Kotlin OOP Quiz – Answertopia

This quiz tests your understanding of the fundamental concepts of Object-Oriented Programming (OOP) in Kotlin. It covers key topics such as classes, objects, data encapsulation, constructors, methods, properties, companion objects, and nested classes. Each question is designed to reinforce your knowledge of how these concepts are implemented in Kotlin and how they contribute to building reusable, efficient, and organized code structures.

What will happen if a class in Kotlin has both a primary constructor and a secondary constructor?

The primary constructor must delegate to the secondary one.

The secondary constructor overrides the primary one.

Both constructors must initialize the same properties.

The secondary constructor must delegate to the primary one.

None

In Kotlin, how do you call a method of a class instance?

methodName(classInstance)

classInstance::methodName()

call classInstance.methodName

classInstance.methodName()

None

What is the purpose of the 'companion object' in a Kotlin class?

To hold properties and methods that are shared across instances.

To define inner classes.

To create methods that must be overridden.

To create a class hierarchy.

None

How many primary constructors can a Kotlin class have?

None.

Two.

As many as needed.

One.

None

What is the output of the following code snippet?

class MyClass(val x: Int) {
 init {
 println(x * 2) 
 }
}

fun main() {
 val instance = MyClass(5)
}

An error occurs

None

Which keyword is used to initialize a property with a specific value when an instance is created in Kotlin?

constructor

val

init

this

None

When should you use a custom accessor in Kotlin?

To perform calculations or logic before returning a property.

To hide a property from other classes.

To directly access a property value.

To initialize class properties.

None

What is a nested class in Kotlin?

A class that implements an interface.

A class that extends another class.

A class defined within a function.

A class defined within another class.

None

Which of the following code snippets creates an instance of a class using a secondary constructor?

val instance = MyClass(123)

create instance MyClass(123)

var instance = MyClass.newInstance(123)

val instance = MyClass()

None

10.

What is the purpose of the 'val' keyword in a primary constructor parameter?

To create an immutable property.

To make the property mutable.

To assign a default value.

To make the parameter optional.

None

11.

Which of the following Kotlin code snippets is correct for adding a secondary constructor?

class MyClass { constructor(number: Int) : this() }

class MyClass { fun constructor(number: Int) {} }

class MyClass(number: Int) { constructor() }

class MyClass constructor(number: Int) {}

None

12.

What is an object in Kotlin?

A self-contained module of functionality.

A blueprint for creating classes.

A parent class for all Kotlin classes.

A Kotlin file containing functions.

None

13.

How do you access a property of a class instance in Kotlin?

classInstance.propertyName

classInstance:propertyName

classInstance->propertyName

classInstance::propertyName

None

14.

What keyword is used to declare a nested class that can access properties of the outer class?

static

class

inner

nested

None

15.

Which statement is true about companion objects in Kotlin?

Each instance has its own companion object.

They must be declared as ‘static’.

They can contain properties and methods shared by all instances.

They can be accessed only through instances.

None

16.

How do you declare a custom getter for a property in Kotlin?

var propertyName: Type get

fun get()

val propertyName: Type get()

get propertyName()

None

17.

What is the purpose of an initializer block in Kotlin?

To define default values for properties.

To override methods from a superclass.

To execute code before the primary constructor.

To perform initialization tasks after the constructor.

None

18.

In Kotlin, which keyword is used to refer to the current class instance within a class?

this

self

super

current

None

19.

What is a primary constructor in Kotlin?

A constructor declared in the class header.

A constructor that initializes a class with default values.

A constructor that can only be used once.

A constructor declared outside the class body.

None

20.

Which of the following code snippets correctly creates an instance of a class named Customer?

var customer = Customer()

create Customer customer

val customer = new Customer()

customer Customer()

None

21.

How do you declare a class in Kotlin?

declare MyClass()

class MyClass : ParentClass

define MyClass

class MyClass extends ParentClass

None

22.

What is the purpose of data encapsulation in object-oriented programming?

To create multiple classes with the same properties.

To hide data inside a class and access it through methods.

To store data outside the class for easy access.

To allow direct access to class properties.

None

23.

Which of the following best defines a class in Kotlin?

A class is a blueprint for creating objects.

A class is a module of reusable code.

A class is a function in Kotlin.

A class is used to store user input.

None