How to create enum value from string value and class without exact generic value?

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1

How can I convert this Java code (which is using raw classes) to Kotlin correctly?

public Enum getEnumValue(Class enumClass, String value) {
    return Enum.valueOf(enumClass, value);
}

When I try the following:

fun getEnumValue(enumClass: Class<Enum<*>>, value: String): Enum<*> =
        java.lang.Enum.valueOf(enumClass, value)

I get the warning

Type mismatch: inferred type is Enum<*>! but Enum<in Enum<*>!>! was expected

and with latest dev build the warning turns to compilation error…
Thanks.

2

I’m not able to replicate your warning or error, but maybe this code helps:

fun getEnumValue(enumClass: Class<Enum<*>>, value: String): Enum<*> =
    enumClass.enumConstants.first { it.name == value }
3

Thanks, that helps to get rid of the warning. I am still wondering if there is a way to call java.lang.Enum.valueOf(class, name) with Kotlin generics (instead of raw classes in java) with a class where the enum type in generic is not known.

4

Do you need this function to receive any possible Class or only classes that are verified at compile time to be enums? I ask because your original Java code could receive e.g. Class<String>, but your Kotlin equivalent does not.

If enum requirement is fine, then I believe the proper solution is like this:

fun <T : Enum<T>> getEnumValue(enumClass: Class<T>, value: String): T {
    return java.lang.Enum.valueOf(enumClass, value)
}

But I’m not sure if this helps you match, because if you are using Class<Enum<*>> currently, then you will probably have exactly the same problem executing this above function as you have problem executing Enum.valueOf() right now.

5

Hi, no, I need it to receive any possible Class as you wrote, I cannot do <T : Enum<T>> - on the input I only have value type as KClass<*> and a String value - depending on a class it’s trying to convert the String value to appropriate type, e.g. Double, BigDecimal, Enum, ZonedDateTime…