Set creation (setOf, mutableSetOf) in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does setOf() do in Kotlin?

setOf() creates an immutable set, which means you cannot add or remove elements after creation.

beginner

How is mutableSetOf() different from setOf()?

mutableSetOf() creates a mutable set, allowing you to add or remove elements after the set is created.

beginner

What happens if you try to add an element to a set created with setOf()?

You will get a compilation error because the set is immutable and does not support modification.

beginner

Show how to create a mutable set of strings with elements "apple", "banana", and "cherry".

val fruits = mutableSetOf("apple", "banana", "cherry")

intermediate

Why might you choose a set over a list in Kotlin?

Because sets automatically prevent duplicate elements and provide faster checks for whether an element exists.

Which Kotlin function creates an immutable set?

A listOf()

B mutableSetOf()

C setOf()

D arrayOf()

setOf() creates an immutable set, while mutableSetOf() creates a mutable set.

What will happen if you call add() on a set created with setOf()?

A It throws a runtime exception.

B It causes a compilation error.

C It adds the element successfully.

D It removes the element instead.

Since setOf() returns an immutable set, calling add() is not allowed and causes a compilation error.

How do you create an empty mutable set of integers in Kotlin?

A mutableSetOf<Int>()

B setOf<Int>()

C emptySet<Int>()

D listOf<Int>()

mutableSetOf() creates an empty mutable set of integers.

Which of these is true about sets in Kotlin?

A Sets are always mutable.

B Sets maintain the order of elements.

C Sets allow duplicate elements.

D Sets do not allow duplicate elements.

Sets do not allow duplicate elements. They may or may not maintain order depending on implementation.

What is the type of the variable declared as val s = setOf(1, 2, 3)?

A Set<Int>

B Array<Int>

C List<Int>

D MutableSet<Int>

setOf() returns an immutable Set of the given type.

Explain how to create and use both immutable and mutable sets in Kotlin.

Think about whether you want to change the set after you create it.

Describe a real-life example where using a set is better than a list.

Think about a collection where you never want repeated items.