Must if as an expression always have an else?

Yes. When you use if as an expression (to return a value), else is required. Without else the compiler cannot determine a value for all branches.

Can I use if without curly braces in Kotlin?

Yes, for a single statement: if (x > 0) println("positive"). For readability and fewer bugs, KotlinGuide recommends always using braces for multi-line or nested logic.

Beginner 7 min readKotlin 2.0

Kotlin If / Else — Conditions and Expressions

Kotlin if/else works like other languages but with one bonus: it can be used as an expression to return a value.

What You Will Learn

Basic if/else syntax
else if for multiple conditions
if as an expression (replaces ternary)
Nested if statements

Basic if / else

Use if to check a condition. The block runs when the condition is true.

Basic if/else

kotlin
fun main() {
    val score = 75
    if (score >= 90) {
        println("Excellent")
    } else if (score >= 60) {
        println("Good")
    } else {
        println("Keep practicing")
    }
}

Output

Good

75 is >= 60 but not >= 90, so the second branch executes.

Beginner Tip: Always cover the else case to handle unexpected values.

if as an Expression

Kotlin if can return a value — no ternary operator needed.

if Expression

kotlin
fun main() {
    val age = 20
    val status = if (age >= 18) "Adult" else "Minor"
    println(status)

    val max = if (10 > 7) 10 else 7
    println(max)
}

Output

Adult 10

When used as an expression, if/else must have an else branch. The last expression in each branch is the returned value.

Best Practice: Use if as an expression instead of a ternary operator. It is more readable and Kotlin has no ternary ?:.

Nested if

You can nest if statements inside each other.

Nested if

kotlin
fun main() {
    val x = 10
    if (x > 0) {
        if (x % 2 == 0) {
            println("Positive even")
        } else {
            println("Positive odd")
        }
    }
}

Output

Positive even

The outer if checks if x is positive. The inner if checks if it is even.

Practice Exercise

Exercisepredict output

What prints? val n = 5 val result = if (n % 2 == 0) "Even" else "Odd" println(result)

Quick Quiz

Kotlin has a ternary operator like condition ? a : b.

Kotlin If / Else — Conditions and Expressions

What You Will Learn

Basic if / else

Basic if/else

if as an Expression

if Expression

Nested if

Nested if

Practice Exercise

Quick Quiz

Frequently Asked Questions

Related Tutorials