Kotlin (programming language)

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Kotlin
ParadigmMulti-paradigm: object-oriented, functional, imperative, block structured, declarative, generic, reflective, concurrent
Designed byJetBrains
DeveloperJetBrains
First appearedJuly 22, 2011 (2011-07-22)
Stable release2.0.0 Edit this on Wikidata / 21 May 2024 (21 May 2024)
Typing disciplineInferred, static, strong
Platform
OSCross-platform
LicenseApache License 2.0
Filename extensions.kt, .kts, .kexe, .klib
Websitekotlinlang.org
Influenced by
Influenced
V (Vlang)

Kotlin (/ˈkɒtlɪn/) is a cross-platform, statically typed, general-purpose high-level programming language with type inference. Kotlin is designed to interoperate fully with Java, and the JVM version of Kotlin's standard library depends on the Java Class Library, but type inference allows its syntax to be more concise. Kotlin mainly targets the JVM, but also compiles to JavaScript (e.g., for frontend web applications using React) or native code via LLVM (e.g., for native iOS apps sharing business logic with Android apps). Language development costs are borne by JetBrains, while the Kotlin Foundation protects the Kotlin trademark.

On 7 May 2019, Google announced that the Kotlin programming language was now its preferred language for Android app developers. Since the release of Android Studio 3.0 in October 2017, Kotlin has been included as an alternative to the standard Java compiler. The Android Kotlin compiler produces Java 8 bytecode by default (which runs in any later JVM), but lets the programmer choose to target Java 9 up to 20, for optimization, or allows for more features; has bidirectional record class interoperability support for JVM, introduced in Java 16, considered stable as of Kotlin 1.5.

Kotlin has support for the web with Kotlin/JS, either through a classic interpreter-based backend which has been declared stable since version 1.3, or an intermediate representation-based backend which has been declared stable since version 1.8. Kotlin/Native (for e.g. Apple silicon support) is considered beta since version 1.3.

History

A 2D picture of the Kotlin mascot A 3D picture of the Kotlin mascot

Name

The name is derived from Kotlin Island, a Russian island in the Gulf of Finland, near St. Petersburg. Andrey Breslav, Kotlin's former lead designer, mentioned that the team decided to name it after an island, just like the programming language Java was named after the Indonesian island of Java (though the language's name is said to have been inspired by "java" the American slang term for coffee, which itself is derived from the island name).

Development

In July 2011, JetBrains unveiled Project Kotlin, a new language for the JVM, which had been under development for a year. JetBrains lead Dmitry Jemerov said that most languages did not have the features they were looking for, with the exception of Scala. However, he cited the slow compilation time of Scala as a deficiency. One of the stated goals of Kotlin is to compile as quickly as Java. In February 2012, JetBrains open sourced the project under the Apache 2 license.

JetBrains hoped that the new language would drive IntelliJ IDEA sales.

The first commit to the Kotlin Git repository was on November 8, 2010.

Kotlin 1.0 was released on February 15, 2016. This is considered to be the first officially stable release and JetBrains has committed to long-term backwards compatibility starting with this version.

At Google I/O 2017, Google announced first-class support for Kotlin on Android.

Kotlin 1.2 was released on November 28, 2017. Sharing code between JVM and JavaScript platforms feature was newly added to this release (multiplatform programming is by now a beta feature upgraded from "experimental"). A full-stack demo has been made with the new Kotlin/JS Gradle Plugin.

Kotlin 1.3 was released on 29 October 2018, adding support for coroutines for use with asynchronous programming.

On 7 May 2019, Google announced that the Kotlin programming language is now its preferred language for Android app developers.

Kotlin 1.4 was released in August 2020, with e.g. some slight changes to the support for Apple's platforms, i.e. to the Objective-C/Swift interop.

Kotlin 1.5 was released in May 2021.

Kotlin 1.6 was released in November 2021.

Kotlin 1.7 was released in June 2022, including the alpha version of the new Kotlin K2 compiler.

Kotlin 1.8 was released in December 2022, 1.8.0 was released on January 11, 2023.

Kotlin 1.9 was released in July 2023, 1.9.0 was released on July 6, 2023.

Kotlin 2.0 was released in May 2024, 2.0.0 was released on May 21, 2024.

Design

Development lead Andrey Breslav has said that Kotlin is designed to be an industrial-strength object-oriented language, and a "better language" than Java, but still be fully interoperable with Java code, allowing companies to make a gradual migration from Java to Kotlin.

Semicolons are optional as a statement terminator; in most cases a newline is sufficient for the compiler to deduce that the statement has ended.

Kotlin variable declarations and parameter lists have the data type come after the variable name (and with a colon separator), similar to Ada, BASIC, Pascal, TypeScript and Rust. This, according to an article from Roman Elizarov, current project lead, results in alignment of variable names and is more pleasing to eyes, especially when there are a few variable declarations in succession, and one or more of the types is too complex for type inference, or needs to be declared explicitly for human readers to understand.

Variables in Kotlin can be read-only, declared with the val keyword, or mutable, declared with the var keyword.

Class members are public by default, and classes themselves are final by default, meaning that creating a derived class is disabled unless the base class is declared with the open keyword.

In addition to the classes and member functions (which are equivalent to methods) of object-oriented programming, Kotlin also supports procedural programming with the use of functions. Kotlin functions and constructors support default arguments, variable-length argument lists, named arguments, and overloading by unique signature. Class member functions are virtual, i.e. dispatched based on the runtime type of the object they are called on.

Kotlin 1.3 added support for contracts, which are stable for the standard library declarations, but still experimental for user-defined declarations. Contracts are inspired by Eiffel's design by contract programming paradigm.

Kotlin code may be compiled to JavaScript, allowing for interoperability between code written in the two languages. This can be used either to write full web applications in Kotlin, or to share code between a Kotlin backend and a JavaScript frontend.

Syntax

Procedural programming style

Kotlin relaxes Java's restriction of allowing static methods and variables to exist only within a class body. Static objects and functions can be defined at the top level of the package without needing a redundant class level. For compatibility with Java, Kotlin provides a JvmName annotation which specifies a class name used when the package is viewed from a Java project. For example, @file:JvmName("JavaClassName").

Main entry point

As in C, C++, C#, Java, and Go, the entry point to a Kotlin program is a function named "main", which may be passed an array containing any command-line arguments. This is optional since Kotlin 1.3. Perl, PHP, and Unix shell–style string interpolation is supported. Type inference is also supported.

// Hello, World! example fun main() { val scope = "World" println("Hello, $scope!") } fun main(args: Array<String>) { for (arg in args) println(arg) }

Extension functions

Similar to C#, Kotlin allows adding an extension function to any class without the formalities of creating a derived class with new functions. An extension function has access to all the public interface of a class, which it can use to create a new function interface to a target class. An extension function will appear exactly like a function of the class and will be shown in code completion inspection of class functions. For example:

package MyStringExtensions fun String.lastChar(): Char = get(length - 1) >>> println("Kotlin".lastChar())

By placing the preceding code in the top-level of a package, the String class is extended to include a lastChar function that was not included in the original definition of the String class.

// Overloading '+' operator using an extension function operator fun Point.plus(other: Point): Point { return Point(x + other.x, y + other.y) } >>> val p1 = Point(10, 20) >>> val p2 = Point(30, 40) >>> println(p1 + p2) Point(x=40, y=60)

Unpack arguments with spread operator

Similar to Python, the spread operator asterisk (*) unpacks an array's contents as individual arguments to a function, e.g:

fun main(args: Array<String>) { val list = listOf("args: ", *args) println(list) }

Destructuring declarations

Destructuring declarations decompose an object into multiple variables at once, e.g. a 2D coordinate object might be destructured into two integers, x and y.

For example, the Map.Entry object supports destructuring to simplify access to its key and value fields:

for ((key, value) in map) println("$key: $value")

Nested functions

Kotlin allows local functions to be declared inside of other functions or methods.

class User(val id: Int, val name: String, val address: String) fun saveUserToDb(user: User) { fun validate(user: User, value: String, fieldName: String) { require(value.isNotEmpty()) { "Can't save user ${user.id}: empty $fieldName" } } validate(user, user.name, "Name") validate(user, user.address, "Address") // Save user to the database ... }

Classes are final by default

In Kotlin, to derive a new class from a base class type, the base class needs to be explicitly marked as "open". This is in contrast to most object-oriented languages such as Java where classes are open by default.

Example of a base class that is open to deriving a new subclass from it:

// open on the class means this class will allow derived classes open class MegaButton { // no-open on a function means that // polymorphic behavior disabled if function overridden in derived class fun disable() { ... } // open on a function means that // polymorphic behavior allowed if function is overridden in derived class open fun animate() { ... } } class GigaButton: MegaButton() { // Explicit use of override keyword required to override a function in derived class override fun animate() { println("Giga Click!") } }

Abstract classes are open by default

Abstract classes define abstract or "pure virtual" placeholder functions that will be defined in a derived class. Abstract classes are open by default.

// No need for the open keyword here, it’s already open by default abstract class Animated { // This virtual function is already open by default as well abstract fun animate() open fun stopAnimating() { } fun animateTwice() { } }

Classes are public by default

Kotlin provides the following keywords to restrict visibility for top-level declaration, such as classes, and for class members: public, internal, protected, and private.

When applied to a class member:

Keyword Visibility
public (default) Everywhere
internal Within a module
protected Within subclasses
private Within a class

When applied to a top-level declaration:

Keyword Visibility
public (default) Everywhere
internal Within a module
private Within a file

Example:

// Class is visible only to current module internal open class TalkativeButton { // method is only visible to current class private fun yell() = println("Hey!") // method is visible to current class and derived classes protected fun whisper() = println("Let's talk!") } internal class MyTalkativeButton: TalkativeButton() { fun utter() = super.whisper() } MyTalkativeButton().utter()

Primary constructor vs. secondary constructors

Kotlin supports the specification of a "primary constructor" as part of the class definition itself, consisting of an argument list following the class name. This argument list supports an expanded syntax on Kotlin's standard function argument lists that enables declaration of class properties in the primary constructor, including visibility, extensibility, and mutability attributes. Additionally, when defining a subclass, properties in super-interfaces and super-classes can be overridden in the primary constructor.

// Example of class using primary constructor syntax // (Only one constructor required for this class) open class BaseUser(open var isSubscribed: Boolean) open class PowerUser(protected val nickname: String, final override var isSubscribed: Boolean = true):BaseUser(isSubscribed) { }

However, in cases where more than one constructor is needed for a class, a more general constructor can be defined using secondary constructor syntax, which closely resembles the constructor syntax used in most object-oriented languages like C++, C#, and Java.

// Example of class using secondary constructor syntax // (more than one constructor required for this class) class Context class AttributeSet open class View(ctx:Context) { constructor(ctx: Context, attr: AttributeSet): this(ctx) } class MyButton : View { // Constructor #1 constructor(ctx: Context) : super(ctx) { } // Constructor #2 constructor(ctx: Context, attr: AttributeSet) : super(ctx, attr) { // ... } }

Sealed classes

Sealed classes and interfaces restrict subclass hierarchies, meaning more control over the inheritance hierarchy.

Declaration of sealed interface and class:

sealed interface Expr sealed class Job

All the subclasses of the sealed class are defined at compile time. No new subclasses can be added to it after the compilation of the module having the sealed class. For example, a sealed class in a compiled jar file cannot be subclassed.

sealed class Vehicle data class Car(val brandName: String, val owner: String, val color: String): Vehicle() class Bike(val brandName: String, val owner: String, val color: String): Vehicle() class Tractor(val brandName: String, val owner: String, val color: String): Vehicle() val kiaCar = Car("KIA", "John", "Blue") val hyundaiCar = Car("Hyundai", "Britto", "Green")

Data classes

Kotlin's data class construct defines classes whose primary purpose is storing data, similar Java's record types. This construct is similar to normal classes except that the key methods equals, hashCode and toString are automatically generated from the class properties.

Background

In Java, classes are expected to provide implementations for certain standard methods, so that they function properly with methods and classes provided by the standard library. Java's default implementation—which every class inherits from the base of the class hierarchy, Object—implements these methods only with regard to the identity of the object instance (usually its address in virtual memory). This is a problem, since it is extremely important to

(a) have information about the object's state in its String representation (toString) and

(b) detect whether two objects are similar (equals and hashCode). The latter two's implementations should also agree with each other, and therefore be implemented together—meaning when one is changed, the other should also be changed to match. Implementing this functionality also increases the efficiency of standard algorithms which rely on its correct behavior. Conversely, incorrect implementations can even cause errors.

Since implementing these methods manually or with external tools is cumbersome and often leads to repeated or boilerplate code, automatic generation of them as a language feature speeds up development and reduces the potential for errors.

Kotlin interactive shell

$ kotlinc-jvm type :help for help; :quit for quit >>> 2 + 2 4 >>> println("Hello, World!") Hello, World!

Kotlin as a scripting language

Kotlin can also be used as a scripting language. A script is a Kotlin source file using the .kts filename extension, with executable source code at the top-level scope:

// list_folders.kts import java.io.File val folders = File(args).listFiles { file -> file.isDirectory() } folders?.forEach(::println)

Scripts can be run by passing the -script option and the corresponding script file to the compiler.

$ kotlinc -script list_folders.kts "path_to_folder_to_inspect"

Null safety

Kotlin makes a distinction between nullable and non-nullable data types. All nullable objects must be declared with a "?" postfix after the type name. Operations on nullable objects need special care from developers: a null-check must be performed before using the value, either explicitly, or with the aid of Kotlin's null-safe operators:

// 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() fun sayHello(maybe: String?, neverNull: Int) { // use of Elvis operator val name: String = maybe ?: "stranger" println("Hello $name") }

Lambdas

Kotlin provides support for higher-order functions and anonymous functions, or lambdas.

// the following function takes a lambda, f, and executes f passing it the string "lambda" // note that (String) -> Unit indicates a lambda with a String parameter and Unit return type fun executeLambda(f: (String) -> Unit) { f("lambda") }

Lambdas are declared using braces, { }. If a lambda takes parameters, they are declared within the braces and followed by the -> operator.

// the following statement defines a lambda that takes a single parameter and passes it to the println function val l = { c : Any? -> println(c) } // lambdas with no parameters may simply be defined using { } val l2 = { print("no parameters") }

"Hello world" example

(Taken from and explained at https://kotlinlang.org/docs/kotlin-tour-hello-world.html.)

fun main() { println("Hello, world!") // Hello, world! }

Tools

Applications

When Kotlin was announced as an official Android development language at Google I/O in May 2017, it became the third language fully supported for Android, after Java and C++. As of 2020, Kotlin is the most widely used language on Android, with Google estimating that 70% of the top 1,000 apps on the Play Store are written in Kotlin. Google itself has 60 apps written in Kotlin, including Maps and Drive. Many Android apps, such as Google Home, are in the process of being migrated to Kotlin, and therefore use both Kotlin and Java. Kotlin on Android is seen as beneficial for its null-pointer safety, as well as for its features that make for shorter, more readable code.

In addition to its prominent use on Android, Kotlin is gaining traction in server-side development. The Spring Framework officially added Kotlin support with version 5, on 4 January 2017. To further support Kotlin, Spring has translated all its documentation to Kotlin, and added built-in support for many Kotlin-specific features such as coroutines. In addition to Spring, JetBrains has produced a Kotlin-first framework called Ktor for building web applications.

In 2020, JetBrains found in a survey of developers who use Kotlin that 56% were using Kotlin for mobile apps, while 47% were using it for a web back-end. Just over a third of all Kotlin developers said that they were migrating to Kotlin from another language. Most Kotlin users were targeting Android (or otherwise on the JVM), with only 6% using Kotlin Native.

Adoption

In 2018, Kotlin was the fastest growing language on GitHub, with 2.6 times more developers compared to 2017. It is the fourth most loved programming language according to the 2020 Stack Overflow Developer Survey.

Kotlin was also awarded the O'Reilly Open Source Software Conference Breakout Award for 2019.

Many companies / organizations have used Kotlin for backend development:

Some companies / organizations have used Kotlin for web development:

A number of companies have publicly stated they were using Kotlin:

See also

References

  1. ^ "Release Kotlin 2.0.0 (Repository)".
  2. ^ "What is the correct English pronunciation of Kotlin?". 16 October 2019. Archived from the original on 9 November 2019. Retrieved 9 November 2019.
  3. ^ "Kotlin for JavaScript - Kotlin Programming Language". Kotlin. Archived from the original on 16 August 2020. Retrieved 20 August 2020.
  4. ^ "Kotlin for cross-platform mobile development". JetBrains: Developer Tools for Professionals and Teams. Archived from the original on 19 August 2020. Retrieved 20 August 2020.
  5. ^ "Kotlin Foundation - Kotlin Programming Language". Kotlin. Archived from the original on 29 December 2019. Retrieved 16 December 2019.
  6. ^ a b Lardinois, Frederic (7 May 2019). "Kotlin is now Google's preferred language for Android app development". TechCrunch. Archived from the original on 7 May 2019. Retrieved 8 May 2019.
  7. ^ "Kotlin FAQ". Archived from the original on 2 June 2021. Retrieved 2 April 2023. Kotlin lets you choose the version of JVM for execution. By default, the Kotlin/JVM compiler produces Java 8 compatible bytecode. If you want to make use of optimizations available in newer versions of Java, you can explicitly specify the target Java version from 9 to 19. Note that in this case the resulting bytecode might not run on lower versions.
  8. ^ "Stability of Kotlin Components". Kotlin. 21 May 2021. Archived from the original on 29 July 2021. Retrieved 29 July 2021.
  9. ^ "Kotlin 1.5.0 – the First Big Release of 2021". Kotlin. 4 May 2021. Archived from the original on 12 August 2021. Retrieved 29 July 2021.
  10. ^ Mobius (8 January 2015), Андрей Бреслав — Kotlin для Android: коротко и ясно, archived from the original on 12 April 2023, retrieved 28 May 2017
  11. ^ Kieron Murphy (4 October 1996). "So why did they decide to call it Java?". JavaWorld. Archived from the original on 15 March 2019. Retrieved 14 October 2017.
  12. ^ Merriam-Webster (8 June 2023). "Java Definition & Meaning". www.merriam-webster.com. Archived from the original on 4 July 2023. Retrieved 3 July 2023.
  13. ^ a b Krill, Paul (22 July 2011). "JetBrains readies JVM language Kotlin". InfoWorld. Archived from the original on 7 September 2019. Retrieved 2 February 2014.
  14. ^ Waters, John (22 February 2012). "Kotlin Goes Open Source". ADTmag.com. 1105 Enterprise Computing Group. Archived from the original on 18 February 2014. Retrieved 2 February 2014.
  15. ^ "Why JetBrains needs Kotlin". 2 August 2011. Archived from the original on 16 August 2023. Retrieved 11 February 2018. we expect Kotlin to drive the sales of IntelliJ IDEA
  16. ^ "test · JetBrains/kotlin@3e4dce3". GitHub. Archived from the original on 17 October 2022. Retrieved 17 October 2022.
  17. ^ "Kotlin 1.0 Released: Pragmatic Language for JVM and Android | Kotlin Blog". Blog.jetbrains.com. 15 February 2016. Archived from the original on 24 January 2018. Retrieved 11 April 2017.
  18. ^ Shafirov, Maxim (17 May 2017). "Kotlin on Android. Now official". Archived from the original on 29 May 2023. Retrieved 18 May 2017. Today, at the Google I/O keynote, the Android team announced first-class support for Kotlin.
  19. ^ "Kotlin 1.2 Released: Sharing Code between Platforms | Kotlin Blog". blog.jetbrains.com. 28 November 2017. Archived from the original on 24 May 2023. Retrieved 29 November 2017.
  20. ^ "Multiplatform Projects - Kotlin Programming Language". Kotlin. Archived from the original on 18 August 2020. Retrieved 20 August 2020. Working on all platforms is an explicit goal for Kotlin, but we see it as a premise to a much more important goal: sharing code between platforms. With support for JVM, Android, JavaScript, iOS, Linux, Windows, Mac and even embedded systems like STM32, Kotlin can handle any and all components of a modern application.
  21. ^ "Kotlin/kotlin-full-stack-application-demo". Kotlin. 3 April 2020. Archived from the original on 14 September 2020. Retrieved 4 April 2020.
  22. ^ "Kotlin full stack app demo: update all involving versions to work with 1.3.70 release". youtrack.jetbrains.com. Archived from the original on 2 August 2020. Retrieved 4 April 2020.
  23. ^ "Kotlin 1.1 Released with JavaScript Support, Coroutines and more". Archived from the original on 4 June 2023. Retrieved 1 May 2017.
  24. ^ "What's New in Kotlin 1.4 - Kotlin Programming Language". Kotlin. Archived from the original on 8 June 2023. Retrieved 20 August 2020. In 1.4.0, we slightly change the Swift API generated from Kotlin with respect to the way exceptions are translated.
  25. ^ "What's new in Kotlin 1.7.0 | Kotlin". Kotlin Help. Archived from the original on 20 June 2022. Retrieved 20 June 2022.
  26. ^ Paul Krill (12 January 2023). "Kotlin 1.8.0 adds recursive copy, delete for directories". Archived from the original on 8 July 2023. Retrieved 8 March 2022.
  27. ^ Sarah Haggarty (6 July 2023). "Kotlin 1.9.0 Released". Archived from the original on 28 July 2023. Retrieved 6 July 2023.
  28. ^ Github (21 May 2024). "Kotlin 2.0.0". Archived from the original on 21 May 2024. Retrieved 21 May 2024.
  29. ^ "JVM Languages Report extended interview with Kotlin creator Andrey Breslav". Zeroturnaround.com. 22 April 2013. Archived from the original on 15 January 2019. Retrieved 2 February 2014.
  30. ^ "Semicolons". jetbrains.com. Archived from the original on 23 December 2015. Retrieved 8 February 2014.
  31. ^ "Types are moving to the right". Medium. 16 July 2020. Archived from the original on 22 May 2023. Retrieved 6 November 2021.
  32. ^ "Roman Elizarov is the new Project Lead for Kotlin". The Kotlin Blog. JetBrains. 19 November 2020. Archived from the original on 20 January 2022. Retrieved 7 November 2021.
  33. ^ "Basic Syntax". Kotlin. Jetbrains. Archived from the original on 29 January 2021. Retrieved 19 January 2018.
  34. ^ "functions". jetbrains.com. Archived from the original on 23 November 2015. Retrieved 8 February 2014.
  35. ^ "What's New in Kotlin 1.3 - Kotlin Programming Language". Kotlin. Archived from the original on 22 August 2023. Retrieved 4 April 2020.
  36. ^ "Design by Contract (DbC) design considerations". Kotlin Discussions. 16 August 2012. Archived from the original on 5 April 2023. Retrieved 4 April 2020. Implement the full semantics of Eiffel DbC and improve upon it.
  37. ^ "Kotlin for JavaScript | Kotlin". Kotlin Help. 21 January 2021. Archived from the original on 14 July 2023. Retrieved 19 March 2021.
  38. ^ "Kotlin Examples: Learn Kotlin Programming By Example". Archived from the original on 18 November 2021. Retrieved 13 April 2019.
  39. ^ a b Eric, Martin, ed. (8 January 2024). "Java equals() and hashCode() Contracts". Baeldung. Archived from the original on 19 November 2023. Retrieved 8 April 2024. By default, the Object class defines both the .equals() and .hashCode() methods. As a result, every Java class implicitly has these two methods. The default implementation of equals() in the Object class compares the identity of the object. The second criterion of the .hashCode() contract has an important consequence: If we override equals(), we must also override hashCode(). We would expect myTeamLeader to return "Anne," but with the current code, it doesn't. If we want to use instances of the Team class as HashMap keys, we have to override the hashCode() method so that it adheres to the contract; equal objects return the same hashCode.
  40. ^ "Object (Java Platform SE 8 )". docs.oracle.com. Archived from the original on 7 April 2024. Retrieved 8 April 2024. As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java™ programming language.)
  41. ^ "HashMap (Java Platform SE 8 )". docs.oracle.com. Archived from the original on 8 April 2024. Retrieved 8 April 2024. This implementation provides constant-time performance for the basic operations (get and put), assuming the hash function disperses the elements properly among the buckets.
  42. ^ "Higher-Order Functions and Lambdas". Kotlin. Jetbrains. Archived from the original on 22 January 2021. Retrieved 19 January 2018.
  43. ^ "Kotlin and Android". Android Developers. Archived from the original on 4 October 2023. Retrieved 19 June 2017.
  44. ^ "Using Maven – Kotlin Programming Language". kotlinlang.org. Archived from the original on 3 November 2016. Retrieved 9 May 2017.
  45. ^ "Using Ant – Kotlin Programming Language". kotlinlang.org. Archived from the original on 3 November 2016. Retrieved 9 May 2017.
  46. ^ "Using Gradle – Kotlin Programming Language". kotlinlang.org. Archived from the original on 9 November 2016. Retrieved 9 May 2017.
  47. ^ "Getting Started with Eclipse Neon – Kotlin Programming Language". Kotlinlang.org. 10 November 2016. Archived from the original on 18 May 2023. Retrieved 11 April 2017.
  48. ^ "JetBrains/kotlin-eclipse: Kotlin Plugin for Eclipse". GitHub. Archived from the original on 16 February 2016. Retrieved 11 April 2017.
  49. ^ "Kotlin :: JetBrains Plugin Repository". Plugins.jetbrains.com. 31 March 2017. Archived from the original on 25 June 2023. Retrieved 11 April 2017.
  50. ^ "What's New in IntelliJ IDEA 2017.1". Jetbrains.com. Archived from the original on 3 October 2023. Retrieved 11 April 2017.
  51. ^ "Gradle | Kotlin". Kotlin Help. Archived from the original on 8 April 2024. Retrieved 8 April 2024.
  52. ^ Lardinois, Frederic (17 May 2017). "Google makes Kotlin a first-class language for writing Android apps". techcrunch.com. Archived from the original on 22 May 2017. Retrieved 28 June 2018.
  53. ^ "Kotlin programming language: How Google is using it to squash the code bugs that cause most crashes". ZDNet. Archived from the original on 6 April 2023. Retrieved 6 December 2020.
  54. ^ "Introducing Kotlin support in Spring Framework 5.0". Spring. Pivotal. 4 January 2017. Archived from the original on 23 August 2023. Retrieved 29 September 2020.
  55. ^ "The State of Kotlin Support in Spring". JetBrains. 14 August 2020. Archived from the original on 7 June 2023. Retrieved 6 December 2020.
  56. ^ "Review of Microservices Frameworks: A Look at Spring Boot Alternatives". DZone. Archived from the original on 21 May 2023. Retrieved 6 December 2020.
  57. ^ "Kotlin Programming - The State of Developer Ecosystem 2020". JetBrains. Archived from the original on 5 April 2023. Retrieved 29 September 2020.
  58. ^ "The state of the Octoverse". Archived from the original on 22 March 2019. Retrieved 24 July 2019.
  59. ^ "Stack Overflow Developer Survey 2020". Archived from the original on 4 June 2020. Retrieved 28 May 2020.
  60. ^ "Kotlin wins Breakout Project of the Year award at OSCON '19". 18 July 2019. Archived from the original on 17 May 2022. Retrieved 24 July 2019.
  61. ^ "Kotlin at Allegro". Talking Kotlin. October 2018. Archived from the original on 1 June 2023. Retrieved 29 September 2020.
  62. ^ "QLDB at Amazon". Talking Kotlin. 30 June 2020. Archived from the original on 1 June 2023. Retrieved 29 September 2020.
  63. ^ "Future of Jira Software powered by Kotlin". YouTube. Archived from the original on 1 September 2023. Retrieved 1 September 2023.
  64. ^ "Going Full Kotlin Multiplatform". Talking Kotlin. 14 April 2020. Archived from the original on 5 April 2023. Retrieved 29 September 2020.
  65. ^ "square/sqldelight". GitHub. Archived from the original on 20 June 2019. Retrieved 24 July 2019.
  66. ^ "Using Kotlin for backend development at Flux". Talking Kotlin. 14 August 2019. Archived from the original on 1 June 2023. Retrieved 29 September 2020.
  67. ^ "State of Kotlin on Android". YouTube. Archived from the original on 15 January 2023. Retrieved 29 September 2020.
  68. ^ "Gradle Kotlin DSL Primer". docs.gradle.org. Archived from the original on 18 August 2023. Retrieved 29 September 2020.
  69. ^ "Kotless". Talking Kotlin. 30 January 2020. Archived from the original on 5 April 2023. Retrieved 29 September 2020.
  70. ^ "Kotlin on the backend at Meshcloud". Talking Kotlin. 28 February 2018. Archived from the original on 6 April 2023. Retrieved 29 September 2020.
  71. ^ "KotlinConf 2019: Kotlin Runs Taxes in Norway by Jarle Hansen & Anders Mikkelsen". YouTube. Archived from the original on 10 April 2023. Retrieved 29 September 2020.
  72. ^ "Greenfield Kotlin at OLX". Talking Kotlin. 24 August 2018. Archived from the original on 1 June 2023. Retrieved 29 September 2020.
  73. ^ "Application Monitoring with Micrometer". Talking Kotlin. 14 June 2018. Archived from the original on 1 April 2023. Retrieved 29 September 2020.
  74. ^ "Groovy and Kotlin Interop at Rocket Travel". Talking Kotlin. 14 May 2018. Archived from the original on 5 April 2023. Retrieved 29 September 2020.
  75. ^ "Kotlin at Shazam". Talking Kotlin. 29 July 2018. Archived from the original on 1 April 2023. Retrieved 29 September 2020.
  76. ^ "Zally - An API Linter". Talking Kotlin. 29 January 2018. Archived from the original on 6 April 2023. Retrieved 29 September 2020.
  77. ^ "Java/Kotlin Developer - Barclays - Prague - Wizbii". Wizbii.com. Retrieved 29 September 2020.
  78. ^ "KotlinConf 2017 - Frontend Kotlin from the Trenches by Gaetan Zoritchak". YouTube. Archived from the original on 10 April 2023. Retrieved 29 September 2020.
  79. ^ "Fritz2". Talking Kotlin. 14 September 2020. Archived from the original on 6 April 2023. Retrieved 29 September 2020.
  80. ^ "KotlinConf 2019: Kotlin in Space by Maxim Mazin". YouTube. Archived from the original on 9 April 2023. Retrieved 29 September 2020.
  81. ^ "How we made Basecamp 3's Android app 100% Kotlin – Signal v. Noise". Signal v. Noise. 29 April 2017. Archived from the original on 1 August 2018. Retrieved 1 May 2017.
  82. ^ "Becoming bilingual@coursera". 26 April 2018. Archived from the original on 15 January 2023. Retrieved 24 July 2019.
  83. ^ "Kotlin in Production – What works, Whats broken". Blog.dripstat.com. 24 September 2016. Archived from the original on 1 July 2019. Retrieved 11 April 2017.
  84. ^ "Duolingo on Twitter". Archived from the original on 16 March 2023. Retrieved 13 April 2020.
  85. ^ "Rob Spieldenner on twitter". Archived from the original on 25 December 2022. Retrieved 24 July 2019.
  86. ^ "Droidcon NYC 2016 - Kotlin in Production". YouTube. Archived from the original on 14 April 2023. Retrieved 24 July 2019.
  87. ^ "Dan Lew on Twitter". Archived from the original on 2 May 2023. Retrieved 24 July 2019.
  88. ^ "Measuring Kotlin Build Performance at Uber". 30 April 2019. Archived from the original on 5 June 2023. Retrieved 6 March 2024.

External links