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You must have a JDK 8 or higher installed on your machine. To determine the JDK to run upon, jeka prioritizes the following, in order :

  • JEKA_JDK environment variable ([JEKA_JDK]/bin/java must point on java executable)
  • jeka.jdk.XX property definied in [JEKA_USER_DIR]/, if a property is defined in [PROJECT_ROOT]/jeka/ file.
  • JAVA_HOME environment variable
  • java executable accessible from PATH environment variable.


Jeka organization provides a plugin for IntelliJ in order to render the following tasks useless.

Here, we'll focus only on how to do it using command line only.

There are two ways of using jeka : by installing Jeka itself, or by using a project that already contains the Jeka wrapper.

Install Jeka Distribution


It is not required to install Jeka distribution to use it. If you fetch a project that already contains a wrapper, using jekaw will be enough. Nevertheless, if you want to create a project from scratch, installation will be necessary.

  • Download the latest release here and unpack the wherever you want on your machine. We'll refer to this directory as [JEKA HOME].
  • Add [JEKA HOME] to your PATH environment variable.
  • Now, you can use the jeka command from everywhere.

Projects with Jeka Wrapper

There is no need to install Jeka to work a project already holding a Jeka wrapper:

  • Fetch the project from its remote repository
  • Use the jekaw command from the project root path.


To start from an empty project, clone the blank project template from

Setup IDE

  • Add an IDE path variable JEKA_USER_HOME pointing on [USER HOME]/.jeka. In Intellij : Settings... | Appearance & Behavior | Path Variables
  • If you use jeka instead of jekaw, add an IDE path variable JEKA_HOME pointing on [JEKA HOME].

Hello World Project

For simplicity's sake, we'll use the basic example of displaying a message on the console.

Create Project Structure

  • Create the root dir of the project or use the template wrapper project mentioned above.
  • At project root, execute jeka scaffold#run scaffold#wrapper (or just jekaw scaffold#run if using the template wrapper project).
  • Execute jeka intellij#iml or jeka eclipse#files in order to generate the IDE configuration file.
  • The project with a Jeka structure and a basic build class is ready to work within your IDE

Create a Jeka Method

Jeka methods must be zero-args instance methods returning void.

Modify the def/ file to add the hello method as follows.

import dev.jeka.core.tool.JkBean;
import dev.jeka.core.tool.JkInit;

class Build extends JkBean {

    public void hello() {
        System.out.println("Hello world !");

    public static void main(String[] args) throws Exception {
        Build build = JkInit.instanceOf(Build.class, args);


Now, execute jeka hello to see the message displayed on the console.

Optionally, you can also use the classical main method to launch it from the IDE.

Get Contextual Help

Execute jeka -h (or jeka -help) to display contextual help on the console.

Follow the instructions to navigate to more specific help.


Do not confuse jeka -help and jeka #help. The latter only provides documentation about the default KBean.


For any reason, we might use different locations than the standard ones for Jeka User Home and Jeka Cache.

We can change the location using the following OS environment variables :

  • JEKA_USER_HOME : to set the Jeka User Home to a specified location (absolute path).
  • JEKA_CACHE_DIR : to set the cache (mainly all downloaded files), to a specified location (absolute path)

Or setting the following System properties :

  • jeka.cache.dir : to set the cache (mainly all downloaded files), to a specified location (absolute path)