Enumerated annotation type in Kotlin

Question

In java I can define enumerated annotation type like this (from here)

// Constants
public static final String WINTER = "Winter";
public static final String SPRING = "Spring";
public static final String SUMMER = "Summer";
public static final String FALL = "Fall";

// Declare the @ StringDef for these constants:
@StringDef({WINTER, SPRING, SUMMER, FALL})
@Retention(RetentionPolicy.SOURCE)
public @interface Season {}

What is Kotlin version of this code?

I have a problem when using this (straight conversion using IDE)

// Constants
private const val WINTER = "Winter"
private const val SPRING = "Spring"
private const val SUMMER = "Summer"
private const val FALL = "Fall"

// Declare the @ StringDef for these constants:
@StringDef(WINTER, SPRING, SUMMER, FALL)
@Retention(AnnotationRetention.SOURCE)
annotation class Season

as I cannot access e.g. Season.WINTER

Where are you trying to access to Season.Winter?. If it is a private constant, you will not be able to access it from outside the class. — Miguel Isla, Mar 07 '19 at 09:50
Also you can try [this solution](https://stackoverflow.com/questions/35976002/how-to-use-android-support-typedef-annotations-in-kotlin/38537175#38537175) — Miguel Isla, Mar 07 '19 at 09:51
:D @MiguelIsla, let me check if this is the reason that causes problems — svkaka, Mar 07 '19 at 09:56

shkschneider · Answer 1 · 2019-03-07T09:42:47.287

2

In Kotlin you're better off using enum class. I had many problems converting @IntDef and @StringDef usages in Kotlin.

enum class Season constructor(val value: String) {
  WINTER("Winter"),
  SPRING("Spring"),
  SUMMER("Summer"),
  FALL("Fall");

  override fun toString(): String = value
}

edited Mar 07 '19 at 09:42

answered Mar 07 '19 at 09:22

shkschneider

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isn't name final? Also, I am working on a library and I think it's still recommended to use enum annotation type instead of enums, so I would like to stick with that – svkaka Mar 07 '19 at 09:29
I made it `val` so it's final yes, but that's up to you. Now if you don't want to use enum.. – shkschneider Mar 07 '19 at 09:36
I mean IDE shows me an error "name in Enum is final and can't be overriden" – svkaka Mar 07 '19 at 09:38
before adding override it was "name hides member of supertype and needs 'override' modifier" – svkaka Mar 07 '19 at 09:39
Yeah ok, I was making that code out of my head, I fixed it. `name` was indeed reserved ;) – shkschneider Mar 07 '19 at 09:43

Enumerated annotation type in Kotlin

1 Answers1