Frequented Asked Questions¶

Network - Security¶

My organization prevents access to Maven Central. What can I do?¶

You can configure Maven repositories in a central place by editing the [USER HOME]/.jeka/global.properties file.

To fetch JeKa distributions, specify the jeka.distrib.location property, pointing to a URL file. This property is better placed in the jeka.properties file, as it may vary from one project to another.

My organization prevents downloading JDKs. What can I do?¶

You can specify a local location for each JDK version you are using as follows:

jeka.jdk.11=/my/path/to/jdk11/home
jeka.jdk.17=/my/path/to/jdk17/home
...

This information can be stored in the project's jeka.properties file, in [USER HOME]/.jeka/global.properties, or passed as environment variables.

I'm behind a proxy, how should I configure Jeka ?¶

JeKa just leverages the standard Java mechanism to handle proxy. For example, You can :

Set the JAVA_TOOL_OPTIONS environment variable as -Dhttps.proxyHost=my.proxy.host -Dhttps.proxyPort=8888
Or specify proxy properties to the jeka command line, as : -Dhttps.proxyHost=my.proxy.host -Dhttps.proxyPort=8888

See here for more details on arguments.

Legacy Tools¶

How can I use Maven/Gradle in conjunction with JeKa?¶

Nothing prevents using JeKa alongside Maven or Gradle in the same project, except that in an IDE, synchronization may interfere between the two systems.

To avoid this, the jeka-src folder should exist in its own IntelliJ module. JeKa provides a simple way to accomplish this.

Using IntelliJ Plugin:

Right-click on the jeka-src folder, and a menu entry will allow you to turn the jeka-src directory into a module.

Using the Command Line:

In your existing Maven/Gradle project, do the following:

Execute: jeka base:scaffold. This generates the folder/file structure for JeKa.
Execute: jeka intellij:jekaSrcAsModule in the root directory.

This will add the property @intellij.imlFile=jeka-src/.idea/jeka-src.iml to your jeka.properties file.

Note

The jeka-src folder should now exist in its own IntelliJ module. If your IDE does not reflect this change, close and reopen the project.

Now, the jeka-src folder is managed in its own IntelliJ module. Simply execute jeka intellij:iml to sync JeKa without affecting Maven/Gradle.

Warning

Do not remove the @intellij.imlFile=jeka-src/.idea/jeka-src.iml property from the jeka.properties file, or you may face synchronization issues.

How can I migrate my project from Maven ?¶

JeKa helps translating all dependencies declared in a Maven project into the equivalent Java code.

Assuming Maven is already installed and there is a pom.xml file at the root of the project, execute jeka maven: showPomDeps to display Java code/configuration to copy-paste in a build class or dependencies.txt file.

Performance - Caching¶

How to cache downloaded dependencies in Github-actions ?¶

JeKa caches downloaded dependencies (JDKs, JeKa distros, Maven artifacts, NodeJs exe,...) in a single directory at [USER HOME]/.jeka/cache.

When running as Github Action this directory is empty at the start of the build. We need to save/restore it in order to make it persist from one build to another.

For this, we can use cache action as follow:

    - name: Restore JeKa cache
      uses: actions/cache/restore@v4
      with:
        path: ~/.jeka/cache
        key: ${{ runner.os }}

    - name: Run some JeKa commands
      run: "./jeka project: pack ..."

    - name: Save JeKa cache
      uses: actions/cache/save@v4
      with:
        path: ~/.jeka/cache
        key: ${{ runner.os }}

Misc¶

How do I configure projects from code ?¶

If you want to configure a project programmatically, either within the project itself or to create a plugin, you should access the JkProject instance directly instead of using the ProjectKBean.

The ProjectKBean initializes the project and configures it with its own settings in its init method. After that, it should not be modified. If you change the ProjectKBean instance in your code, the underlying JkProject instance will already have been configured by the ProjectKBean, meaning your changes will have no effect.

public class Build extends KBean {

    JkProject project = load(ProjectKBean.class).project;

    void init() {
        project.testing.testProcessor.engineBehavior.setProgressDisplayer(STEP);
        ...
    }
}

How can I use Eclipse compiler in Jeka ?¶

Jeka can use any JSR199 Java compiler to compile your Java code. Just set the compiler instance you need as :

import org.eclipse.jdt.internal.compiler.tool.EclipseCompiler;

@JkDep("org.eclipse.jdt.core.compiler:ecj:4.6.1")
public class Build extends KBean {

    JkProject project = load(ProjectKBean.class).project;
    ...
    project.compilerToolChain.setCompileTool(new EclipseCompiler());

    // You may pass additional options to the compiler
    project.compilation.addJavaCompilerOptions(...);
}

This works out-of-the-box when using Java 8. Using Java 11+ may require specific options to pass to the compiler.

How can I sync Eclipse/IntelliJ without using `ProjectKBean`?¶

ProjectKBean and BaseKBean provide IDE synchronization out-of-the-box, but you may prefer not to use them.

If you use a different structure to build your project, simply let your KBean implement JkJavaIdeSupport and implement the required method to provide the information necessary to generate IDE metadata files.

For synchronization, just execute jeka intellij:iml as usual.