从字符串创建代数数据类型案例类

Question

我不想使用Scala Enumeration，而是希望用case类代表我的值作为代数数据类型。

  sealed abstract class MeasureType
  case object Hour extends MeasureType
  case object Day extends MeasureType
  case object Week extends MeasureType
  case object Month extends MeasureType

我想知道，是否可以从字符串创建对象，例如使用Enumeration：

MeasureType.withValue("Hour")

Answer 1

您需要使用参数上的模式匹配手动创建单独的伴随对象MeasureType并编写withValue方法。

object MeasureType {

    def withValue(val : String) : MeasureType = val match {
        case "Hour" => Hour
        case "Day" => Day
        case "Week" => Week
        case "Month" => Month
        case _ => throw new IllegalArgumentException("unrecognized name: " + val);
    } 
}