Kotlin Interview Questions And Answers

The following are a few top most Kotlin Interview Questions and Answers with detailed programming examples that will help you crack the Interview. The questions begin with the basics of Kotlin to advanced programming. Here, Tutorials Mania is providing you the Real-Time Interview Questions to coding questions as well to brush up your skills. Let’s have a look…

Kotlin Interview Questions

  1. What is Kotlin?
  2. Name the features that are in Kotlin but not present in Java?
  3.  Why should you switch to Kotlin from Java?
  4. What type of programming does Kotlin support?
  5. What is the use of Kotlin extension functions?
  6. What is the list of default visibility qualifiers and different types of modifiers?
  7. What is Kotlin’s target platform? And Java-kotlin interoperability is possible?
  8. How to declare a Kotlin variable?
  9. Explain the difference between Val & var declaration?
  10. Write the process to convert String to Integer?

Kotlin Interview Questions And Answers

Q) what is Kotlin?

Ans: Kotlin is a cross-platform, static type common programming language with type inference. Kotlin’s design is fully interoperable with Java & the JVM(Version) of its standard library relies on the Java class library, but type inference makes the syntax cleaner.

Q) Name a few features that are in Kotlin but not present in Java?

Ans: Kotlin has many features that do not exist in Java. The following are a few features:

  • Null safety
  • Operator overloading
  • Extension functions
  • Data classes etc

Q) Why should you switch to Kotlin from Java?

Answer:  Kotlin is a new programming language, similar to Java. It is identified by the jet brain and developed using ideas from some great other members. Kotlin is a useful coding based and simple learning programming language for writing code for existing systems. Kotlin uses Javascript and computer machine code to use the JVM environment. Based on the Java programming language, Kotlin can run in any Java-based environment, but the main environment must be the JVM. Kotlin offers many new features that are not supportable on Java.

Q) What type of programming does Kotlin support?

Ans: Kotlin supports two types of programming are shown below:

  • Object-Oriented Programming similar to Java
  • Procedural Programming

Q) What is the use of the Kotlin extension function?

Ans: Extension functions are used to extend a class without inheriting from a class.

Q) What is the list of default visibility qualifiers and different types of modifiers?

Answer: The modifier is public by default. The following are some of the types of modifiers:

  • public
  • internal
  • private
  • protected

Q) What is Kotlin’s target platform? And Java-kotlin interoperability is possible?

Answer: Kotlin’s target platform is JVM. Java is 100% interoperable with kotlin. Because both generate the same bytecode at compile-time, hence, Kotlin code can be called from Java and vice versa. 

Q) How to declare a Kotlin variable?

Ans: In the Kotlin, the variable declaration:

Val s: String = “Hello world!!”

var p = 15

Q) Explain the difference between Val and var declarations? 

Answer: Val is also called as similar to final modifiers in Java, and They can’t change. Var can be reassigned, but data types cannot be changed. The following figure shows.

Val y: string = “hello”.

Var x = 5

Q) Write the process to convert String to Integer?

Ans: The method toInt() is used to convert string to an integer. Here is an example:

fun main(args: Array<String>) {

   Val s: String = “Hello”

   var x = 7

   x = “9”.toInt()


Q) Is it possible to migrate the code from Java to Kotlin?

Answer: Yes, it is easy and possible, that Java code can be migrated to Kotlin. The JetBrains IDE must do this for conversion purposes.

What is Kotlin?

The best Kotlin Interview Questions And Answers

Q) What are the different types of constructors in Kotlin?

Answer:  There are mainly two types of constructors in Kotlin, and they are

  • Primary constructor
  • Secondary constructor
  1. Primary constructor: In this type of constructor class header is declared after the class name.
  2. Secondary constructor: These types of constructors are declared inside the body.

Q) Does Kotlin support primitive Data types?

Answer: No, Kotlin does not support primitive Data types, but Java supports.

Q) Mention the structural expressions in Kotlin?

Ans: Below is three structural expressions/formulas of Kotlin.

  1. Return: By default, It will return the values from functions.
  2. Break: It is used to  terminate loop conditions.
  3. Continue: It precedes to the next enclosing loop.

Q) What are the data classes in Kotlin? How are they defined?

Answer: In kotlin, a huge amount of data is stored, and it is defined as a data class. You need to add a keyword “data” to create a “data class. The following is an example:

data class Bus(var name: String, var authorName: String)

fun main(args: Array<String>)


Val book = Bus(“name of the book”, “any author name”)


Q) what operator is used to handle null exceptions in Kotlin?

Answer: To handle null exceptions in Kotlin, Elvis Operator is used.

Q) What are High-Level Functions or Higher-order Functions in Kotlin?

Answer: A higher-order function is a function that receives or returns another function. In Kotlin, functions are considered first-class citizens, so they can be assigned to variables and passed as arguments to other functions. This can be done with a lambda expression or a function reference.

Q. What is the Kotlin Coroutines?

Answer: In this code lab, you will learn how to use kotlin coroutines in Android apps. A coroutine is a kotlin feature that converts the asynchronous callbacks for long-running tasks, such as database and network access, to sequential code. 

Q) How to create static methods in Kotlin?

Answer: Kotlin does not have static methods, but uses the keyword object to create static methods. Hers is an example shows how to create a static method:

class kotlin {

  companion object1 {

     fun x() : Int = 50



Q) Explain the advantages and disadvantages of Kotlin?

Answer: Here are the  pros and cons while using Kotlin:

Advantages  Disadvantages
Kotlin is somewhat similar to Java and easy to learn.Kotlin does not provide static modifiers, causing problems for Java developers.
It can be used in any applications used in any device such as the desktop. Web Server and mobile phonesThe kotlin function can be declared and called in multiple places, so it can be confusing.

Q. Does Google use Kotlin?

Answer: Google has just announced that it will officially support kotlin as a “top-notch” language on Android. Kotlin is a super new programming language built by JetBrains, and it also develops JetBrains IDE, Android Studio – Google’s official developer tool.

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About Akshay Kumar Kothuri

Akshay Kumar Kothuri was born and brought up in Hyderabad. He works as an AI developer and Speaker for many technical events like Workshops, Hackathons, and Faculty Development Programs conducted across India. He is passionate about exploring the latest technologies and innovations in the field of Artificial intelligence, Machine Learning, Robotics, Chatbots, IoT, Embedded Systems, Data analytics, Vmware, and other competing technologies in software. He has good working knowledge and experience in AI-related systems. He holds a Master's degree in Embedded systems from VITS. Follow him on LinkedIn. You can also contact him at [email protected]
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