Map transformation in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new map with values doubled.

Kotlin

val numbers = mapOf("a" to 1, "b" to 2, "c" to 3)
val doubled = numbers.mapValues { it.value [1] 2 }
println(doubled)

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' adds 2 instead of doubling.

Using '-' or '/' changes values incorrectly.

We use * to multiply each value by 2 to double it.

2fill in blank

medium

Complete the code to filter map entries with values greater than 2.

Kotlin

val numbers = mapOf("a" to 1, "b" to 3, "c" to 4)
val filtered = numbers.filter { it.value [1] 2 }
println(filtered)

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

A<

B<=

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' filters smaller values.

Using '==' filters only values equal to 2.

We use '>' to keep entries with values greater than 2.

3fill in blank

hard

Fix the error in the code to convert map keys to uppercase.

Kotlin

val original = mapOf("one" to 1, "two" to 2)
val upperKeys = original.mapKeys { it.key.[1]() }
println(upperKeys)

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

AtoLowerCase

Buppercase

CtoUpperCase

Dcapitalize

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'toUpperCase()' is deprecated in modern Kotlin.

Using 'toLowerCase()' changes to lowercase, not uppercase.

In Kotlin 1.5+, 'uppercase()' is the correct function to convert strings to uppercase.

4fill in blank

hard

Fill both blanks to create a map of word lengths for words longer than 3 letters.

Kotlin

val words = listOf("cat", "house", "tree", "a")
val lengths = words.filter { it.length [1] 3 }.associateWith { it.[2] }
println(lengths)

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

A>

Blength

C<

Dfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' filters shorter words.

Using 'first' returns first character, not length.

We filter words with length > 3 and map each word to its length.

5fill in blank

hard

Fill all three blanks to create a map with uppercase keys and values doubled for values > 1.

Kotlin

val data = mapOf("x" to 1, "y" to 2, "z" to 3)
val result = data.filter { it.value [1] 1 }.mapKeys { it.key.[2]() }.mapValues { it.value [3] 2 }
println(result)

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

A<

B>

C*

Duppercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' filters smaller values.

Using 'toUpperCase()' instead of 'uppercase()' in modern Kotlin.

We filter values > 1, convert keys to uppercase, and double the values.