The if { ... } else { ... } expression

In Kotlin, the if control flow element can be used in the same way as it is used in Java. The following example demonstrates the use of if as a usual statement:

fun ifStatement() {
    val a = 4
    if (a < 5) {
        println(a)
    }
}

If you are using the if { ... } else { ... } control flow element as an expression, you have to declare the else block, as follows:

fun ifExpression() {
    val a = 5
    val b = 4
    val max = if (a > b) a else b
}

The preceding example shows that if { ... } else { ... } returns a value.