Is there a way to get something like this working ...

# getting-started

[Colton Idle]

Is there a way to get something like this working to go from a string to an enum?

val banana = Type.getEnumFor("one")

enum class Type(val stringly: String) {
    A("one"),
    B("two"),
    C("three")
}

and so banana would be == Type.A?

[Paul Griffith]

https://pl.kotl.in/X6_ll6mIC

[ephemient]

Type.valueOf("one")
enumValueOf<Type>("one")

built-in

[ephemient]

oh that's by enum entry name... yeah if you want your own you need to build your own

[Colton Idle]

Interesting... so if my names line up 1:1 then I cannnn have it work? hm

[ephemient]

val valuesByStringly = values.associateBy { it.stringly }
valuesByStringly["one"]

[ephemient]

yes

[Paul Griffith]

and, yeah, you probably want to cache the associative map instead of calling values() (iterates a new array each time) and iterating the list
in practice unless this is called in a really hot loop it’s likely not going to matter much but it’s still good practice

I think kotlin 1.9 or 2.0 is supposed to have an alternate method that doesn’t create the new array for values() each time

[Artem Kobzar]

Yes, it's entries static property

[ephemient]

in practice a linear search over a cached array is probably faster than a HashMap for 3 elements

[ephemient]

you'll have to benchmark for yourself to see where the crossover point is, if you care about that…

[Colton Idle]

Alright. my names actually do line up (or more so... im fine with changing my enum names to lineup) so maybe I'll see if I can get away with this

try {
    RollerToaster.Type.valueOf(this.input.type.toUppercase())
} catch (e: IllegalArgumentException) {
    Type.UNKNOWN
}

[Colton Idle]

although detekt doesn't like that for some reason. hrm

Detekt - SwallowedException: The caught exception is swallowed. The original exception could be lost.

[ephemient]

https://github.com/Kotlin/KEEP/blob/master/proposals/enum-entries.md

All further potential extensions, such as valueOfOrNull(String), hasValue(String) can be implemented on the standard library level as members or extensions over EnumEntries.

should get better in the future

[Colton Idle]

learned something new. thanks all.

if it helps. im just trying to deserialize a string from my backend to an enum of known types.
I think I'm just going to go the valueOf route and stick to the names from my backend instead of trying to rename them.

[Matteo Mirk]

You could shorten your try/catch above, and perhaps shut up Detekt, with this:

runCatching {
  RollerToaster.Type.valueOf(...)
}.getOrElse(Type.UNKNOWN)

[ephemient]

runCatching is the wrong solution. if there's a ExceptionInInitializerError (for example) that should be propagated

[Matteo Mirk]

But what If I don't want to propagate the exception and just swallow it in favour of a default value? Isn't it acceptable in that case?

[ephemient]

if you get an ExceptionInInitializerError, your whole enum class is broken and none of its values will work. there is zero reason to swallow it and allow execution to continue.

[ephemient]

the use cases for runCatching are meant to allow you to capture exceptions for later handling, not to drop them. https://github.com/Kotlin/KEEP/blob/master/proposals/stdlib/result.md#use-cases