Data classes for value holders in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a data class named Person with two properties: name and age.

Kotlin

data class Person([1] name: String, val age: Int)

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

Aval

Bvar

Cfun

Dclass

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'var' instead of 'val' for properties in data classes.

Trying to use 'fun' or 'class' inside the parameter list.

In Kotlin data classes, properties are usually declared with val to make them read-only.

2fill in blank

medium

Complete the code to create an instance of the Person data class with name "Alice" and age 30.

Kotlin

val person = Person([1] = "Alice", age = 30)

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Aname

BPerson

Cage

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'age' instead of 'name' for the first argument.

Trying to use 'val' or 'Person' as argument names.

The first argument is the name property, so we assign "Alice" to name.

3fill in blank

hard

Fix the error in the code to correctly override the toString method in the data class.

Kotlin

data class Person(val name: String, val age: Int) {
    override fun [1](): String {
        return "Person(name=$name, age=$age)"
    }
}

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AtoStr

BtoString

Cstringify

Dprint

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect method names like 'toStr' or 'stringify'.

Trying to override 'print' instead of 'toString'.

The method to override for string representation is toString().

4fill in blank

hard

Fill both blanks to create a copy of a Person instance with a new age.

Kotlin

val olderPerson = person.[1]([2] = person.age + 1)

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Acopy

Bage

Cname

Dclone

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'clone' instead of 'copy'.

Changing 'name' instead of 'age'.

The copy function creates a new instance with modified properties. We change the age property.

5fill in blank

hard

Fill all three blanks to create a data class with default values and a method that returns a greeting.

Kotlin

data class Person(val name: String = [1], val age: Int = [2]) {
    fun greet() = "Hello, my name is $[3]"
}

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

A"Unknown"

B0

Cname

D"Guest"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string literal instead of the property name in the greeting.

Setting default age to a string instead of a number.

Default name is set to "Guest", default age to 0, and the greet method uses the name property.