Extension properties in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an extension property isEven for Int that returns true if the number is even.

Kotlin

val Int.isEven: Boolean
    get() = this [1] 2 == 0

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

A*

B/

C+

D%

Attempts:

3 left

💡 Hint

Common Mistakes

Using division (/) instead of modulus (%)

Using multiplication (*) or addition (+) operators

The modulus operator (%) returns the remainder. If the remainder when divided by 2 is 0, the number is even.

2fill in blank

medium

Complete the code to declare an extension property lastChar for String that returns the last character.

Kotlin

val String.lastChar: Char
    get() = this[1]

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

A.last()

B[0]

C.first()

D[length - 1]

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 0 which returns the first character

Using length as an index which is out of bounds

The last() function returns the last character of the string.

3fill in blank

hard

Fix the error in the extension property that returns the first half of a string.

Kotlin

val String.firstHalf: String
    get() = this.substring(0, this.length [1] 2)

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

A+

B/

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition (+) or subtraction (-) instead of division

Using multiplication (*) which increases length

To get the first half, divide the length by 2 to get the midpoint index.

4fill in blank

hard

Fill the blank to create an extension property isPalindrome for String that checks if the string reads the same forwards and backwards.

Kotlin

val String.isPalindrome: Boolean
    get() = this [1] this.reversed()

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

A==

B!=

C&&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using inequality (!=) which gives wrong result

Using logical AND (&&) or OR (||) which are not comparison operators

To check palindrome, compare the string with its reversed version using equality (==).

5fill in blank

hard

Fill all three blanks to create an extension property wordCount for String that returns the number of words separated by spaces.

Kotlin

val String.wordCount: Int
    get() = this.[1](" ").[2] [3] 0

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

Asplit

Bsize

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus (-) instead of plus (+) which can reduce count incorrectly

Using wrong functions like join or length

Split the string by spaces, get the size of the resulting list, and add 0 (no change) to get the count.