scala-note6-enumeration.md

Scala笔记6-枚举

使用枚举

object TrafficLightColor extends Enumeration {
  val Red, Yellow, Green = Value
}

可以指定ID和name:

object TrafficLightColor extends Enumeration {
  val Red = Value(0, "Stop") // Red.toString() to get "Stop"
  val Yellow = Value(10) // Name "Yellow"
  val Green = Value("Go") // ID 11
}

枚举的类型是TrafficLightColor.Value 而不是 TrafficLightColor 可以增加一个类型别名:

object TrafficLightColor extends Enumeration {
  type TrafficLightColor = Value
  val Red = Value(0, "Stop")
  val Yellow = Value(10)
  val Green = Value("Go")
}

object Run extends App {
  import TrafficLightColor._
  def doWhat(color: TrafficLightColor) = {
      if (color == Red) "stop"
      else if (color == Yellow) "hurry up" else "go"
  }

  // load Red
  TrafficLightColor(0) // Calls Enumeration.apply
  TrafficLightColor.withName("Red")
}