Kotlin - Enum Class Example

The most basic usage of enum classes is implementing type-safe enums:

enum class Direction {
    NORTH, SOUTH, WEST, EAST
}

Each enum constant is an object. Enum constants are separated with commas.

Initialization

Since each enum is an instance of the enum class, they can be initialized as:

enum class Color(val rgb: Int) {
        RED(0xFF0000),
        GREEN(0x00FF00),
        BLUE(0x0000FF)
}

Enum Constants as Anonymous Classes

Enum constants can also declare their own anonymous classes:

package net.javaguides.kotlin.examples


enum class CardType {
    SILVER {
        override fun calculateCashbackPercent() = 0.25 f
    },
    GOLD {
        override fun calculateCashbackPercent() = 0.5 f
    },
    PLATINUM {
        override fun calculateCashbackPercent() = 0.75 f
    };

    abstract fun calculateCashbackPercent(): Float
}

fun main(args: Array < String > ) {
    val cashbackPercent = CardType.SILVER.calculateCashbackPercent();
    println(cashbackPercent);
}

Output:

0.25

Enums Implementing Interfaces

package net.javaguides.kotlin.examples

interface ICardLimit {
    fun getCreditLimit(): Int
}

enum class CardType: ICardLimit {
    SILVER {
        override fun getCreditLimit() = 100000
    },
    GOLD {
        override fun getCreditLimit() = 200000
    },
    PLATINUM {
        override fun getCreditLimit() = 300000
    }
}

fun main(args: Array < String > ) {
    val creditLimit = CardType.PLATINUM.getCreditLimit()
    println(creditLimit);
}

Output:

300000