When with multiple conditions in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of when with multiple conditions combined by commas

What is the output of this Kotlin code snippet?

Kotlin

fun main() {
    val x = 3
    val result = when (x) {
        1, 2 -> "One or Two"
        3, 4 -> "Three or Four"
        else -> "Other"
    }
    println(result)
}

A Three or Four

B Compilation error

C One or Two

D Other

💡 Hint

Remember that commas separate multiple matching values in a when branch.

The variable x is 3, and the when expression checks if x matches any of the values in each branch. The branch 3, 4 -> "Three or Four" matches because x is 3, so it returns "Three or Four".

❓ Predict Output

intermediate

When with condition ranges and multiple conditions

What will this Kotlin program print?

Kotlin

fun main() {
    val score = 85
    val grade = when (score) {
        in 90..100 -> "A"
        in 80..89, 75 -> "B"
        else -> "C"
    }
    println(grade)
}

A Runtime exception

B B

C C

D A

💡 Hint

Check if the score matches any of the conditions including the single value 75.

The score is 85, which falls in the range 80..89, so the branch in 80..89, 75 -> "B" matches and returns "B".

🔧 Debug

advanced

Identify the error in when with multiple conditions

What error does this Kotlin code produce?

Kotlin

fun main() {
    val y = 5
    val output = when (y) {
        1, 2 -> "Low"
        3, 4 -> "Medium"
        else -> "High"
    }
    println(output)
}

A No error, prints "Medium"

B TypeError: Cannot compare Int with Int

C SyntaxError: Missing comma between 3 and 4

D RuntimeException: Unreachable code

💡 Hint

Look carefully at the syntax between 3 and 4 in the when expression.

The branch 3 4 -> "Medium" is missing a comma between 3 and 4, which causes a syntax error in Kotlin.

❓ Predict Output

advanced

When with multiple conditions and else branch

What is the output of this Kotlin code?

Kotlin

fun main() {
    val input = "apple"
    val category = when (input) {
        "banana", "orange" -> "Citrus"
        "apple", "pear" -> "Pome"
        else -> "Unknown"
    }
    println(category)
}

A Pome

B Unknown

C Citrus

D Compilation error

💡 Hint

Check which branch matches the input string.

The input is "apple", which matches the branch "apple", "pear" -> "Pome", so the output is "Pome".

🧠 Conceptual

expert

How does Kotlin's when handle multiple conditions?

Which statement best describes how Kotlin's when expression handles multiple conditions separated by commas in a single branch?

A All conditions separated by commas must be true simultaneously for the branch to match.

B Multiple conditions separated by commas cause a compilation error.

C The branch matches only if the subject matches the first condition and ignores the rest.

D The branch matches if the subject equals any one of the listed conditions separated by commas.

💡 Hint

Think about how commas work in a when branch.

In Kotlin, when you separate multiple conditions by commas in a single branch, it means the branch matches if the subject equals any one of those conditions.