Kotlin Kotlin Classes and Object-Oriented Programming

Question 1

What is a data class in Kotlin?

Accepted Answer

A class that automatically generates equals, hashCode, copy, and toString

Answer

A class that stores only primitive types

Answer

A class that cannot be inherited

Answer

A class used only for database storage

Question 2

What keyword makes a Kotlin class open for inheritance?

Accepted Answer

open

Answer

abstract

Answer

extends

Answer

inheritable

Question 3

Which Kotlin class type cannot be instantiated and may have abstract members?

Accepted Answer

abstract

Answer

sealed

Answer

data

Answer

inner

Question 4

What is a companion object in Kotlin?

Accepted Answer

A singleton object declared inside a class that holds class-level members

Answer

An object that accompanies a coroutine

Answer

A helper class for data serialization

Answer

An object that implements multiple interfaces

Question 5

How do you declare a primary constructor in Kotlin?

Accepted Answer

Using parameters directly after the class name

Answer

Using a `constructor()` block inside the class body

Answer

Using `init` keyword before the class name

Answer

Kotlin does not support primary constructors

Question 6

What is a sealed class in Kotlin used for?

Accepted Answer

Restricting class hierarchies to a defined set of subclasses

Answer

Encrypting class data

Answer

Preventing serialization

Answer

Allowing multiple inheritance