Kotlin 1.9.0 Released

Sarah Haggarty

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The Kotlin 1.9.0 release is out and the K2 compiler for the JVM is now in Beta. This release contains new language features as well as improvements for Kotlin Multiplatform and Kotlin/Native.

Here are some highlights from this release:

• New Kotlin K2 compiler updates
• Stable replacement of the enum class values function
• Stable ..< operator for open-ended ranges
• New common function to get regex capture group by name
• New path utility to create parent directories
• Preview of the Gradle configuration cache in Kotlin Multiplatform
• Changes for Android target support in Kotlin Multiplatform
• Preview of custom memory allocator in Kotlin/Native
• Library linkage in Kotlin/Native
• Size-related optimizations in Kotlin/Wasm

For the complete list of changes, refer to What’s new in Kotlin 1.9.0 or the release notes on GitHub.

New Kotlin K2 compiler is Beta for JVM

The Kotlin team at JetBrains is continuing to stabilize the new K2 compiler and we are excited to announce that the new Kotlin K2 compiler for JVM has now achieved its Beta milestone on our journey towards the Kotlin 2.0 release. The compiler has been thoroughly tested by successfully compiling an extensive range of projects that the Kotlin team utilizes for quality assurance.

The K2 compiler aims to bring major performance improvements, speed up new language feature development, unify all platforms that Kotlin supports, and provide a better architecture for multiplatform projects. 

We’re making great strides in facilitating compatibility with other popular compiler plugins. Support for Kotlin Symbol Processing (KSP) and Jetpack Compose is on the horizon, with plans to integrate K2 support soon. We invite you to test out K2 on your Kotlin/JVM projects and share your valuable feedback in our issue tracker. Your inputs will help us to refine K2 before it becomes the default stable compiler in Kotlin 2.0.

Our ambition doesn’t stop there. We strive to achieve the same high level of quality for multiplatform support with the K2 compiler. This commitment is in tandem with our ongoing efforts on Kotlin Multiplatform stabilization. Our target is to achieve full beta-quality support for multiplatform projects in K2 concurrently with the stable release of Kotlin Multiplatform.

We eagerly await your feedback as we move forward on this exciting development journey. Together, we can shape the future of Kotlin 2.0.

For more information about how to enable the K2 compiler, see Try the K2 compiler in your project.

How to install Kotlin 1.9.0

If you already use IntelliJ IDEA 2022.3.3, 2023.1.1, the IDE will suggest updating Kotlin to 1.9.0 automatically. You can also update manually by following these instructions. IntelliJ IDEA 2023.2 will include the Kotlin 1.9.0 plugin.

For Android Studio Giraffe (223) and Hedgehog (231), the Kotlin 1.9.0 plugin will be included in upcoming Android Studios updates. If you need the command-line compiler, download it from the GitHub release page.

If you run into any problems

• Find help on Slack (get an invite).

• Report issues to our issue tracker, YouTrack.

Top issue reporters from YouTrack

Jinseong Jeon (38 issues), Carlos Ballesteros Velasco (27 issues), Adam (24 issues), Martin Bonnin (15 issues), Zac Sweers (15 issues), Andreas Malik (15 issues), Gleb Minaev (15 issues), Waldemar Kornewald (13 issues), AndroidDeveloperLB (13 issues), Philip Wedemann (12 issues), Mads Ager (12 issues), Oleg Yukhnevich (12 issues), Revin Cao (11 issues), Matthew Groth (11 issues), Andy Magee (11 issues), Sébastien Deleuze (11 issues), Steven Schäfer (10 issues), Robert Stoll (10 issues), Björn Kautler (10 issues), Thodoris Sotiropoulos (9 issues)

External contributors

We’d like to thank all of our contributors whose pull requests were included in this release: pyos, Jinseong Jeon, Mads Ager, Justin Paupore, Steven Schäfer, Troels Bjerre Lund, Jaebaek Seo, hungvietnguyen, Nicklas Ansman Giertz, Kevin Bourrillion, mcpiroman, Xin Wang, Johan Bay, Oleg Yukhnevich, Mark Mann, wrongwrong, Martin Bonnin, xiaozihan.larryxiao, Kristoffer Andersen, Jerome Prinet, AngryGami, akerimsenol, deotime, mcpiroman, Mark Mann, Martin Petrov, Mads Sig Ager, Nelson Osacky, Nicklas Ansman, Loïc Mangeonjean, Oleg Bask, OliverO2, Jérôme Prinet, Paŭlo Ebermann, Polina Mitrikovskaia, Jiaxiang Chen, Jake Wharton, Shahlin Ibrahim, Daniel Santiago, Clark Perkins, Takumi Maeomote, Thomas Tresansky, Ting-Yuan Huang.

Special thanks to our EAP Champions 🥇👏

• Zac Sweers
• Alexander Nozik
• Oleg Yukhnevich
• Simon Marquis
• Josh Friend
• Benoit ‘BoD’ Lubek
• Yang

What else to read and watch

• What’s new in Kotlin 1.9.0 documentation
• What’s new in Kotlin 1.9.0 on YouTube
• The K2 Compiler Is Going Stable in Kotlin 2.0
• Kotlin EAP Champions

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