Kotlin for C# Developers

4.3. Enums

Enums are classes in Kotlin and their values are named in SCREAMING_CASE.

C#

public enum TrafficLight
{
    Red,
    Yellow,
    Green
}

Kotlin

enum class TrafficLight {
    RED,
    YELLOW,
    GREEN
}

Since they are classes, they can have properties and methods.

Kotlin

enum class TrafficLight(private val sameColourAs: String) {
    RED("tomato"),
    YELLOW("banana"),
    GREEN("pea");

    fun describe() {
        println("I'm the same colour as a $sameColourAs")
    }
}

TrafficLight.YELLOW.describe() // "I'm the same colour as a banana"

(I told you we’d see a semicolon eventually! Did you spot it?)

And they can extend any type (not just integral types).

C#

public enum TrafficLight : byte
{
    Red,
    Yellow,
    Green
}

Kotlin

enum class TrafficLight : Describable, Serializable {
    RED,
    YELLOW,
    GREEN;

    override fun describe() {/*...*/}
    override fun serialize() {/*...*/}
}

TrafficLight.RED.describe()
TrafficLight.GREEN.serialize()

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