Lazy evaluation vs eager evaluation in Kotlin - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a lazy value in Kotlin.

Kotlin

val lazyValue: String by [1] {
    println("Computed!")
    "Hello"
}

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

Aeager

Bvar

Cval

Dlazy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'val' or 'var' instead of 'lazy' for lazy initialization.

Trying to use 'eager' which is not a Kotlin keyword.

In Kotlin, lazy is used to create a lazily evaluated property.

2fill in blank

medium

Complete the code to create an eager list in Kotlin.

Kotlin

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

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AtoList

Bmap

Cfilter

DasSequence

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'asSequence' which creates a lazy sequence, not an eager list.

Using 'map' or 'filter' without collecting results eagerly.

toList() creates a new list eagerly from the original collection.

3fill in blank

hard

Fix the error in the code to make the sequence evaluated lazily.

Kotlin

val seq = listOf(1, 2, 3).[1]().map { it * 2 }

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

AasSequence

BtoList

Cmap

Dfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'toList' which evaluates eagerly.

Applying 'map' directly on list which is eager.

asSequence() converts the list to a lazy sequence, delaying computation.

4fill in blank

hard

Fill both blanks to create a lazy sequence and then convert it back to a list eagerly.

Kotlin

val result = listOf(1, 2, 3).[1]().map { it + 1 }.[2]()

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

AasSequence

BtoList

Cfilter

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'map' or 'filter' in wrong places.

Not converting back to list after lazy operations.

First, asSequence() creates a lazy sequence, then toList() collects results eagerly.

5fill in blank

hard

Fill all three blanks to create a lazy property, access it, and print its value.

Kotlin

val lazyVal: String by [1] {
    println("Computing...")
    "Kotlin"
}

fun main() {
    println(lazyVal)
    println(lazyVal.[2])
    println(lazyVal.[3])
}

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

Alazy

BtoUpperCase()

Clength

Dsubstring(0, 3)

Attempts:

3 left

💡 Hint

Common Mistakes

Using eager initialization instead of lazy.

Mixing up string methods or forgetting parentheses.

The property is lazy initialized with lazy. Then we print its length and uppercase form.