40 Top Kotlin Interview Questions and Answers in 2023 Updated

The process of automatically determining a variable’s or expression’s type from its value is known as type inference. When variables are first declared in Kotlin, type inference determines their type as well as the return type of functions. Companion Objects are required in Kotlin because Kotlin doesn’t have static members or member functions, unlike Java or C#. In java to store data items, we create a class by setting the variables.

kotlin developer interview questions

This question can provide insight into a candidate’s practical use of these classes, and their proficiency in the language’s features designed to streamline coding efforts. Inline function instruct compiler to insert complete body of the function wherever that function got used in the code. To use an Inline function, all you need to do is just add an inline keyword at the beginning of the function declaration. By default, the type of arguments of a constructor in val. If you want to throw NullPointerException when the value of the variable is null, then you can use the null check or !!

How does null safety work in Kotlin?

The name of the bytecode file will be MainKt.class and this file will be executed by the JVM. To group data by key in Kotlin, you must first convert the data into a map. From there, you can use the groupBy function to group all of the data in the map by key.

kotlin developer interview questions

Normally, properties declared as having a non-null type must be initialized in the constructor. Is used to check if the value of the variable is null or not. If it is null then null will be returned otherwise it will return the desired value. Just like Java, the Kotlin code is also compiled into the Java bytecode and is executed at runtime by the Java Virtual Machine i.e. When a Kotlin file named Main.kt is compiled then it will eventually turn into a class and then the bytecode of the class will be generated.

Top Kotlin Interview Questions and Answers in 2023

An infix function is used to call the function without using any bracket or parenthesis. You need to use the infix keyword to use the infix function. Learn more about the suspend function from MindOrks blog . Learn more about Primary and Secondary constructors from MindOrks blog . Learn more about the difference between lateinit and lazy from MindOrks blog . Now click on the Decompile button to get your Java code from the bytecode.

kotlin developer interview questions

Before switching to DevSkiller, their screening process consisted of a phone interview with HR followed up with a technical phone interview then a test and technical interview. After that, there was still another interview with HR and the hiring manager before an offer was made. The biggest obstacle they wanted to overcome was the number of unnecessary technical interviews that took place. Once CodeValue successfully implemented DevSkiller, they were able to reduce the time to hire by approximately 50% while hiring 2.8x more developers from the same candidate pool.

Part 1 – Basic Kotlin interview questions with answers

Each of these libraries provides important functionality for building complex applications in Kotlin. Kotlin offers several advantages over Java, including greater flexibility, readability, and more concise syntax. Additionally, Kotlin supports modern programming paradigms such as functional programming, which Java doesn’t fully support.

If you want to declare the immutable variable, you should use val because val variables can’t be changed once you have assigned them. The main function is the entry point of every Kotlin program. In Kotlin we can choose not to write the main function inside the class.

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This means we can have a long-running task, which can be executed one by one. We can pause it any number of times and resume it when required. Now, click on the Decompile button to get your Java code from the bytecode. In Kotlin, we don’t have https://wizardsdev.com/en/vacancy/android-kotlin-developer/ a ternary operator like Java, but we can use the functionality of the ternary operator by using if-else or Elvis operator. If you do not have any annotations or modifiers , you can omit the constructor keyword like the following example.

The default statement in a when is represented using the else statement.

List down the visibility modifiers available in Kotlin. What’s the default visibility modifier?

Apart form Android app development, that’s another reason I have been suggesting Java developer to learn Kotlin in 2023. Now coming back to questions, they are very simple and just test your basic Kotlin knowledge. Support of Extension- In Java, one can’t avail of extension functions. However, in Kotlin, there is strong support for extension functions making the overall process and code language clear.

  • On the other hand, var can be reassigned with the same data type value.
  • Var – value/reference assigned to a variable can be changed at any point of time.
  • The variable declaration with var and the variable declaration with val is used for different purposes.
  • It can be compiled either using Java source code and LLVM compiler.
  • We cannot just transfer objects to activities in Android.
  • In Java, static members are treated very differently than object members.

Furthermore kotlin.collections.List is an interface implemented among others by java.util.ArrayList. It’s also extended by kotlin.collections.MutableList to be used when a collections that allows for item modification is needed. If you do not specify any visibility modifier, public is used by default, which means that your declarations will be visible everywhere. Public is the default if nothing else is specified explicitly. These functions produce a Set instead of a List and should be a little bit more efficient than distinct. The first call to the lambda here will be with parameters 1 and 2.

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