1.简单用法

fun main(args: Array<String>) {
    println(Week.Monday)
    Week.values().forEach {
        println(it)
    }
    todo(Week.Wednesday)
}

fun todo(week: Week) {
    when (week) {
        in Week.Monday..Week.Friday -> println("上班")
        else -> println("休息")
    }
}

enum class Week {
    Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
}

运行结果如下:

2.高级用法

fun main(args: Array<String>) {
    println(Color.READ.r)
}

//枚举三元色
//红 r 255 g 0 b 0
//绿r 0 g 255 b 0
//蓝 r 0 g 0 b 255
enum class Color(val r: Int, val g: Int, val b: Int) {
    READ(255, 0, 0), GREEN(0, 255, 0), BLUE(0, 0, 255)
}

• 枚举也可以定义构造函数