Collections (List, Map, Set) in Android Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a List in Kotlin collections?

A List is an ordered collection of elements that can contain duplicates. You can access elements by their index.

beginner

How does a Set differ from a List in Kotlin?

A Set is a collection that holds unique elements only. It does not maintain insertion order and does not allow duplicates.

beginner

What is a Map in Kotlin collections?

A Map stores key-value pairs. Each key is unique and maps to exactly one value.

beginner

How do you create an immutable List in Kotlin?

Use listOf() function. For example: val myList = listOf("apple", "banana") creates a read-only list.

intermediate

What function creates a mutable Map in Kotlin?

Use mutableMapOf(). For example: val myMap = mutableMapOf("key1" to 1, "key2" to 2) creates a map you can change.

Which Kotlin collection type allows duplicate elements and maintains order?

A List

B Set

C Map

D None of the above

A List allows duplicates and keeps the order of elements.

What happens if you add a duplicate element to a Kotlin Set?

A It adds the duplicate

B It ignores the duplicate

C It throws an error

D It replaces the existing element

Sets ignore duplicates and keep only unique elements.

How do you access a value in a Kotlin Map?

A By index

B By value

C By key

D By position

You access values in a Map using their unique keys.

Which function creates a mutable List in Kotlin?

A listOf()

B mapOf()

C setOf()

D mutableListOf()

mutableListOf() creates a list you can change.

What is the key characteristic of a Kotlin Map?

A It stores key-value pairs with unique keys

B It stores only unique values

C It stores ordered elements

D It stores only numbers

A Map stores pairs where each key is unique and maps to a value.

Explain the differences between List, Set, and Map in Kotlin collections.

Think about how each collection stores and accesses data.

Describe how to create and use a mutable List and a mutable Map in Kotlin.

Focus on the functions and what mutability means.