Scala 使用枚举来匹配大小写字符串

Question

我想在这里实现的是将 astring与 an 的值进行比较enum ，我尝试使用 if

object FooType extends Enumeration {
  type FooType = Value
  val FooA = Value("FA")
  val FooB = Value("FB")
}

val x = "FA"
if (x == FooType.FooA)  //Does not match
  println("success using if without toString")
if (x == FooType.FooA.toString) //match
  println("success using if with toString")

println(FooType.FooA) //will print into "FA"

至少，当我将它与enumwithtoString方法进行比较时，它仍然运行良好。但如果我把它改成 a match case，它就会变成erroran

x match {
  case FooType.FooA.toString => println("success using match")
}

ScalaFiddle.scala:19: error: stable identifier required, but ScalaFiddle.this.FooType.FooA.toString found.
    case FooType.FooA.toString => println("success using match")
                      ^

有没有办法通过使用匹配大小写来实现这一点？

Answer 1

您必须将其转换String为FooType然后使用 match

  object FooType extends Enumeration {
    type FooType = Value
    val FooA = Value("FA")
    val FooB = Value("FB")
  }

  val x = FooType.withName("FA")

  x match {
    case FooType.FooA => println("matched")
    case _            => println("did not match")
  }