Java streams vs Kotlin sequences - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Kotlin sequence from a list.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val seq = numbers.[1]()

Drag options to blanks, or click blank then click option'

AtoSequence

Bstream

CasSequence

DsequenceOf

Attempts:

3 left

💡 Hint

Common Mistakes

Using Java's stream() method which is not available on Kotlin lists.

Trying to use toSequence() which does not exist.

Use asSequence() to convert a list to a Kotlin sequence.

2fill in blank

medium

Complete the code to filter even numbers using a Kotlin sequence.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val evens = numbers.asSequence().[1] { it % 2 == 0 }.toList()

Drag options to blanks, or click blank then click option'

AflatMap

Bmap

Creduce

Dfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using map which transforms elements but does not filter.

Using reduce which combines elements into one value.

The filter function selects elements matching the condition.

3fill in blank

hard

Fix the error in the code to convert a Kotlin sequence back to a list.

Kotlin

val seq = listOf(1, 2, 3).asSequence()
val list = seq.[1]()

Drag options to blanks, or click blank then click option'

AasList

BtoList

CtoSequence

DtoArray

Attempts:

3 left

💡 Hint

Common Mistakes

Using toSequence() which does not convert back to list.

Using asList() which is not a Kotlin function.

Use toList() to convert a sequence back to a list.

4fill in blank

hard

Fill both blanks to create a Java stream from a list and collect it back to a list.

Kotlin

val list = listOf(1, 2, 3, 4)
val stream = list.[1]()
val result = stream.collect(Collectors.[2]())

Drag options to blanks, or click blank then click option'

Astream

BtoList

DtoSet

Attempts:

3 left

💡 Hint

Common Mistakes

Using Kotlin sequence methods instead of Java stream methods.

Using toSet collector instead of toList.

Use stream() to get a Java stream and Collectors.toList() to collect it back to a list.

5fill in blank

hard

Fill all three blanks to create a Kotlin sequence, filter odd numbers, and convert to a list.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val result = numbers.[1]().[2] { it % 2 != 0 }.[3]()

Drag options to blanks, or click blank then click option'

AasSequence

Bfilter

CtoList

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using map instead of filter for selecting odd numbers.

Forgetting to convert the sequence back to a list.

First convert to a sequence with asSequence(), then filter odd numbers with filter, and finally convert back to a list with toList().