Kotlin (programming language)

Kotlin (programming language)
Name	Kotlin
Paradigm	Multi-paradigm: object-oriented, functional, imperative, declarative
Designer	JetBrains
Developer	JetBrains and open-source contributors
Latest release version	2.0.0
Latest release date	22 May 2024
Typing	Static, inferred, null-safe
Influenced by	Java, Scala, Groovy, C#, JavaScript
Influenced	Swift
Operating system	Cross-platform
License	Apache License 2.0
Website	kotlinlang.org

Kotlin (programming language) is a cross-platform, statically typed, general-purpose programming language with type inference, designed and developed by the software company JetBrains. It is designed to interoperate fully with Java, and its JVM version is compiled to Java bytecode. Kotlin is widely used for Android development, server-side applications, and increasingly for web and desktop development.

History

The project to develop Kotlin was initiated by JetBrains in 2010, with the goal of creating a more modern and concise language for its IntelliJ IDEA-based IDEs that could also address common Java shortcomings. The language was officially unveiled in 2011 and named after Kotlin Island near St. Petersburg. The first stable version, Kotlin 1.0, was released in February 2016. A major milestone in its adoption came in 2017 when Google announced official support for Kotlin on the Android platform at Google I/O. In 2019, Google further declared Kotlin its preferred language for Android app development. The language continues to evolve under the stewardship of the Kotlin Foundation, established in 2018 by JetBrains and Google.

Features

Kotlin introduces several features aimed at improving developer productivity and code safety. A core feature is null safety, designed to eliminate the danger of null pointer exceptions common in Java. It supports both object-oriented and functional programming paradigms, featuring lambda expressions, higher-order functions, and extension functions. Other notable features include coroutines for asynchronous programming, data classes for modeling immutable data, smart casts, and sealed classes. Its type inference system reduces boilerplate code while maintaining static typing guarantees.

Syntax

Kotlin's syntax is designed to be concise and expressive, reducing the amount of boilerplate code required compared to Java. Semicolons are optional, and the type declaration follows the variable name (e.g., `val name: String`). Control flow structures like if and when can be used as expressions that return a value. Function declarations use the `fun` keyword, and default and named arguments are supported. The language also provides concise syntax for creating data classes, singleton objects using the `object` keyword, and string interpolation.

Development tools

The primary IDE for Kotlin development is JetBrains' IntelliJ IDEA, which offers excellent support including code completion, refactoring, and debugging. The Kotlin plugin is also available for other IDEs like Android Studio and Eclipse. The build tools most commonly used are Gradle and Maven, both of which have first-class Kotlin support. The official compiler, `kotlinc`, can produce JVM bytecode, JavaScript, or native binaries via Kotlin/Native. The Kotlin Playground is an online tool for quickly testing code snippets.

Adoption

Kotlin has seen rapid and widespread adoption, particularly in Android development following Google's endorsement. Major companies like Google, Netflix, Uber, X (formerly Twitter), Pinterest, and Trello use Kotlin in their production applications. Beyond mobile, it is used for backend services with frameworks like Ktor and Spring, and for web frontends with Kotlin/JS. JetBrains itself uses Kotlin extensively in products like IntelliJ IDEA and Space. Its adoption is also growing in areas like data science and multiplatform mobile development with Kotlin Multiplatform.

Reception

Kotlin has been received very positively by the developer community. It consistently ranks highly in surveys like the Stack Overflow Developer Survey and the RedMonk Programming Language Rankings. Reviewers and developers often praise its pragmatic design, seamless Java interoperability, and concise syntax that addresses Java's verbosity. The backing by both JetBrains and Google has provided significant credibility and ensured robust tooling and continued evolution. Criticisms have occasionally focused on compilation speed in large projects or the learning curve associated with its functional features, but these are generally considered minor compared to its benefits.

Category:Programming languages Category:JVM programming languages Category:Android software development