Also function behavior and use cases in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use the also function to print the number before returning it.

Kotlin

fun printNumber(num: Int): Int {
    return num.[1] {
        println("Number is: $it")
    }
}

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

Aapply

Brun

Calso

Dlet

Attempts:

3 left

💡 Hint

Common Mistakes

Using apply which returns the object but uses this instead of it.

Using let which returns the lambda result, not the original object.

The also function lets you perform an action with the object (here, num) and then returns the original object. This is perfect for printing and returning the same value.

2fill in blank

medium

Complete the code to add an element to the list and print the updated list using also.

Kotlin

val numbers = mutableListOf(1, 2, 3)
numbers.[1](4).also {
    println("Updated list: $numbers")
}

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

Aalso

Brun

Clet

Dapply

Attempts:

3 left

💡 Hint

Common Mistakes

Using apply which expects this and is used for configuring objects.

Using let which returns the lambda result, not the original object.

also is used here to perform an action (printing) after adding an element, while returning the original result of add.

3fill in blank

hard

Fix the error in the code by choosing the correct function to chain calls and print the object.

Kotlin

val text = "Hello"
val result = text.[1] {
    println(it)
}.uppercase()

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

Aapply

Balso

Crun

Dwith

Attempts:

3 left

💡 Hint

Common Mistakes

Using run which returns the lambda result, breaking the chain.

Using apply which uses this and may confuse chaining.

also returns the original object, so uppercase() can be called on the string. apply returns the object but uses this, run returns the lambda result, and with is not called as an extension.

4fill in blank

hard

Fill both blanks to create a mutable list, add an element, and print the list using also.

Kotlin

val list = mutableListOf(1, 2, 3).[1] {
    this.add(4)
}.[2] {
    println(it)
}

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

Aalso

Blet

Capply

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Using let which returns the lambda result, not the object.

Using run which returns the lambda result.

apply is used to add an element because it uses this and returns the object. Then also is used to print the list and return it.

5fill in blank

hard

Fill all three blanks to create a string, print it, convert to uppercase, and print again using also.

Kotlin

val message = "hello".[1] {
    println("Original: $it")
}.[2]().[3] {
    println("Uppercase: $it")
}

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

Aalso

Blet

Cuppercase

Dapply

Attempts:

3 left

💡 Hint

Common Mistakes

Using let which changes the return value and breaks chaining.

Using apply which uses this and is less clear here.

also is used to print the original string, then uppercase() converts it, and also prints the uppercase string. This keeps the original object flowing through the chain.