Closures and variable capture in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a lambda that adds 5 to its input.

Kotlin

val addFive = { x: Int -> x [1] 5 }

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' causes subtraction.

Using '*' or '/' changes the operation to multiplication or division.

The lambda adds 5 to the input using the + operator.

2fill in blank

medium

Complete the code to capture the variable 'factor' inside the lambda.

Kotlin

fun makeMultiplier(factor: Int): (Int) -> Int = { x -> x [1] factor }

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' adds instead of multiplies.

Using '-' or '/' changes the operation incorrectly.

The lambda multiplies the input by the captured 'factor' using '*'.

3fill in blank

hard

Fix the error in the lambda to correctly capture the variable 'count'.

Kotlin

var count = 0
val increment = { count [1] 1 }

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

A=

B-=

C+=

D*=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' alone does not increment the value.

Using '-=' or '*=' changes the value incorrectly.

Use '+=' to increment the variable 'count' inside the lambda.

4fill in blank

hard

Fill both blanks to create a lambda that filters a list by length greater than 3.

Kotlin

val words = listOf("cat", "house", "dog", "elephant")
val filtered = words.filter { word -> word.length [1] [2] }

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

A>

B3

C<

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' filters words shorter than 3.

Using 4 instead of 3 changes the filter condition.

The lambda filters words with length greater than 3 using '>' and 3.

5fill in blank

hard

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

Kotlin

val words = listOf("apple", "bat", "carrot", "dog")
val result = words.filter { [1] -> [1].length [2] 4 }
    .associateWith { [3].uppercase() }

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

Aword

B>

Cit

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'it' in filter parameter causes error.

Using '<' filters wrong words.

Using 'length' as variable name is incorrect.

The lambda filters words with length > 4 and maps each word to its uppercase version using 'word' and '>'.