dart

enum Color { red, green, blue }
 
enum DayOfWeek {
  monday,
  tuesday,
  wednesday,
  thursday,
  friday,
  saturday,
  sunday
}
 
void main() {
  var today = DayOfWeek.friday;
  print(today);  // DayOfWeek.friday
}

void main() {
  // Lấy tất cả giá trị
  print(Color.values);  // [Color.red, Color.green, Color.blue]
  
  // Index
  print(Color.red.index);    // 0
  print(Color.green.index);  // 1
  
  // Name
  print(Color.red.name);  // red
}

enum Status { pending, approved, rejected }
 
void handleStatus(Status status) {
  switch (status) {
    case Status.pending:
      print('Đang chờ xử lý');
      break;
    case Status.approved:
      print('Đã duyệt');
      break;
    case Status.rejected:
      print('Từ chối');
      break;
  }
}

enum Vehicle {
  car(wheels: 4, maxSpeed: 200),
  bike(wheels: 2, maxSpeed: 120),
  truck(wheels: 6, maxSpeed: 100);
  
  final int wheels;
  final int maxSpeed;
  
  const Vehicle({required this.wheels, required this.maxSpeed});
  
  String get description => '$name has $wheels wheels';
}
 
void main() {
  print(Vehicle.car.wheels);       // 4
  print(Vehicle.bike.description); // bike has 2 wheels
}

enum Priority {
  low(1),
  medium(2),
  high(3),
  critical(4);
  
  final int level;
  const Priority(this.level);
  
  bool isHigherThan(Priority other) => level > other.level;
  
  String get emoji {
    switch (this) {
      case Priority.low: return '🟢';
      case Priority.medium: return '🟡';
      case Priority.high: return '🟠';
      case Priority.critical: return '🔴';
    }
  }
}

abstract class Describable {
  String describe();
}
 
enum PizzaSize implements Describable {
  small(8),
  medium(12),
  large(16);
  
  final int inches;
  const PizzaSize(this.inches);
  
  @override
  String describe() => '$name ($inches inches)';
}

enum Color { red, green, blue }
 
void main() {
  // String to Enum
  String colorName = 'red';
  Color color = Color.values.firstWhere(
    (e) => e.name == colorName,
    orElse: () => Color.red,
  );
  
  // Hoặc với Dart 2.17+
  Color? parsed = Color.values.asNameMap()[colorName];
}