IDEA

Although technically any IDE with the right extensions will do, it's recommended to use IntelliJ IDEA Ultimate. There is also the Community Edition that is completely free to use.

Kotlin is included in each IntelliJ IDEA release.

Setup IntelliJ

IntelliJ Idea > Settings > Build, Execution, Deployment > Build Tools > Maven > Importing. Check the 2 checkboxes "Sources" and "Documentation".

Intellij Idea > Settings > Editor > General > Auto Import, check Optimize imports on the fly for both Java and Kotlin.

Intellij Idea > Settings > Editor > Tools > Actions on Save, check Reformat code, Optimize imports, Rearrange code and Run code cleanup.

Install the SonarLint plugin for code quality checks.

To add git blame annotations, add the plugin GitToolBox.

Setup

Install Java

sudo apt update
sudo apt install openjdk-21-jdk

Install Kotlin

In most scenarios, installing Kotlin is not necessary. Only Java is.

Install Maven

Installing Maven, our build tool, is not required, as IntelliJ comes with a bundled version of Maven. However, installing your own version might come in handy, to be able to run Maven from the command line.

sudo apt update
sudo apt install maven

Using the Maven Wrapper in a project is also an alternative. Yet it does not hurt to install Maven globally on the system, it won't conflict.