Interview questions for Kotlin

1) What is Kotlin?

Kotlin is a statically-typed programming language which runs on the JVM. It can be compiled either using Java source code and LLVM compiler.

2) Who is the developer of Kotlin?

Kotlin was developed by JetBrains.

3) Why you should switch to Kotlin from Java?

Kotlin language is quite simple compared to Java. It reduces may redundancies in code as compared to Java. Kotlin can offer some useful features which are not supported by Java.

4) Tell three most important benefits of using Kotlin?

1. Kotlin language is easy to learn as its syntax is similar to Java.
2. Kotlin is a functional language and based on JVM. So, it removes lots of boiler plate
3. It is an expressive language which makes code readable and understandable.

5. Is there a ternary operator like in Java?

No, there isn’t, but what a ternary operator does can be achieved through an if-else expression.

6. What’s the difference between val and var in Kotlin?

Both are used for declaring a variable. However, while val is a final variable that is immutable and can be initialized only once, var is a general variable that can be assigned multiple times.

7. What are the basic data types in Kotlin?

Numbers, characters, Booleans, arrays, and strings.

8. How many constructors are there in Kotlin?

A constructor’s main role is to initialize the properties of a class. In Kotlin, there can be a primary constructor and one or more secondary constructors.

9. What are the extension methods that Kotlin provides to the Java.io file list?

• bufferedReader():read contents of a file to BufferedReader
• readBytes() : read contents of a file to ByteArray
• readText(): read contents of a file to a single String
• forEachLine() : read a file line by line in Kotlin
• readLines(): read lines in a file to List

10. What is the Init Block?

It’s the initializer block and the code inside of it is executed when the primary constructor is instantiated.

11. Is new a keyword in Kotlin?

No, it’s not and it doesn’t have to be used to instantiate a class.

12. Are there primitives in Kotlin?

In a nutshell, there are no out-of-the-box primitives in Kotlin – they can’t be created at a code level. Given that Kotlin has been designed to cooperate with Java and the JVM seamlessly, certain types like int or float can act like primitives in certain cases.

13. Is there an equivalent for switch in Kotlin?

Yes, there is. The When keyword is used instead.

14. What are deconstructing declarations?

Kotlin comes with a functionality that allows developers to assign multiple values to variables. This kind of syntax allows for creating multiple variables that can be used independently at once.

15. Why do you think one should choose Kotlin over Java?

Frequently hiring managers to pose such inquiries to gauge the profundity of the job searchers. Since contrasting two amazing programming languages can never hold up under productive outcomes, you ought to rather talk about their upsides and downsides for exhibiting your aptitude. Java is as yet a superior language that is used to create enterprise-grade customer applications because of its huge list of robust features and ceaseless network support.
Be that as it may, despite being another language, it interoperates pleasantly with Java programming. It permits code developers to make inventive applications without composing many lines of code. Kotlin’s solid type interfaces make it a strong decision for creating cutting edge applications. Additionally, since it very well may be likewise utilized for creating iOS applications, engineers don’t have to grasp new stacks any longer.

16. Can you use primitive types for example- int, float, and double in Kotlin?

If I were to say at only the language level, we cannot use the afore-mentioned types. However, on the upside, the JVM’s bytecode which is compiled can surely have them.

17.  What’s the entry point of every Kotlin Program?

It is the ‘main’ function that is an entry point of every program in Kotlin. In Kotlin we can decide not to compose the main function within the class. At the time of compiling the JVM implicitly encapsulates it within a class.
The string functions that are written as ‘Array’ are utilized to recover the order line arguments.

18. Why is it preferred to utilize Kotlin for a robust Mobile App Development?

As Kotlin improves numerous linguistic components of Java, it’s simpler to compose a succinct and all around reported code. Furthermore, since it runs legitimately on JVM, enterprises scarcely need to put resources into new tech stacks. Therefore, the money-saving advantage is phenomenal.
Additionally, Kotlin has just begun to supplant numerous Java-based Android applications, and also the iOS applications written in Swift. This scenario will just increment after some time and adjusting to Kotlin will turn into an unquestionable requirement for present-day endeavors. Along these lines, to remain in front of the opposition, mobile app developers should grasp Kotlin today.

19. What are some extensions that are available to java.io.file in the Kotlin environment?

Here is a list of some useful extensions that are available to java.io.file in the Kotlin environment
File.bufferedReader() : this extension facilitates the reading of contents of a given file in the BufferedReader
File.forEachLine() : this extension facilitates the reading of a given file in a line by line manner in the Kotlin environment
File.inputStream() : this extension helps in reading of the given contents of a file to the InputStream
File.readBytes() : this extension facilitates the reading of the contents of a file to the ByteArray
File.readLines() : this extension facilitates to read the lines of a file to the List
File.readText() : this extension helps you in the reading of contents of a given file to a single String

20. What is the interoperability of Kotlin with JavaScript?

During numerous Kotlin inquiries questions, interviewees are gotten some information about the level of adaptability Kotlin takes into account JavaScript applications. Kotlin empowers Android and iOS devs to flawlessly target JavaScript. This means you can without much of a stretch trans-compile a Kotlin program to local JavaScript code. This permits code designers to effectively make programming for the famous Node.JS stage.
Kotlin empowers developers to control all components of JS programming, for example, controlling the DOM, utilizing illustrations, dealing with the server-side, etc. Furthermore, you can use Kotlin with existing JS libraries like jQuery and React.