Kotlin Kotlin Collections 2

Question 1

What does `groupBy` return in Kotlin?

Accepted Answer

A Map where keys are the grouping criteria and values are lists of elements

Answer

A List of pairs

Answer

A Set of keys

Answer

A sorted list

Question 2

Which function finds the first element matching a predicate in Kotlin?

Accepted Answer

firstOrNull

Answer

findFirst

Answer

first

Answer

filter

Question 3

How do you sort a list in descending order in Kotlin?

Accepted Answer

list.sortedDescending()

Answer

list.sort()

Answer

list.reversed()

Answer

list.sortByDescending()

Question 4

What does the `any` function do on a Kotlin collection?

Accepted Answer

Returns true if at least one element satisfies the predicate

Answer

Returns the first element

Answer

Returns all elements matching the predicate

Answer

Returns the count of matching elements

Question 5

What is a Sequence in Kotlin and how does it differ from a List?

Accepted Answer

Sequences are lazy; operations are applied one element at a time instead of creating intermediate lists

Answer

Sequences are sorted lists

Answer

Sequences are thread-safe collections

Answer

Sequences store unique elements only

Question 6

Which function removes duplicate elements from a Kotlin list?

Accepted Answer

distinct()

Answer

unique()

Answer

toSet()

Answer

deduplicate()