Scala pattern match against a Java enum type

Question

I have a Java enum type that has some Strings and I want to pattern match against in. Here is what I have done so far:

public enum MyEnum {
  YEAR, MONTH;
}

In my scala function, I do the following:

timePeriod.toUpperCase match {
  case MyEnum.YEAR.name => doSomething
  case MyEnum.MONTH.name => doSomething
}

When I compile, I get the following error:

stable identifier required, but YEAR.name found

It is not informative enough for me to understand the root cause of the error. Any ideas?

Answer 1

You can't have method calls as clauses in a match, because the result of the method may differ. We know in this case it doesn't but there's no way to indicate to the compiler that a method call is constant.

You could do this:

  timePeriod.toUpperCase match {
    case period if period == MyEnum.YEAR.name =>
    case period if period == MyEnum.MONTH.name =>
  }

Which is a bit more verbose. Someone else may have a shorter and better suggestion.