Scala using enum to string in match case

Question

what I want to achieve in here is to compare a string with a value of an enum first, I tried it using 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"

at least, it still working well when I compare it to the enum with toString method. but if I change it to a match case, it would turn into an error instead

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")
                      ^

is there any way to achieve this by using match case?

Anish B. · Accepted Answer · 2023-08-28 07:12:30Z

5

You have to convert the String into FooType and then use 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")
  }

edited Aug 28, 2023 at 7:12

Anish B.

17.2k4 gold badges29 silver badges53 bronze badges

answered Apr 29, 2020 at 7:32

Ivan Stanislavciuc

7,27517 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Pedro Correia Luis · Accepted Answer · 2020-04-29 07:46:55Z

2

You are converting a type in your match case, that is not allowed, you can do something like this:

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

val x = "FA"

x match {
    case str if str == FooType.FooA.toString => println("success using match")
    case _            => println("did not match")
  }

or you can do something similar to what @Ivan Stanislavciuc suggested

x match {
    case str if FooType.withName(str) == FooType.FooA => println("success using match")
    case _            => println("did not match")
  }

answered Apr 29, 2020 at 7:46

Pedro Correia Luis

1,0857 silver badges16 bronze badges

Collectives™ on Stack Overflow

Scala using enum to string in match case

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related