Kotlin by Example: When
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Kotlin has |
fun main() {
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When can be used in a way similar to a |
val x = 2
when (x) {
1 -> println("x == 1")
2 -> println("x == 2")
else -> println("x is neither 1 nor 2")
}
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However, like |
val result = when (x) {
1 -> "one"
2 -> "two"
else -> "unknown"
}
println("result = $result")
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Multiple matches can be used for a single branch. |
when (x) {
0, 1 -> println("x is 0 or 1")
else -> println("x is not 0 or 1")
}
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It is also possible to omit the argument to |
when {
x % 2 == 0 -> println("x is even")
x % 2 != 0 -> println("x is odd")
}
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A |
val y = 5
when (y) {
in 1..10 -> println("y is in the range 1..10")
!in 10..20 -> println("y is outside 10..20")
else -> println("y is something else")
}
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Type checking with |
fun describe(obj: Any): String =
when (obj) {
is String -> "String of length ${obj.length}"
is Int -> "Integer"
else -> "Unknown type"
}
println(describe("hello"))
println(describe(42))
}
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$ kotlinc main.kt -include-runtime -d main.jar
$ java -jar Main.jar
x == 2
result = two
x is not 0 or 1
x is even
y is in the range 1..10
String of length 5
Integer
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