Top 10 KOTLIN Interview Questions and Answers

Authored By: Ankita Prajapati

KOTLIN is Object Oriented Programming Language prominently used in Android development. In 2019, Google made Kotlin the official language for Android apps. You must understand the basics of KOTLIN  to secure a job related to it. Read the top KOTLIN Interview Question and Answers.

Question 1: What is Kotlin?  

Answer: Programming in Kotlin, a statically typed language that utilizes the JVM, is possible. Both the Java source code and the LLVM compiler can be used to compile it.

Question 2: Why you should switch to Kotlin from Java? 

Answer: In comparison to Java, the Kotlin language is extremely easy. Compared to Java, it reduces a lot of code repetition. Some helpful features that Java does not support can be found in Kotlin. 

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Question 3: Tell three most important benefits of using Kotlin? 

Answer: Three most important benefits of using Kotlin are:-

  1.  The Java-like syntax of the Kotlin language makes it simple to learn. 
  2. A functional language built on the JVM, Kotlin. Thus, a lot of boilerplate is eliminated.
  3. Because it uses an expressive language, code can be read and understood.


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Question 4: Explain the use of the extension function.

Answer: Without having to inherit from the class, extension functions help extend classes.

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Question 5: What does ‘Null Safety’ mean in Kotlin? 

Answer: The Null Safety feature enables immediate removal of the possibility of NullPointerException occurrence. It is also feasible to distinguish between references that can be nulled and those that cannot.

Question 6: Why is Kotlin interoperable with Java?   

Answer: Kotlin uses JVM bytecode, which makes it compatible with Java. It can be directly compiled to bytecode, which reduces compile time and does not distinguish between Java and Kotlin for the JVM. 

Question 7: Is there any Ternary Conditional Operator in Kotlin Like in Java? 

Answer: The ternary conditional operator is not present in Kotlin.

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Question 8: How many constructors are available in Kotlin? 

Answer: Two constructors are available in kotlin. These are:- 

  1. Primary constructor 
  2. Secondary constructor 

Question 9: Give me the name of the extension methods Kotlin provides to

Answer: Name of extension methods that kotlin provides to are:-

  1. Use buffered reader() to read file data into BufferedReader 
  2. For reading a file’s contents to a ByteArray, use the read bytes() function. 
  3. For reading a single String, use the read text() function.  
  4. For reading a file line by line in Kotlin, use the for each line() function. 

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Question 10: What are some of the features which are there in Kotlin but not in Java? 

Answer: Here are a few key Kotlin characteristics that Java lacks: 

  1. Null Safety 
  2. Operator Overloading 
  3. Coroutines 
  4. Range expressions 
  5. Smart casts 
  6. Companion Objects 

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