Data types and type inference in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable with type inference holding the number 10.

Android Kotlin

val number = [1]

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

A10

B"10"

C10.0

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Putting 10 in quotes makes it a string, not a number.

Using 10.0 makes it a Double, not an Int.

The number 10 is an integer, so just writing 10 lets Kotlin infer the type Int.

2fill in blank

medium

Complete the code to explicitly declare a variable of type Double with value 3.14.

Android Kotlin

val pi: [1] = 3.14

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

AInt

BDouble

CString

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int will cause a type mismatch error.

Using String or Boolean is incorrect for numbers.

The value 3.14 is a decimal number, so the type should be Double.

3fill in blank

hard

Fix the error in the code by choosing the correct type for the variable holding true.

Android Kotlin

val isActive: [1] = true

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

AInt

BString

CBoolean

DDouble

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int or Double causes type mismatch errors.

Using String is incorrect because true is not text.

The value true is a boolean, so the variable type must be Boolean.

4fill in blank

hard

Fill both blanks to declare a mutable variable of type String with value "Hello".

Android Kotlin

var greeting: [1] = [2]

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

AString

B"Hello"

CInt

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int or Boolean types for text variables.

Not putting the string value in quotes.

The variable greeting should be a String and assigned the text "Hello".

5fill in blank

hard

Fill all three blanks to create a read-only variable with type inferred as Int and value 42.

Android Kotlin

val [1] = [2] // inferred type is [3]

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

Aanswer

B42

CInt

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string or boolean value instead of a number.

Choosing a variable name that is not descriptive.

The variable name is answer, assigned the number 42, which Kotlin infers as type Int.