Properties with val and var in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a read-only property.

Kotlin

class Person {
    val name: String = [1]
}

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Aval

Bvar

Cfun

D"Alice"

Attempts:

3 left

💡 Hint

Common Mistakes

Using var instead of a value for assignment.

Forgetting to use quotes for string values.

The val keyword declares a read-only property. Here, name is assigned the value "Alice".

2fill in blank

medium

Complete the code to declare a mutable property.

Kotlin

class Car {
    var speed: Int = [1]
}

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

A0

B"fast"

Cval

Dfun

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning a string to an integer property.

Using val instead of var for mutable properties.

The var keyword declares a mutable property. Here, speed is initialized to 0 and can be changed later.

3fill in blank

hard

Fix the error in the property declaration to make it mutable.

Kotlin

class Book {
    [1] title: String = "Kotlin Guide"
}

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Afun

Bvar

Cval

Dconst

Attempts:

3 left

💡 Hint

Common Mistakes

Using val which makes the property read-only.

Using fun which is for functions, not properties.

Using var makes the property mutable, allowing its value to be changed after initialization.

4fill in blank

hard

Fill both blanks to declare a read-only property with a custom getter.

Kotlin

class Circle(val radius: Double) {
    val area: Double
        get() = [1] * radius [2] radius
}

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AMath.PI

B*

C+

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication for squaring.

Using val inside the getter instead of a value.

The area of a circle is calculated as π times radius squared. Here, Math.PI is multiplied by radius * radius.

5fill in blank

hard

Fill all three blanks to declare a mutable property with a backing field and custom setter.

Kotlin

class Temperature {
    var celsius: Double = [1]
        set(value) {
            field = if (value [2] [3]273.15) [3]273.15 else value
        }
}

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

A0.0

B<

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of subtraction for negative numbers.

Not using the backing field field inside the setter.

The property celsius is initialized to 0.0. The setter checks if the new value is less than absolute zero (-273.15) and sets it to -273.15 if so; otherwise, it sets the value normally.