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Mastering Kotlin Essentials

The when Statement

Explore how the when statement in Kotlin simplifies writing conditional logic by replacing if-else chains. Learn its syntax, use as an expression, and handling of multiple conditions to write clean, type-safe code.

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The when statement is an alternative to if-else-if. In every branch, we specify a predicate and the body that should be executed if this predicate returns true (and previous predicates did not). So, it works just like if-else-if but should be preferred because its syntax is better suited for multiple conditions.

Kotlin 1.5
fun main() {
    println("Is it going to rain?")
    val probability = 70
    when {
        probability < 40 -> {
            println("Na-ha")
        }
        probability <= 80 -> {
            println("Likely")
        }
        probability < 100 -> {
            println("Yes")
        }
        else -> {
            println("Holly Crab")
        }
    }
}

Like in an if statement, braces are needed only for bodies with more ...