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galcyurio
galcyurio

Reputation: 1855

Difference between Enum.values() and enumValues() in kotlin

In the official document, I found enumValues() function.

I used enumValues() function, but I cannot find difference.

enum class RGB {
    RED, GREEN, BLUE
}

RGB.values().joinToString { it.name } // RED, GREEN, BLUE
enumValues<RGB>().joinToString { it.name } // RED, GREEN, BLUE

What difference between enumValues() and Enum.values()?

Is it a function for platforms other than JVM? Or are there other use cases?

Upvotes: 9

Views: 3605

Answers (1)

zsmb13
zsmb13

Reputation: 89578

The problem with values() is that it only exists on each concrete enum class, and you can't call it on a generic enum to get its values, which is quite useful in some cases. Taking just the simplest example of wanting to access all values in a String, enumValues lets you write a function like this:

inline fun <reified T: Enum<T>> getEnumValuesString(): String {
    // could call RGB.values(), but not T.values()
    // even with the generic constraint and reified generics

    // this works, however
    return enumValues<T>().joinToString()
}

Which can then be called with any enum class you've defined:

getEnumValuesString<RGB>()

Upvotes: 17

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