Summary - Conditionals

Combine if, if expression and when to write a day-of-week app.

Summary - Conditionals

In this summary you'll combine if, the if expression and when to build a day-of-week app. In previous lessons you learned:

condition checks with if
alternative branches with else and else if
returning values with the if expression
multi-way selection with when

We'll do two mini tasks: convert a day number to a name (when expression) and categorize a temperature (if expression).

Exercise Find the day name with when

Write a fun main(). Assign 3 to val day. Write val name = when (day) { 1 -> "Monday" 2 -> "Tuesday" 3 -> "Wednesday" 4 -> "Thursday" 5 -> "Friday" else -> "Weekend" }. Print the result with println(name).

Show example solution

fun main() {
    val day = 3
    val name = when (day) {
        1 -> "Monday"
        2 -> "Tuesday"
        3 -> "Wednesday"
        4 -> "Thursday"
        5 -> "Friday"
        else -> "Weekend"
    }
    println(name)
}

Exercise Categorize the temperature

Write a fun main(). Assign 25 to val temp. Write val category = if (temp >= 30) "Hot" else if (temp >= 15) "Mild" else "Cold". Print the result with println(category).

Show example solution

fun main() {
    val temp = 25
    val category = if (temp >= 30) "Hot" else if (temp >= 15) "Mild" else "Cold"
    println(category)
}

Test yourself

Which is the most readable construct to compare a value against 5 options?
- if/else if chain
- Nested if
- Ternary operator
- when expression
Show answer

when expression — when is the most readable for multi-way selection.

Complete the if expression

val category = if (temp >= 30) "Hot" ____ "Normal"

Show answer

val category = if (temp >= 30) "Hot" else "Normal"

Next lesson: The for loop

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies