Extension function syntax in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define an extension function named greet for the String class that returns a greeting message.

Kotlin

fun String.[1](): String {
    return "Hello, $this!"
}

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

Agreet

Bhello

CsayHello

Dwelcome

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put the function name after the receiver type.

Using a function name that is not descriptive.

The extension function name is greet, so the correct syntax is fun String.greet().

2fill in blank

medium

Complete the code to call the extension function greet on the string "World".

Kotlin

val message = "World".[1]()
println(message)

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AsayHello

Bhello

Cwelcome

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a function name that was not defined as an extension.

Forgetting the parentheses when calling the function.

To call the extension function defined as greet, use "World".greet().

3fill in blank

hard

Fix the error in the extension function definition by completing the blank with the correct receiver type.

Kotlin

fun [1].greet(): String {
    return "Hi, $this!"
}

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AInt

BDouble

CString

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong receiver type like Int or Double.

Omitting the receiver type entirely.

The extension function is meant for String, so the receiver type must be String.

4fill in blank

hard

Fill both blanks to create an extension function repeatPrint for Int that prints a message multiple times.

Kotlin

fun Int.[1](message: String) {
    for (i in 1..[2]) {
        println(message)
    }
}

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

ArepeatPrint

BtimesPrint

Cthis

DprintTimes

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong function name.

Using a fixed number instead of the receiver value in the loop.

The function name is repeatPrint (A). The number of repetitions is the receiver Int, so use this (C) in the loop.

5fill in blank

hard

Fill in the blanks to create an extension function isLongerThan for String that checks if the string length is greater than a given number.

Kotlin

fun String.[1](length: Int): Boolean {
    return this.[2] > length
}

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

AisLongerThan

Blength

Ccount

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using count or size which are not properties of String.

Forgetting to compare the length with the parameter.

The function name is isLongerThan (A). To get the string length, use the length property (B).