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Control Flow

Control flow allows your program to make decisions and repeat actions. Kotlin provides conditional, looping, and branching statements similar to Java, but with a more concise and expressive syntax.

1. Conditional Statements​

if, else if, else

val number = 10
if (number > 0) {
    println("Positive")
} else if (number < 0) {
    println("Negative")
} else {
    println("Zero")
}

In Kotlin, if can also return a value:

val max = if (a > b) a else b

when – Kotlin's powerful switch

val day = 2
val name = when (day) {
    1 -> "Monday"
    2 -> "Tuesday"
    3 -> "Wednesday"
    else -> "Other"
}
println(name)

2. Looping Statements​

for loop

Iterate over a range or collection:

for (i in 1..5) {
    println(i)
}

val items = listOf("A", "B", "C")
for (item in items) {
    println(item)
}

while loop

var x = 5
while (x > 0) {
    println(x)
    x--
}

do-while loop

var y = 3
do {
    println(y)
    y--
} while (y > 0)

3. Branching Statements​

break exits the nearest loop:

for (i in 1..5) {
    if (i == 3) break
    println(i)
}

continue skips current iteration:

for (i in 1..5) {
    if (i == 3) continue
    println(i)
}

return exits from a function:

fun greet(name: String?) {
    if (name == null) return
    println("Hello, $name")
}

Labels with break, continue, and return​

Lable is Used for nested control flow. With label you can break or continue a specefic loop.

outer@ for (i in 1..3) {
    for (j in 1..3) {
        if (j == 2) continue@outer
        println("i=$i, j=$j")
    }
}