| [](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub) |
| [](https://teamcity.jetbrains.com/buildConfiguration/Kotlin_KotlinPublic_Compiler?branch=%3Cdefault%3E&buildTypeTab=overview&mode=builds) |
| [](https://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.jetbrains.kotlin%22) |
| [](https://www.apache.org/licenses/LICENSE-2.0) |
| [](https://ge.jetbrains.com/scans?search.rootProjectNames=Kotlin) |
| |
| # Kotlin Programming Language |
| |
| Welcome to [Kotlin](https://kotlinlang.org/)! |
| It is an open-source, statically typed programming language supported and developed by [JetBrains](https://www.jetbrains.com/) and open-source contributors. |
| |
| Some handy links: |
| |
| * [Kotlin Site](https://kotlinlang.org/) |
| * [Getting Started Guide](https://kotlinlang.org/docs/tutorials/getting-started.html) |
| * [Try Kotlin](https://play.kotlinlang.org/) |
| * [Kotlin Standard Library](https://kotlinlang.org/api/latest/jvm/stdlib/index.html) |
| * [Issue Tracker](https://youtrack.jetbrains.com/issues/KT) |
| * [Kotlin YouTube Channel](https://www.youtube.com/channel/UCP7uiEZIqci43m22KDl0sNw) |
| * [Forum](https://discuss.kotlinlang.org/) |
| * [Kotlin Blog](https://blog.jetbrains.com/kotlin/) |
| * [Subscribe to Kotlin YouTube channel](https://www.youtube.com/channel/UCP7uiEZIqci43m22KDl0sNw) |
| * [Follow Kotlin on Twitter](https://twitter.com/kotlin) |
| * [Public Slack channel](https://slack.kotlinlang.org/) |
| * [TeamCity CI build](https://teamcity.jetbrains.com/project.html?tab=projectOverview&projectId=Kotlin) |
| |
| ## Kotlin Multiplatform capabilities |
| |
| Support for multiplatform programming is one of Kotlin’s key benefits. It reduces time spent writing and maintaining the same code for [different platforms](https://kotlinlang.org/docs/reference/mpp-supported-platforms.html) while retaining the flexibility and benefits of native programming. |
| |
| * [Kotlin Multiplatform Mobile](https://kotlinlang.org/lp/mobile/) for sharing code between Android and iOS |
| * [Getting Started with Kotlin Multiplatform Mobile Guide](https://kotlinlang.org/docs/mobile/create-first-app.html) |
| * [Kotlin Multiplatform Benefits](https://kotlinlang.org/docs/reference/multiplatform.html) |
| * [Share code on all platforms](https://kotlinlang.org/docs/reference/mpp-share-on-platforms.html#share-code-on-all-platforms) |
| * [Share code on similar platforms](https://kotlinlang.org/docs/reference/mpp-share-on-platforms.html#share-code-on-similar-platforms) |
| |
| ## Editing Kotlin |
| |
| * [Kotlin IntelliJ IDEA Plugin](https://kotlinlang.org/docs/tutorials/getting-started.html) ([source code](https://github.com/JetBrains/intellij-community/tree/master/plugins/kotlin)) |
| * [Kotlin Eclipse Plugin](https://kotlinlang.org/docs/tutorials/getting-started-eclipse.html) |
| * [Kotlin Sublime Text Package](https://github.com/vkostyukov/kotlin-sublime-package) |
| |
| ## Build environment requirements |
| |
| This repository is using [Gradle toolchains](https://docs.gradle.org/current/userguide/toolchains.html) feature |
| to select and auto-provision required JDKs from [AdoptOpenJdk](https://adoptopenjdk.net) project. |
| |
| Alternatively, it is still possible to only provide required JDKs via environment variables |
| (see [gradle.properties](./gradle.properties#L5) for supported variable names). To ensure Gradle uses only JDKs |
| from environmental variables - disable Gradle toolchain auto-detection by passing `-Porg.gradle.java.installations.auto-detect=false` option |
| (or put it into `$GRADLE_USER_HOME/gradle.properties`). |
| |
| On Windows you might need to add long paths setting to the repo: |
| |
| git config core.longpaths true |
| |
| ## Building |
| |
| The project is built with Gradle. Run Gradle to build the project and to run the tests |
| using the following command on Unix/macOS: |
| |
| ./gradlew <tasks-and-options> |
| |
| or the following command on Windows: |
| |
| gradlew <tasks-and-options> |
| |
| On the first project configuration gradle will download and setup the dependencies on |
| |
| * `intellij-core` is a part of command line compiler and contains only necessary APIs. |
| * `idea-full` is a full blown IntelliJ IDEA Community Edition to be used in the plugin module. |
| |
| These dependencies are quite large, so depending on the quality of your internet connection |
| you might face timeouts getting them. In this case, you can increase timeout by specifying the following |
| command line parameters on the first run: |
| |
| ./gradlew -Dhttp.socketTimeout=60000 -Dhttp.connectionTimeout=60000 |
| |
| ## Important gradle tasks |
| |
| - `clean` - clean build results |
| - `dist` - assembles the compiler distribution into `dist/kotlinc/` folder |
| - `install` - build and install all public artifacts into local maven repository |
| - `coreLibsTest` - build and run stdlib, reflect and kotlin-test tests |
| - `gradlePluginTest` - build and run gradle plugin tests |
| - `compilerTest` - build and run all compiler tests |
| |
| To reproduce TeamCity build use `-Pteamcity=true` flag. Local builds don't run proguard and have jar compression disabled by default. |
| |
| **OPTIONAL:** Some artifacts, mainly Maven plugin ones, are built separately with Maven. |
| Refer to [libraries/ReadMe.md](libraries/ReadMe.md) for details. |
| |
| To build Kotlin/Native, see |
| [kotlin-native/README.md](kotlin-native/README.md#building-from-source). |
| |
| ## <a name="working-in-idea"></a> Working with the project in IntelliJ IDEA |
| |
| It is recommended to use the latest released version of Intellij IDEA (Community or Ultimate Edition). You can download IntelliJ IDEA [here](https://www.jetbrains.com/idea/download). |
| |
| After cloning the project, import the project in IntelliJ by choosing the project directory in the Open project dialog. |
| |
| For handy work with compiler tests it's recommended to use [ |
| Kotlin Compiler Test Helper](https://github.com/demiurg906/test-data-helper-plugin) |
| |
| ### Dependency verification |
| |
| We have a [dependencies verification](https://docs.gradle.org/current/userguide/dependency_verification.html) feature enabled in the |
| repository for all Gradle builds. Gradle will check hashes (md5 and sha256) of used dependencies and will fail builds with |
| `Dependency verification failed` errors when local artifacts are absent or have different hashes listed in the |
| [verification-metadata.xml](https://github.com/JetBrains/kotlin/blob/master/gradle/verification-metadata.xml) file. |
| |
| It's expected that `verification-metadata.xml` should only be updated with the commits that modify the build. There are some tips how |
| to perform such updates: |
| |
| - Delete `components` section of `verification-metadata.xml` to avoid stockpiling of old unused dependencies. You may use the following command: |
| ```bash |
| #macOS |
| sed -i '' -e '/<components>/,/<\/components>/d' gradle/verification-metadata.xml |
| #Linux & Git for Windows |
| sed -i -e '/<components>/,/<\/components>/d' gradle/verification-metadata.xml |
| ``` |
| - Re-generate dependencies with Gradle's `--write-verification-metadata` command (verify update relates to your changes) |
| |
| ```bash |
| ./gradlew -i --write-verification-metadata sha256,md5 -Pkotlin.native.enabled=true resolveDependencies |
| ``` |
| |
| *`resolveDependencies` task resolves dependencies for all platforms including dependencies downloaded by plugins.* |
| |
| Keep in mind: |
| |
| - If you’re adding a dependency with OS mentioned in an artifact name (`darwin`, `mac`, `osx`, `linux`, `windows`), remember to add them to |
| `implicitDependencies` configuration or update `resolveDependencies` task if needed. `resolveDependencies` should resolve all dependencies |
| including dependencies for different platforms. |
| - If you have a `local.properties` file in your Kotlin project folder, make sure that it doesn't contain `kotlin.native.enabled=false`. |
| Otherwise, native-only dependencies may not be added to the verification metadata. This is because `local.properties` has higher |
| precedence than the `-Pkotlin.native.enabled=true` specified in the Gradle command. |
| |
| ## Using -dev versions |
| |
| We publish `-dev` versions frequently. |
| |
| For `-dev` versions you can use the [list of available versions](https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap/org/jetbrains/kotlin/kotlin-compiler/maven-metadata.xml) and include this maven repository: |
| |
| ```kotlin |
| maven("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap") |
| ``` |
| |
| # License |
| Kotlin is distributed under the terms of the Apache License (Version 2.0). See [license folder](license/README.md) for details. |
| |
| # Contributing |
| |
| Please be sure to review Kotlin's [contributing guidelines](docs/contributing.md) to learn how to help the project. |
