Enum entries iteration in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an enum in Kotlin?

An enum in Kotlin is a special class that represents a group of constants. Each constant is called an enum entry.

beginner

How do you get all entries of an enum in Kotlin?

You use the values() function, which returns an array of all enum entries.

beginner

Write a Kotlin code snippet to print all entries of an enum named Color.

enum class Color { RED, GREEN, BLUE }

fun main() {
    for (color in Color.values()) {
        println(color)
    }
}

beginner

Can you use a for loop to iterate over enum entries in Kotlin?

Yes, you can use a for loop with EnumClass.values() to go through each enum entry one by one.

intermediate

What type does values() return when called on an enum class?

It returns an array of the enum type, for example, Array<Color> if called on Color enum.

Which function returns all entries of an enum in Kotlin?

A all()

B entries()

C values()

D list()

The values() function returns an array of all enum entries.

How do you iterate over enum entries in Kotlin?

A Using a for loop with <code>EnumClass.values()</code>

B Using <code>EnumClass.entries()</code>

C Using a while loop with <code>EnumClass.all()</code>

D Using <code>EnumClass.list()</code>

You use a for loop with EnumClass.values() to iterate over enum entries.

What type does EnumClass.values() return?

A Array of enum entries

B List of enum entries

C Set of enum entries

D Map of enum entries

values() returns an array of enum entries.

Can you modify the array returned by values() to add new enum entries?

A Yes, you can add new entries anytime

B No, enum entries are fixed at compile time

C Yes, but only inside the enum class

D Only if you use a mutable list

Enum entries are fixed at compile time and cannot be changed at runtime.

What will this code print?

enum class Day { MON, TUE, WED }
fun main() {
  for (d in Day.values()) println(d)
}

A 0 1 2

B Error

C Day.MON Day.TUE Day.WED

D MON TUE WED

The code prints each enum entry name on its own line: MON, TUE, WED.

Explain how to iterate over all entries of an enum in Kotlin and why this is useful.

Think about how you can get all enum constants and loop through them.

Describe what the values() function returns when called on an enum class and how you can use it.

Consider the type and purpose of the <code>values()</code> function.