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Kotlin

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Kotlin is a pragmatic programming language for JVM and Android that combines OO and functional features and is focused on interoperability, safety, clarity and tooling support.
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Track mentors

21 Mentors

Our mentors are friendly, experienced Kotlin developers who will help teach you new techniques and tricks.
Track students

9,330 Students

Join thousands of students who have enjoyed learning and improving their skills by taking this track.
Track exercises

84 Exercises

Hundreds of hours have gone into making these exercises fun, useful, and challenging to help you enjoy learning.

About Kotlin

fun getGreeting(): String {
    return "Hello, World!"
}

Kotlin was designed and developed by JetBrains, the company behind IntelliJ. It is a language that runs on the JVM which can target versions 6+ (including the Android platform). JetBrains wanted to use a statically typed language which can remove Java boilerplate code, provide modern functional paradigms, and had seamless two-way Java interoperability with their existing codebase. The JVM already had alternate languages like Groovy and Scala but neither fit the bill with their desired criteria, so they built Kotlin.

Kotlin syntax is similar to Scala and Swift but pulls in the best-of-breed features from other languages such as C# and Groovy. Kotlin took a pragmatic approach at features included in the language by only providing functionality that has been proven to be useful for developers. With this decision they implemented a subset of features of Scala with the intent that it will provide more maintainable code with an easier learning curve for developers looking for a "better Java".

JetBrains has a dedicated team of developers working on Kotlin with the codebase available on Github.

Join the Kotlin track

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What I like about it is that I am able to solve the challenges in a TDD way working in a environment that I am familiar (my own PC not a browser IDE) and the cherry on the top of the cake is that I have access to code reviews.

Relaxed. Encouraging. Supportive.

Meet the Kotlin Track mentors

Once you join the Kotlin language track, you will receive support and feedback from our team of mentors. Here are the bios of a few of the mentors of this track.

Avatar of Robin Roschlau

Robin Roschlau Twitter

I've been slightly addicted to Kotlin ever since I first used it, coming from Java a few years ago, so much so that I started a Kotlin User Group in my area and am regularly holding talks about it.
Avatar of Gurpreet Singh

Gurpreet Singh Website

I am an Android Developer based out of New Delhi, and have been working with Kotlin for over a year. I'm particularly interested in Functional & Reactive programming paradigm and like to share my knowledge and learn from others.
Avatar of Sinuhe Jaime

Sinuhe Jaime https://github.com/sierisimo

I'm a geek doing a lot of things, including Kotlin. I've using the language for 3 years now but still learning everyday
Avatar of Adrian Spanu

Adrian Spanu https://github.com/aspanu

I work as a software engineer full time. Although I've never worked professionally in Kotlin, I've really enjoyed the language and I generally use it for interview problems or personal projects. I'm looking forward to helping others with it as I learn along myself.
Avatar of Severin Rudie

Severin Rudie https://github.com/Baron-Severin

I'm a full time Android developer at Mozilla, and I've been working professionally in Kotlin for about 2.5 years now. Kotlin mentor, Rust student.
Avatar of Alex Ahern

Alex Ahern https://github.com/aahern

I work as an Android developer on one of the oldest apps in the UK Play Store. We have been using Kotlin as our primary language for around a year now, and I'd like to help others develop their skills while at the same time developing my own.
Fun. Challenging. Interesting

Community-sourced Kotlin exercises

These are a few of the 84 exercises on the Kotlin track. You can see all the exercises here.

Resistor Color Duo
easy
lists
Clock
medium
equality
integers
logic
object oriented programming
strings
time
Two Fer
easy
conditionals
strings
Linked List
medium
algorithms
generics
lists
Pangram
easy
pattern matching
regular expressions
strings
Grade School
medium
conditionals
lists
maps
sorting
strings
Passionate. Knowledgeable. Creative.

Meet the Kotlin Track maintainers

The Kotlin Maintainers are the brains behind the Kotlin Track. They spend their spare time creating interesting and challenging exercises that we can all learn from. We are incredibly grateful for their hard work. Here are the bios of a few of the maintainers of this track.

Avatar of Elena Parovyshnaia

Elena Parovyshnaia

Staying with Java since 1.0, currently a Kotlin fan. Experienced in explaining things. Eager learner. Enthusiastic in putting things in order, evolving an infrastructure and processes, easing work for a community.
Avatar of Sam Warner

Sam Warner

I am a software developer and consultant working for Black Pepper Software, a software company based in Leamington Spa, England. I'm a recent Computer Science graduate from the University of Warwick, and love all things to do with computers!
Avatar of Mike Gehard

Mike Gehard

Long time software developer, recovering chemical engineer. I love helping folks along their path because I learn something new every time.
Avatar of Denys M

Denys M

[Mobile] Software engineer and Kotlin enthusiast.

Get started with the Kotlin track. As with everything on Exercism, it's 100% free!

Join the Kotlin Track