Combining flows (zip, combine) in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to zip two flows and collect their combined values.

Kotlin

val flow1 = flowOf(1, 2, 3)
val flow2 = flowOf("A", "B", "C")

flow1.[1](flow2) { a, b -> "$a$b" }
    .collect { println(it) }

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

Azip

Bcombine

Cmap

DflatMapConcat

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'combine' instead of 'zip' which merges latest values instead of pairing.

Using 'map' which transforms elements of a single flow.

The zip function combines two flows by pairing their elements one by one.

2fill in blank

medium

Complete the code to combine two flows and collect their latest values.

Kotlin

val flow1 = flowOf(1, 2, 3)
val flow2 = flowOf("X", "Y", "Z")

flow1.[1](flow2) { a, b -> "$a$b" }
    .collect { println(it) }

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

Azip

Bcombine

Cmap

DflatMapLatest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'zip' which pairs elements one by one instead of combining latest values.

Using 'map' which only transforms a single flow.

The combine function merges two flows by combining their latest emitted values.

3fill in blank

hard

Fix the error in the code to correctly zip two flows and print combined results.

Kotlin

val numbers = flowOf(1, 2, 3)
val letters = flowOf("a", "b", "c")

numbers.[1](letters) { num, letter -> "$num$letter" }
    .collect { println(it) }

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

Azip

Bcombine

Cmap

DflatMapConcat

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'combine' which merges latest values instead of pairing.

Using 'map' which only works on a single flow.

Using zip pairs elements from both flows correctly for combined output.

4fill in blank

hard

Fill both blanks to create a dictionary of word lengths for words longer than 3 characters.

Kotlin

val words = listOf("apple", "bat", "carrot", "dog")

val lengths = words.associateWith { [1] }
    .filter { it.value [2] 3 }

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

Ait.length

Bit.size

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'it.size' which is not a property of String.

Using '<' instead of '>' causing wrong filtering.

it.length gets the length of each word, and > filters words longer than 3.

5fill in blank

hard

Fill all three blanks to create a map of uppercase words to their lengths for words longer than 4 characters.

Kotlin

val words = listOf("pear", "plum", "banana", "kiwi")

val result = words.filter { it.length [1] 4 }
    .associateBy(
        keySelector = { it.[2]() },
        valueTransform = { it.[3] }
    )

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

A>

Blength

Cuppercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in filter.

Using 'uppercase' property instead of function call.

Using 'size' instead of 'length' for string length.

Filter words longer than 4, use uppercase() for keys, and length for values.