Kotlin (programming language) facts for kids
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| Paradigm | Multi-paradigm: object-oriented, functional, imperative, block structured, declarative, generic, reflective, concurrent |
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| Designed by | JetBrains |
| Developer | JetBrains |
| First appeared | July 22, 2011 |
| Stable release |
1.9.0
 / 6 July 2023 |
| Typing discipline | Inferred, static, strong |
| Platform |
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| OS | Cross-platform |
| License | Apache License 2.0 |
| Filename extensions | .kt, .kts |
| Influenced by | |
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Kotlin is a modern programming language that helps people create computer programs and apps. It's a "general-purpose" language, meaning you can use it for many different types of projects. Kotlin is also "cross-platform," which means programs written in Kotlin can run on various devices, like Android phones, iPhones, and computers with Windows, macOS, or Linux.
One cool thing about Kotlin is that it works really well with Java, another very popular programming language. This makes it easy for developers to use parts of Java in their Kotlin projects. Kotlin is designed to be clear and easy to read, which helps programmers write code faster and with fewer mistakes. The company JetBrains created Kotlin and continues to develop it.
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What is Kotlin Used For?
Kotlin is super popular for building apps, especially for Android phones. In fact, on May 7, 2019, Google announced that Kotlin is now their favorite language for Android app developers! This means many new Android apps are being made with Kotlin.
Since October 2017, Kotlin has been included in Android Studio, which is a special tool developers use to build Android apps. This makes it simple for them to choose Kotlin instead of Java.
Kotlin for Different Platforms
Kotlin isn't just for Android! It can also be used for:
- Web applications: Kotlin/JS lets developers build parts of websites that run in your web browser. This is great for interactive web pages.
- Native applications: Kotlin/Native allows programmers to create apps that run directly on your computer or phone, without needing a special program like Java Virtual Machine (JVM). This is how they can make apps for iPhones (iOS) that share code with Android apps.
Example Code
Let's look at a simple example of a "Hello World!" program written in Kotlin. This is often the first program people learn to write in a new language.
// Hello World Program
fun main(args : Array<String>) {
println("Hello world!")
}This small piece of code tells the computer to display the words "Hello world!" on the screen.
Who Uses Kotlin?
Kotlin is becoming more and more popular! In 2018, it was the fastest-growing programming language on GitHub, a website where developers share their code. It had 2.6 times more developers using it compared to 2017.
Many big companies and organizations use Kotlin for different parts of their software:
Companies Using Kotlin for Backend Development
"Backend development" means building the parts of a website or app that you don't see, like servers and databases.
- Allegro
- Amazon
- Cash App
- Flux
- Gradle
- JetBrains
- Meshcloud
- Norwegian Tax Administration
- OLX
- Pivotal
- Rocket Travel
- Shazam
- Zalando
Companies Using Kotlin for Web Development
These companies use Kotlin to build parts of websites that run in your browser.
- Barclay's Bank
- Data2viz
- Fritz2
- JetBrains
Other Companies Using Kotlin
Many other well-known companies also use Kotlin for their projects:
- Basecamp
- Corda (a special system used by banks like Goldman Sachs and J.P. Morgan)
- Coursera
- DripStat
- Duolingo
- Netflix
- Trello
- Uber
