Map creation (mapOf, mutableMapOf) in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does mapOf create in Kotlin?

mapOf creates an immutable map, meaning you cannot add or remove entries after creation.

beginner

What is the difference between mapOf and mutableMapOf?

mapOf creates an immutable map, while mutableMapOf creates a mutable map that allows adding, removing, or changing entries.

beginner

How do you create a map with keys "apple" and "banana" and values 1 and 2 using mapOf?

Use val fruitMap = mapOf("apple" to 1, "banana" to 2).

beginner

How can you add a new entry to a map created with mutableMapOf?

Use the assignment syntax: mutableMap["key"] = value to add or update entries.

beginner

What happens if you try to add an entry to a map created with mapOf?

You will get a compile-time error because the map is immutable and does not support adding entries.

Which Kotlin function creates a map that you cannot change after creation?

A mapOf

B mutableMapOf

C hashMapOf

D arrayMapOf

mapOf creates an immutable map that cannot be changed after creation.

How do you add a new key-value pair to a mutable map in Kotlin?

A mutableMap.add("key", value)

B mutableMap.put("key", value)

C mutableMap["key"] = value

D mutableMap.insert("key", value)

You add or update entries in a mutable map using the bracket syntax: mutableMap["key"] = value.

What type of map does mutableMapOf create?

A Immutable map

B Mutable map

C Sorted map

D Linked map

mutableMapOf creates a mutable map that can be changed after creation.

Which of these is a correct way to create a map with keys "x" and "y" and values 10 and 20?

A mutableMapOf("x" -> 10, "y" -> 20)

B mapOf("x", 10, "y", 20)

C mutableMapOf("x" = 10, "y" = 20)

D mapOf("x" to 10, "y" to 20)

Use the to keyword to pair keys and values: mapOf("x" to 10, "y" to 20).

What will happen if you try to do map["newKey"] = 5 on a map created with mapOf?

A It will cause a compile-time error

B It will add the new key-value pair

C It will update the existing key

D It will silently fail

Maps created with mapOf are immutable, so trying to add or update entries causes a compile-time error.

Explain the difference between mapOf and mutableMapOf in Kotlin.

Think about whether you can change the map after creating it.

How do you create a mutable map and add a new key-value pair to it?

Remember the syntax for adding entries to a mutable map.