IntelliJ IDEA 2022.2 Help

Get started with Kotlin

Before you start working with Kotlin, make sure that the plugin is enabled. The plugin is bundled with IntelliJ IDEA and is activated by default. If the plugin is not activated, enable it on the Plugins page of the IDE settings Ctrl+Alt+S as described in Install plugins.

IntelliJ IDEA provides first-class support for Kotlin. It includes Kotlin-specific project templates, coding assistance, refactorings, debugging, analysis tools, and so on. Most of the Java tools are available for Kotlin, so, for example, if you know how to use Java debugger or refactorings, your experience will be enough to use these in Kotlin. In this topic, you will find the instructions to get started with Kotlin in IntelliJ IDEA.

Create a Kotlin project without frameworks

This is a general-purpose project without specific frameworks. You will be able to add the necessary frameworks and technologies later at any time.

  1. On the Welcome screen, click New Project. Otherwise, from the main menu, select File | New | Project.

  2. From the list on the left, select New Project.

  3. Name the new project and change its location if necessary.

  4. Select the Create Git repository checkbox to place the new project under version control.

    You will be able to do it later at any time.

  5. From the Language list, select Kotlin.

    Creating a new project
  6. Select the IntelliJ build system. It's a native builder that doesn't require downloading additional artifacts.

    If you want to create a more complex project that needs further configuration, select Maven or Gradle. For Gradle, choose a language for the build script: Groovy or Kotlin.

  7. From the JDK list, select the JDK that you want to use in your project.

    If the JDK is installed on your computer, but not defined in the IDE, select Add JDK and specify the path to the JDK home directory.

    If you don't have the necessary JDK on your computer, select Download JDK.

  8. Enable the Add sample code option to create a file with a sample Hello World! application.

  9. Click Create.

Create a Kotlin Multiplatform project

  1. On the Welcome screen, click New Project. Otherwise, from the main menu, select File | New | Project.

  2. In the left-hand menu, select Kotlin Multiplatform.

  3. Select the project template. The template defines the project structure and dependencies. The following project templates are available:

    JVM

    • Console Application: console application with Kotlin/JVM. Use it for prototyping or testing purposes.

    Multiplatform

    • Library: library for sharing common code among different platforms.

    • Native Application: application with Kotlin/Native that works as a standalone application under a specific platform.

    • Full-Stack Web Application: full-functional web application using Kotlin/JS for the frontend and Kotlin/JVM for the backend.

    Kotlin/JS

    • Browser Application: frontend application with Kotlin/JS and non-Kotlin backend for browser. If you use Kotlin for backend, the better option is Full-Stack Web Application.

    • React Application: frontend application with Kotlin/JS and React UI framework for browser.

    • Node.JS Application: a standalone application with Kotlin/JS for the Node.js runtime.

    Compose Multiplatform (Old version)

    • Compose Desktop Application: a compose application targeting the desktop JVM platform (Windows, Linux, macOS).

    • Compose Multiplatform Application: Multiplatform (JVM/Windows, JVM/Linux, JVM/macOS, Android) Compose project with shared code in common modules.

    • Compose Web Application: a web Compose project for JS.

  4. Select the build system that you are going to use in the project.

    Template list for a new Kotlin Multiplatform project
  5. Specify the JDK that will be used in the project (version 1.8 or later is recommended). The JDK:

    • is essential for projects built with IntelliJ IDEA build system.

    • used for coding assistance in projects built with Gradle and Maven

    If you don't have a JDK installed, you can download it right in the dialog.

  6. Specify coordinates of the primary artifact: Group ID, Artifact ID, and Version. Not applicable for IntelliJ build system.

  7. Click Next to proceed to configuring the module structure. For detailed information, see New Project Wizard.

Mix Java and Kotlin in one project

You can call Java code from Kotlin and vice versa. This enables you to gradually transition a project to Kotlin or use both languages in parallel, for example, by using Kotlin for testing an existing Java codebase.

In order to start using Kotlin in your project, make sure that the Kotlin plugin is enabled and the Kotlin dependency is added to your project.

Add Kotlin dependency to an existing JVM project

  • If your project uses IntelliJ IDEA build tool, create a Kotlin file. When a notification appears stating that Kotlin is not configured for the project, click Configure, then select if you want to use Kotlin with Java or JavaScript.

    Choose configurator for Kotlin
  • For other build tools, follow the steps in:

Convert Java to Kotlin

IntelliJ IDEA allows you to automatically convert your Java code to Kotlin. The resulting code is not supposed to be perfect, however, it may be helpful in some situations.

If you are not satisfied with the result of conversion, you can roll it back with Ctrl+Z.

  1. Paste Java code in a Kotlin file. In the dialog that appears, click Yes.

  2. With a Java file open in the editor, go to main menu and select Code | Convert Java File to Kotlin File or press Ctrl+Alt+Shift+K.

Last modified: 11 April 2022