Accessing elements safely in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to safely access the first element of the list.

Kotlin

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

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

Afirst()

Bget(0)

CfirstOrNull()

DelementAt(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Using get(0) which throws an exception if the list is empty.

Using first() which throws an exception if the list is empty.

The firstOrNull() function returns the first element or null if the list is empty, preventing errors.

2fill in blank

medium

Complete the code to safely access the element at index 2.

Kotlin

val list = listOf("a", "b")
val element = list.[1](2)

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AgetOrElse

Bget

CelementAt

DelementAtOrNull

Attempts:

3 left

💡 Hint

Common Mistakes

Using get(2) which throws an exception if index is out of bounds.

Using elementAt(2) which throws an exception if index is invalid.

The elementAtOrNull() function returns the element at the given index or null if the index is out of bounds.

3fill in blank

hard

Fix the error in safely accessing the last element of the list.

Kotlin

val list = listOf<Int>()
val last = list.[1]()

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AlastOrNull

Blast

CgetLast

DelementAt

Attempts:

3 left

💡 Hint

Common Mistakes

Using last() which throws an exception if the list is empty.

Using elementAt() without checking index.

lastOrNull() safely returns the last element or null if the list is empty, avoiding exceptions.

4fill in blank

hard

Fill both blanks to create a map of words to their lengths, but only for words longer than 3 characters.

Kotlin

val words = listOf("cat", "elephant", "dog", "lion")
val lengths = words.associateWith { [1] }
val filtered = lengths.filter { it.value [2] 3 }

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Ait.length

B>

C<

Dit.size

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > in the filter condition.

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

it.length gets the length of each word, and filtering with > 3 keeps only words longer than 3 characters.

5fill in blank

hard

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

Kotlin

val words = listOf("apple", "bat", "carrot", "dog")
val result = words.associate { word -> [1] to [2] }
val filtered = result.filter { it.value [3] 4 }

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Aword.uppercase()

Bword.length

C>

Dword.toUpperCase()

Attempts:

3 left

💡 Hint

Common Mistakes

Using deprecated toUpperCase() instead of uppercase().

Using < instead of > in the filter condition.

word.uppercase() converts words to uppercase, word.length gets their length, and filtering with > 4 keeps words longer than 4 characters.