Kotlin

Kotlin is a programming language created in 2011 by Andrey Breslav.

#25on PLDB	12Years Old	130.1kUsers
99Books	16Papers	901kRepos

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Kotlin is a statically-typed programming language that runs on the Java virtual machine and also can be compiled to JavaScript source code or use the LLVM compiler infrastructure. Its primary development is from a team of JetBrains programmers based in Saint Petersburg, Russia. While the syntax is not compatible with Java, Kotlin is designed to interoperate with Java code and is reliant on Java code from the existing Java Class Library, such as the collections framework. Read more on Wikipedia...

Kotlin website
Kotlin Wikipedia page
Kotlin is developed on GitHub and has 43,795 stars
PLDB has 2 documentation sites for Kotlin: kotlinlang.org, devdocs.io
There are at least 901,474 Kotlin repos on GitHub
Kotlin first developed in JetBrains
PLDB estimates there are currently 5k job openings for Kotlin programmers.
file extensions for Kotlin include kt, kts and ktm
Kotlin on Twitter
The Google BigQuery Public Dataset GitHub snapshot shows 6k users using Kotlin in 8k repos on GitHub
Check out the 138 Kotlin meetup groups on Meetup.com.
There are 61,654 members in the Kotlin subreddit
There are 275 Project Euler users using Kotlin
In the 2021 StackOverflow developer survey Kotlin programmers reported a median salary of $55,071. 8% of respondents reported using Kotlin. 6,866 programmers reported using Kotlin, and 10,691 said they wanted to use it
Explore Kotlin snippets on Rosetta Code
Kotlin ranks #48 in the TIOBE Index
ANTLR grammar for Kotlin
Monaco package for syntax highlighting Kotlin
Pygments supports syntax highlighting for Kotlin
GitHub supports syntax highlighting for Kotlin
There is 1 Jupyter Kernel for Kotlin
Release Notes for Kotlin
Events page for Kotlin
Frequently Asked Questions for Kotlin
Kotlin cheat sheet
Indeed.com has 5,276 matches for "kotlin developer".
kotlinlang.org was registered in 2013
See also: (16 related languages)JVM, Java Bytecode, JavaScript, Java, Scala, Groovy, C#, Gosu, Swift, LLVM IR, Android, Pascal, Perl, Eclipse, Apache Maven, Emacs
Read more about Kotlin on the web: 1. 2.
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Example from Compiler Explorer:

// Type your code here, or load an example.
fun square(num: Int): Int = num * num

Example from Riju:

println("Hello, world!")

Example from hello-world:

fun main() {
  println("Hello World")
}

Example from the Hello World Collection:

// Hello world in Kotlin

fun main(args : Array<String>) {
    println("Hello, world!")
}

Example from Linguist:

package addressbook

class Contact(
  val name : String,
  val emails : List<EmailAddress>,
  val addresses : List<PostalAddress>,
  val phonenums : List<PhoneNumber>
)

class EmailAddress(
  val user : String,
  val host : String
)

class PostalAddress(
  val streetAddress : String,
  val city : String,
  val zip : String,
  val state : USState?,
  val country : Country
) {
   assert {(state == null) xor (country == Countries["US"]) }
}

class PhoneNumber(
  val country : Country,
  val areaCode : Int,
  val number : Long
)

object Countries {
  fun get(id : CountryID) : Country = countryTable[id]
  
  private var table : Map<String, Country>? = null
  private val countryTable : Map<String, Country>
    get() {
      if (table == null) {
        table = HashMap()
        for (line in TextFile("countries.txt").lines(stripWhiteSpace = true)) {
          table[line] = Country(line)
        }
      }
      return table
    }
}

class Country(val name : String)

Example from Wikipedia:

// returns null if...
  // - foo() returns null,
  // - or if foo() is non-null, but bar() returns null,
  // - or if foo() and bar() are non-null, but baz() returns null.
  // vice versa, return value is non-null if and only if foo(), bar() and baz() are non-null
  foo()?.bar()?.baz()

Keywords in Kotlin

as as? break class continue do else false for fun if in !in interface is !is null object package return super this throw true try typealias val var when while by catch constructor delegate dynamic field file finally get import init param property receiver set setparam where actual abstract annotation companion const crossinline data enum expect external final infix inline inner internal lateinit noinline open operator out override private protected public reified sealed suspend tailrec vararg field it + - / % = += -= *= /= %= ++ -- && || ! == != === !== < > <= >= [ ] !! ?. ?: :: .. : ? ->; @ ; $ _

Feature	Supported	Token	Example
Conditionals	✓
Access Modifiers	✓
Functions	✓
Exceptions	✓
Constants	✓
Classes	✓
While Loops	✓
Booleans	✓	true false
Strings	✓	"
MultiLine Comments	✓	/* */	/* A comment */
Print() Debugging	✓	println
Line Comments	✓	//	// A comment
Type Inference	✓
Operator Overloading	✓
Interfaces	✓		interface Named { val name: String } interface Person : Named { val firstName: String val lastName: String override val name: String get() = "$firstName $lastName" }
File Imports	✓		import foo.Bar // Bar is now accessible without qualification import foo.* // everything in 'foo' becomes accessible import bar.Bar as bBar // bBar stands for 'bar.Bar'
Ternary operators	✓		// Since if statements are expressions println(if (true) true else false)
Comments	✓
Assignment	✓		table = HashMap()
Case Insensitive Identifiers	X
Semantic Indentation	X
Macros	X
Variable Substitution Syntax	X

title	author	reviews	ratings	rating
Kotlin for Android Developers: Learn Kotlin the easy way while developing an Android App	Antonio Leiva	17	117	3.81
Programming Kotlin	Stephen Samuel	4	27	3.96
Kotlin Apprentice: Beginning Programming with Kotlin	raywenderlich.com Team	0	0	0.0
Reactive Programming in Kotlin: Design and build non-blocking, asynchronous Kotlin applications with RXKotlin, Reactor-Kotlin, Android, and Spring	Rivu Chakraborty	2	14	3.93
Programming Kotlin	Venkat Subramaniam	0	1	5.00
Kotlin Programming: The Big Nerd Ranch Guide	Matthew Mathias	0	0	0.0

Books about Kotlin from ISBNdb

title	authors	year	publisher
Reactive Programming with Kotlin (First Edition): Learn Rx with RxJava, RxKotlin, and RXAndroid	Tutorial Team, raywenderlich and Sullivan, Alex	2019	Razeware LLC
Mastering Kotlin: Learn advanced Kotlin programming techniques to build apps for Android, iOS, and the web	Ebel, Nate	2019	Packt Publishing
Hands-On Serverless Applications with Kotlin: Develop scalable and cost-effective web applications using AWS Lambda and Kotlin	Trivedi, Hardik and Kulkarni, Ameya	2018	Packt Publishing
Android Development with Kotlin: Enhance your skills for Android development using Kotlin	Moskala, Marcin and Wojda, Igor	2017	Packt Publishing
Kotlin Blueprints: A practical guide to building industry-grade web, mobile, and desktop applications in Kotlin using frameworks such as Spring Boot and Node.js	Belagali, Ashish and Trivedi, Hardik and Chordiya, Akshay	2017	Packt Publishing
Kotlin Programming: The Big Nerd Ranch Guide	Skeen, Josh and Greenhalgh, David	2018-06-25T00:00:01Z	Big Nerd Ranch Guides
Android Studio 4.0 Development Essentials - Kotlin Edition: Developing Android Apps Using Android Studio 4.0, Kotlin and Android Jetpack	Smyth, Neil	2020	Payload Media
Android Programming with Kotlin for Beginners: Build Android apps starting from zero programming experience with the new Kotlin programming language	Horton, John	2019	Packt Publishing
Kotlin In-Depth: A Guide to a Multipurpose Programming Language for Server-Side, Front-End, Android, and Multiplatform Mobile (English Edition)	Sedunov, Aleksei	2022	BPB Publications
Android Studio 4.2 Development Essentials - Kotlin Edition: Developing Android Apps Using Android Studio 4.2, Kotlin and Android Jetpack	Smyth, Neil	2021	Payload Media
Kotlin Apprentice (Second Edition): Beginning Programming with Kotlin	Tutorial Team, raywenderlich and Galata, Irina and Shapiro, Ellen and Howard, Joe	2019-10-01T00:00:01Z	Razeware LLC
Android Programming with Kotlin for Beginners: Build Android apps starting from zero programming experience with the new Kotlin programming language	Horton, John	2019-04-30T00:00:01Z	Packt Publishing
Mastering Kotlin: Learn advanced Kotlin programming techniques to build apps for Android, iOS, and the web	Ebel, Nate	2019	Packt Publishing
Kotlin Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)	Greenhalgh, David and Skeen, Josh	2021	Big Nerd Ranch Guides
Functional Programming in Kotlin	Vermeulen, Marco and Bjarnason , Rúnar and Chiusano , Paul	2021	Manning
Kotlin in Action	Jemerov, Dmitry and Isakova, Svetlana	2017	Manning
Programming DSLs in Kotlin	Subramaniam, Venkat	2021	Pragmatic Bookshelf
Kotlin Apprentice (Third Edition): Beginning Programming with Kotlin	Tutorial Team, raywenderlich and Galata, Irina and Gonda, Victoria and Howard, Joe and Shapiro, Ellen	2021	Razeware LLC
Android Studio Arctic Fox Essentials - Kotlin Edition: Developing Android Apps Using Android Studio 2020.31 and Kotlin	Smyth, Neil	2021	Payload Media, Inc.
Kotlin Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)	Greenhalgh, David and Skeen, Josh	2021	Big Nerd Ranch Guides
Kotlin for Android App Development (Developer's Library)	Sommerhoff, Peter	2018	Addison-Wesley Professional
Functional Programming in Kotlin	Vermeulen, Marco and Bjarnason, Rúnar and Chiusano, Paul	2021	Manning Publications
Learn Kotlin for Android Development: The Next Generation Language for Modern Android Apps Programming	Späth, Peter	2019	Apress
Learn Kotlin Programming: A comprehensive guide to OOP, functions, concurrency, and coroutines in Kotlin 1.3, 2nd Edition	Samuel, Stephen and Bocutiu, Stefan	2019	Packt Publishing
Learn Kotlin for Android Development: The Next Generation Language for Modern Android Apps Programming	Späth, Peter	2019-05-30T00:00:01Z	Apress
Programming Kotlin Applications: Building Mobile and Server-Side Applications with Kotlin	McLaughlin, Brett	2021	Wiley
Functional Programming in Kotlin by Tutorials (First Edition): A Practical Approach to Writing Safer, More Reliable Apps	Tutorial Team, raywenderlich and Carli, Massimo	2022	Razeware LLC
Android Studio 3.6 Development Essentials - Kotlin Edition: Developing Android 10 (Q) Apps Using Android Studio 3.6, Kotlin and Android Jetpack	Smyth, Neil	2020	Payload Media
Kotlin Apprentice: Beginning Programming with Kotlin	raywenderlich.com Team and Galata, Irina and Howard, Joe and Lucas, Dick and Shapiro, Ellen	2018	Razeware LLC
Android Studio 3.2 Development Essentials - Kotlin Edition: Developing Android 9 Apps Using Android Studio 3.2, Kotlin and Android Jetpack	Smyth, Neil	2018	Payload Media, Inc.
Kotlin Programming By Example: Build real-world Android and web applications the Kotlin way	Adelekan, Iyanu	2018	Packt Publishing
Reactive Programming in Kotlin: Design and build non-blocking, asynchronous Kotlin applications with RXKotlin, Reactor-Kotlin, Android, and Spring	Chakraborty, Rivu	2017-12-05T00:00:01Z	Packt Publishing
Mastering High Performance with Kotlin: Overcome performance difficulties in Kotlin with a range of exciting techniques and solutions	Kucherenko, Igor	2018	Packt Publishing
The First Line of Code: Android Programming with Kotlin	Guo, Lin	2022	Springer
Kotlin Standard Library Cookbook: Master the powerful Kotlin standard library through practical code examples	Urbanowicz, Samuel	2018	Packt Publishing
Kotlin Programming Cookbook: Explore more than 100 recipes that show how to build robust mobile and web applications with Kotlin, Spring Boot, and Android	Roy, Aanand Shekhar and Karanpuria, Rashi	2018	Packt Publishing
Reactive Programming with Kotlin (Second Edition): Learn RX with RxJava, RxKotlin and RxAndroid	Tutorial Team, raywenderlich and Sullivan, Alex	2021	Razeware LLC
Easy Minecraft® Mod Programming: Learn to Code Minecraft® Mods with Kotlin	Norman, Michael D. and Norman, Isaac S.	2018	CreateSpace Independent Publishing Platform
Kotlin In-Depth [Vol-I]: A Comprehensive Guide to Modern Multi-Paradigm Language (English Edition)	Sedunov, Aleksei	2020	BPB Publications
Hands-On Object-Oriented Programming with Kotlin: Build robust software with reusable code using OOP principles and design patterns in Kotlin	Khan, Abid and Kucherenko, Igor	2018-10-31T00:00:01Z	Packt Publishing
Kotlin Quick Start Guide: Core features to get you ready for developing applications	Devcic, Marko	2018	Packt Publishing
Kotlin Programming Journal: Notebook For Kotlin Programming: Blank Ruled Notebook / Lined Journal Gift For Kotlin Programmers, 120 pages, 6x9 inches, Matte.	Publishing, Dascity	2019-12-20T00:00:01Z	Independently published
Kotlin At a Glance	Saxena, Swati	2019	BPB Publications
Fundamental Kotlin	Miloš Vasić	2016
Beginners Guide To Kotlin Programming	John Hunt	2021	Springer International Publishing AG
Hands-on Reactive Programming With Kotlin	Abid. Roy Khan (aanand Shekhar. Iglesias, Juan Antonio Medina.)	2019
Kotlin Programming	Josh Skeen; David Greenhalgh	20180809	Pearson Technology Group
Kotlin Cookbook	Ken Kousen	20191114	O'Reilly Media, Inc.
Functional Kotlin	Mario Arias; Rivu Chakraborty	23-02-2018	Packt Publishing
Kotlin Programming	Bruce Herbert	2019	Independently Published
Programming Kotlin	Venkat Subramaniam	20190912	O'Reilly Media, Inc.
Kotlin For Beginners	Peter Sommerhoff
Head First Kotlin	Dawn Griffiths and David Griffiths	2019	O'reilly Media
Programming Kotlin Applications	Brett McLaughlin	2020	John Wiley & Sons
Head First Kotlin	Dawn Griffiths; David Griffiths	20190213	O'Reilly Media, Inc.
Learn Kotlin Programming	Stephen Samuel; Stefan Bocutiu	29-05-2019	Packt Publishing
Kotlin Programming Cookbook	Aanand Shekhar Roy; Rashi Karanpuria	25-01-2018	Packt Publishing
Java to Kotlin	Duncan McGregor; Nat Pryce	20210816	O'Reilly Media, Inc.
Programming Kotlin Applications	Brett McLaughlin	20201209	Wiley Professional Development (P&T)
Programming DSLs in Kotlin	Venkat Subramaniam	20210323	O'Reilly Media, Inc.
Kotlin Programming By Example	Iyanu Adelekan	28-03-2018	Packt Publishing
Reactive Programming in Kotlin	Rivu Chakraborty	43074	Packt Publishing
Kotlin Standard Library Cookbook	Samuel Urbanowicz	30-07-2018	Packt Publishing
Programming Android with Kotlin	Pierre-Olivier Laurence; Amanda Hinchman-Dominguez; G. Blake Meike; Mike Dunn	20211206	O'Reilly Media, Inc.
The Joy of Kotlin	Pierre-Yves Saumont	20190421	Simon & Schuster
Kotlin Basics: The Ultimate Beginner's Guide To Learn Kotlin Programming Step By Step	Moaml Mohmmed	2019-08-16	Independently Published
Beginner's Guide to Kotlin Programming	John Hunt	20211008	Springer Nature
Learn to Program with Kotlin	Tim Lavers	20210518	Springer Nature
Mastering Android Development with Kotlin	Milos Vasic	43047	Packt Publishing
Hands-On Microservices with Kotlin	Juan Antonio Medina Iglesias	29-01-2018	Packt Publishing
Learn Android Studio 3 with Kotlin	Ted Hagos	20181112	Springer Nature
Kotlin Design Patterns and Best Practices	Alexey Soshin; Anton Arhipov	21-01-2022	Packt Publishing
Android Studio Bumble Bee Essentials - Kotlin Edition	Neil Smyth	2022-02-18	Payload Media, Inc.
Hands-On Design Patterns with Kotlin	Alexey Soshin	15-06-2018	Packt Publishing
Kotlin and Android Development featuring Jetpack	Michael Fazio	20210615	O'Reilly Media, Inc.
Learning Kotlin by building Android Applications	Eunice Obugyei; Natarajan Raman	20180625	Packt Publishing
Hands-On Serverless Applications with Kotlin	Hardik Trivedi; Ameya Kulkarni	29-09-2018	Packt Publishing
Android Studio 4.1 Development Essentials - Kotlin Edition	Neil Smyth	2020-12-08	Payload Media, Inc.
Android Studio 3.6 Development Essentials - Kotlin Edition	Neil Smyth	2020-04-30	Packt Publishing
Android Studio 4.0 Development Essentials - Kotlin Edition	Neil Smyth	2020	Packt Publishing
Android Studio 3.6 Development Essentials - Kotlin Edition	Neil Smyth	2020-04-01	Payload Media, Inc.
Android Studio 3.5 Development Essentials - Kotlin Edition	Neil Smyth	2019-05-17	Packt Publishing
Android Studio 4.2 Development Essentials - Kotlin Edition	Neil Smyth	2021-08-10	Packt Publishing
Simplifying Application Development with Kotlin Multiplatform Mobile	Róbert Nagy	44624	Packt Publishing
Hands-On Object-Oriented Programming with Kotlin	Abid Khan; Igor Kucherenko	31-10-2018	Packt Publishing
Kotlin for Enterprise Applications using Java EE	Raghavendra Rao K	30-11-2018	Packt Publishing
Android Studio Arctic Fox Essentials - Kotlin Edition	Neil Smyth	2021-10-18	Packt Publishing
Building Applications with Spring 5 and Kotlin	Milos Vasic	18-05-2018	Packt Publishing
Android Studio 4. 0 Development Essentials - Kotlin Edition	Neil Smyth	2020
Android Studio 3. 6 Development Essentials - Kotlin Edition	Neil Smyth	2020	Packt Publishing, Limited
Kickstart Modern Android Development with Jetpack and Kotlin	Catalin Ghita	20220524	Packt Publishing
Cracking Kotlin Interview: Solutions to Your Basic to Advanced Programming Questions	Swati Saxena	04/2020	BPB Publications
Kotlin In-depth [Vol-II]: A comprehensive guide to modern multi-paradigm language	Aleksei Sedunov	03/2020	BPB Publications

title	authors	year	citations	influentialCitations
An empirical study on quality of Android applications written in Kotlin language	Bruno Góis Mateus and Matias Martinez	2018	26	5
Characterizing the transition to Kotlin of Android apps: a study on F-Droid, Play Store, and GitHub	Riccardo Coppola and Luca Ardito and Marco Torchiano	2019	17	3
Are you still smelling it?: A comparative study between Java and Kotlin language	Matheus Flauzino and Júlio Veríssimo and Ricardo Terra and Elder Cirilo and Vinicius H. S. Durelli and R. Durelli	2018	16	3
A COMPARATIVE STUDY: JAVA VS KOTLIN PROGRAMMING IN ANDROID APPLICATION DEVELOPMENT	Madhurima Banerjee and Subham Bose and A. Kundu and Madhuleena Mukherjee	2018	16	1
On the adoption, usage and evolution of Kotlin features in Android development	B. Mateus and Matias Martinez	2019	11	0
Detecting anomalies in Kotlin code	T. Bryksin and V. Petukhov and Kirill Smirenko and Nikita Povarov	2018	8	1
Using Large-Scale Anomaly Detection on Code to Improve Kotlin Compiler	T. Bryksin and V. Petukhov and Ilya Alexin and Stanislav Prikhodko and A. Shpilman and V. Kovalenko and Nikita Povarov	2020	5	0
ReduKtor: How We Stopped Worrying About Bugs in Kotlin Compiler	Daniil Stepanov and M. Akhin and Mikhail A. Belyaev	2019	4	0
Kotlin language for science and Kmath library	A. Nozik	2019	4	0
Transitioning to Teaching Android With Kotlin and Jetpack Components	A. Esakia	2020	2	1
A Severity-Based Classification Assessment of Code Smells in Kotlin and Java Application	Aakanshi Gupta and Nidhi Kumari Chauhan	2021	2	0
Spring Boot with Groovy, Scala, and Kotlin	K. Reddy	2017	1	0
How does Migrating to Kotlin Impact the Run-time Efficiency of Android Apps?	Michael Peters and Gian Luca Scoccia and I. Malavolta	2021	1	0
Kotlin coroutines: design and implementation	Roman Elizarov and Mikhail A. Belyaev and M. Akhin and Ilmir Usmanov	2021	1	0
Why did developers migrate Android Applications from Java to Kotlin	Matias Martinez and B. Mateus	2020	1	0
Type-Centric Kotlin Compiler Fuzzing: Preserving Test Program Correctness by Preserving Types	Daniil Stepanov and M. Akhin and Mikhail A. Belyaev	2020	1	0

Kotlin - Programming language

Keywords in Kotlin

Language features

Books about Kotlin on goodreads

Books about Kotlin from ISBNdb

Publications about Kotlin from Semantic Scholar