Functional Kotlin

when expression

Unlike other C-style languages, Kotlin doesn't have a switch statement, but a when expression that is a lot more flexible:

val x: Int = /*Some unknown value here*/when (x) {    0 -> println("x is zero")    1, 2 -> println("x is 1 or 2")    in 3..5 -> println("x is between 3 and 5")    else -> println("x is bigger than 5... or maybe is negative...")}

when are expressions:

val message = when {    2 > 1 -> "2 is greater than 1"    else -> "This never gonna happen"}println(message)

And they also can be used to replace if expression: