Kotlin Kotlin Collections and Generics 3

Question 1

What does the `reified` keyword enable for type parameters in Kotlin?

Accepted Answer

Allows accessing the actual type at runtime inside an inline function

Answer

`reified` with `inline` functions preserves type information at runtime, allowing operations like `is T` and `T::class` inside the function.

Question 2

What does `sortedBy` do in Kotlin collections?

Accepted Answer

Returns a new sorted list ordered by the result of a selector function

Answer

`sortedBy` returns a new list sorted in natural ascending order of the key returned by the selector, without modifying the original.

Question 3

What does `zip` do in Kotlin?

Accepted Answer

Combines two collections element-by-element into a list of Pairs

Answer

`zip` pairs up elements from two collections by index, returning a list of `Pair` objects up to the length of the shorter collection.

Question 4

What is the `Set` interface in Kotlin?

Accepted Answer

An unordered collection that does not allow duplicate elements

Answer

`Set` is a collection that holds unique elements; it has no defined order in the base interface and does not allow duplicates.

Question 5

Which function creates a Map in Kotlin from a list of pairs?

Accepted Answer

both a and b are correct

Answer

Both `mapOf(key to value, ...)` and `list.toMap()` create maps; `mapOf()` takes pairs directly, `toMap()` is an extension on a collection of pairs.

Kotlin Practice Test