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

20 Mentors

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

8,596 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.

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Exercism is a great website

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 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 Rajesh Khadka

Rajesh Khadka Twitter

I love to share the knowledge. Kotlin similarities with other modern programming language brought me into it. Currently working on building mathematical foundations for data science.
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 Uzi Landsmann

Uzi Landsmann https://github.com/uzilan

I have been a developer for about 15 years, working daily with Java. I love learning new languages and am trying to learn and adopt a functional programming style.
Avatar of Mike Gehard

Mike Gehard My musings on software.

I love writing Kotlin because it has some of the power of Scala without all of the type system complexity. It is a breath of fresh air in the Java ecosystem for those of us that like the JVM but don't like Java.
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.
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.

Rail Fence Cipher
medium
cryptography
algorithms
strings
transforming
Perfect Numbers
easy
enumerations
exception handling
filtering
integers
math
List Ops
hard
filtering
functional programming
generics
lists
loops
Change
hard
algorithms
exception handling
integers
lists
Yacht
easy
enums
functional programming
lists
pattern matching
D&D Character
easy
integers
randomness
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 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 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 Denys M

Denys M

[Mobile] Software engineer and Kotlin enthusiast.

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