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 secondary constructor must delegate to the primary one.

The primary constructor must delegate to the secondary one.

Both constructors must initialize the same properties.

The secondary constructor overrides the primary one.

None

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

methodName(classInstance)

call classInstance.methodName

classInstance::methodName()

classInstance.methodName()

None

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

To define inner classes.

To hold properties and methods that are shared across instances.

To create methods that must be overridden.

To create a class hierarchy.

None

How many primary constructors can a Kotlin class have?

As many as needed.

Two.

None.

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 directly access a property value.

To initialize class properties.

To perform calculations or logic before returning a property.

To hide a property from other classes.

None

What is a nested class in Kotlin?

A class that extends another class.

A class defined within a function.

A class that implements an interface.

A class defined within another class.

None

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

create instance MyClass(123)

val instance = MyClass()

var instance = MyClass.newInstance(123)

val instance = MyClass(123)

None

10.

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

To assign a default value.

To make the parameter optional.

To create an immutable property.

To make the property mutable.

None

11.

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

class MyClass constructor(number: Int) {}

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

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

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

None

12.

What is an object in Kotlin?

A Kotlin file containing functions.

A blueprint for creating classes.

A parent class for all Kotlin classes.

A self-contained module of functionality.

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?

nested

class

static

inner

None

15.

Which statement is true about companion objects in Kotlin?

They must be declared as ‘static’.

Each instance has its own companion object.

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?

val propertyName: Type get()

fun get()

get propertyName()

var propertyName: Type get

None

17.

What is the purpose of an initializer block in Kotlin?

To execute code before the primary constructor.

To override methods from a superclass.

To perform initialization tasks after the constructor.

To define default values for properties.

None

18.

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

this

self

current

super

None

19.

What is a primary constructor in Kotlin?

A constructor declared outside the class body.

A constructor that can only be used once.

A constructor that initializes a class with default values.

A constructor declared in the class header.

None

20.

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

customer Customer()

create Customer customer

var customer = Customer()

val customer = new Customer()

None

21.

How do you declare a class in Kotlin?

define MyClass

class MyClass : ParentClass

class MyClass extends ParentClass

declare MyClass()

None

22.

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

To allow direct access to class properties.

To store data outside the class for easy access.

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

To create multiple classes with the same properties.

None

23.

Which of the following best defines a class in Kotlin?

A class is a function in Kotlin.

A class is used to store user input.

A class is a blueprint for creating objects.

A class is a module of reusable code.

None