This guide explains how to set up your environment for development of JabRef. It includes information about prerequisites, configuring your IDE, and running JabRef locally to verify your setup.

The most important step is to configure your IDE.
In case you know how to install JDK14 and to fork JabRef's code,
        please scroll down to the IDE setup.

For a complete step-by-step guide for Linux using IntellJ IDEA as the IDE, have a look at the following video instructions:

​​​​

Prerequisites

This section list the prerequisites you need to get started to develop JabRef. After this section, you are ready to get the code.

Java Development Kit 14

A working Java 14 installation is required. In the command line (terminal in Linux, cmd in Windows) run javac -version and make sure that the reported version is Java 14 (e.g javac 14). If javac is not found or a wrong version is reported, check your PATH environment variable, your JAVA_HOME environment variable or install the most recent JDK.

Download the JDK from https://jdk.java.net/. On Windows, you can execute choco install openjdk (requires installation of chocolatey - a package manager for Windows).

GitHub Account

If you do not yet have a GitHub account, please create one.

Proposals for account names:

• Login similar to your university account. Example: koppor

• Use your last name prefixed by the first letter of your first name. Example: okopp

• Use firstname.lastname. Example: oliver.kopp

You can hide your email adress by following the recommendations at https://saraford.net/2017/02/19/how-to-hide-your-email-address-in-your-git-commits-but-still-get-contributions-to-show-up-on-your-github-profile-050/.

Most developers, though, do not hide their email adress. They use one mich may get public. Mostly, they create a new email account for development only. That account then be used for develoment mailing lists, mail exchange with other developers, etc.

Examples:

• Same login as in GitHub (see above). Example: koppor@gmail.com

• "it" in the name. Example: kopp.it@gmail.com

• Use the university login. Example: st342435@stud.uni-stuttgart.de

git

It is strongly recommend that you have git installed.

• In Debian-based distros: sudo apt-get install git

• In Windows: Download the installer and install it.

  Using chocolatey, you can run choco install git.install -y --params "/GitAndUnixToolsOnPath /WindowsTerminal to a) install git and b) have linux commands such as grep available in your PATH.

  For more advanced tooling, you may use Fork - a fast and friendly git client for Mac and Windows: choco install git-fork.

• ​official installation instructions​

IDE

We suggest IntelliJ IDEA or Eclipse (for advanced users) (2020-03 or newer).

Under Ubuntu Linux, you can follow the documentation from the Ubuntu Community or the step-by-step guideline from Krizna to install Eclipse. Under Windows, download it from www.eclipse.org and run the installer.

Other Tooling

See our tool recommendations.

Get the code

This section explains how you get the JabRef code onto your machine in a form allowing you to make contributions.

Fork JabRef into your GitHub account

1. Log into your GitHub account

2. Go to https://github.com/JabRef/jabref​

3. Create a fork by clicking at fork button on the right top corner

4. A fork repository will be created under your account (https://github.com/YOUR_USERNAME/jabref)

Clone your forked repository on your local machine

• In a command line, navigate to the folder where you want to place the source code (parent folder of jabref/). To prevent issues along the way, it is strongly recommend to choose a path that does not contain any special (non-ASCII or whitespace) characters.

• Run git clone --depth=10 https://github.com/YOUR_USERNAME/jabref.git. The --depth--10 is used to limit the download to ~20 MB instead of downloading the complete history (~800 MB). If you want to dig in our commit history, feel free to download everything.

• Go to the newly created jabref folder: cd jabref

• Generate additional source code: ./gradlew assemble

• Start JabRef: ./gradlew run

  • The JabRef's GUI should now start up.

Configure your IDE

These steps are very important. They allow you to focus on the content and ensure that the code formatting always goes well. Did you know that IntelliJ allows for reformatting selected code if you press Ctrl+Alt+L?

Setup for IntelliJ IDEA

IntelliJ IDEA fully supports Gradle as a build tool, but also has an internal build system which is usually faster. For JabRef, Gradle is required to make a full build but once set up, IntelliJ IDEA's internal system can be used for sub-sequent builds.

To configure IntelliJ IDEA for developing JabRef, you should first ensure that you have enabled both bundled plugins Gradle and Gradle Extension

• Navigate to File | Settings | Plugins | Installed and check that you have

  the Gradle and Gradle Extension enabled.

After that, you can open jabref/build.gradle as a project. It is crucial that Java 14 is used consistently for the JabRef project which includes ensuring the right settings for your project structure, Gradle build, and run configurations.

• Ensure you have a Java 14 SDK configured by navigating to

  File | Project Structure | Platform Settings | SDKs. If you don't have one, add a new Java JDK and point it to the

  location of a JDK 14.

• Navigate to File | Project Structure | Project and ensure that the projects' SDK is Java 14

• Navigate to File | Settings | Build, Execution, Deployment | Build Tools | Gradle and select the Java 14 SDK as

  the Gradle JVM at the bottom.

To prepare IntelliJ's build system two additional steps are required

• Navigate to File | Settings | Build, Execution, Deployment | Compiler | Java Compiler, and under

  "Override compiler parameters per-module" add ([+]) the following compiler arguments for the JabRef.main module:

   --add-exports=javafx.controls/com.sun.javafx.scene.control=org.jabref
   --add-exports=org.controlsfx.controls/impl.org.controlsfx.skin=org.jabref

• Enable annotation processors by navigating to

  File | Settings | Build, Execution, Deployment | Compiler | Annotation processors and check "Enable annotation processing"

Using Gradle from within IntelliJ IDEA

Ensuring JabRef builds with Gradle should always the first step because, e.g. it generates additional sources that are required for compiling the code. After adjusting all settings mentioned earlier, your first step should be to

• Open the Gradle Tool Window with the small button that can usually be found on the right side of IDEA or navigate to

  View | Tool Windows | Gradle.

• In the Gradle Tool Window, press the "Reimport All Gradle Projects" button to ensure that all settings are up-to-date

  with the setting changes.

After that, you can use the Gradle Tool Window to build all parts JabRef and run it. To do so, expand the JabRef project in the Gradle Tool Window and navigate to Tasks. From there, you can

• Build and run JabRef by double-clicking JabRef | Tasks | application | run.

  After that a new entry called "jabref [run]" will appear in the run configurations.

• Now you can also select "jabref [run]" and either run or debug the application from within IntelliJ.

You can run any other development task in a similar way. Equivalently, this can also be executed from the terminal by running ./gradlew run.

Using IntelliJ's internal build system

You should use IntelliJ IDEA's internal build system for compiling and running JabRef during development, because it is usually more responsive. Thereby, it's important that you understand that JabRef relies on generated sources which are only build through Gradle. Therefore, to build or update these dependencies you need to run the assemble Gradle task at least once.

To use IntelliJ IDEA's internal build system when you build JabRef through Build | Build Project or use the provided "JabRef Main" run configuration, ensure that

• in File | Settings | Build, Execution, Deployment | Build Tools | Gradle the setting "Build and run using" and

  "Test using" is set to "IntelliJ IDEA".

Essentially, you now have the best of both worlds: You can run Gradle tasks using the Gradle Tool Window and unless you haven't made changes to input files that generate sources, you can compile and run with IntelliJ's faster internal build system.

Using JabRef's code-style

Contributions to JabRef's source code need to have a code formatting that is consistent with existing source code. For that purpose, JabRef provides code-style and check-style definitions.

• Install the CheckStyle-IDEA plugin, it can be found via the plug-in repository:

  1. Navigate to File | Settings | Plugins | Marketplace and search for "Checkstyle" and choose "CheckStyle-IDEA"

  2. Close the settings afterwards and restart IntelliJ

• Go to File | Settings | Editor | Code Style

• Click on the settings wheel (next to the scheme chooser), then click "Import Scheme"

• Select the IntelliJ configuration file config/IntelliJ Code Style.xml.

• Go to File | Settings | Checkstyle | Configuration File

  1. Import the CheckStyle configuration file by clicking the [+] button

  2. For the description provide e.g. "JabRef"

  3. Click "Browse" and choose config/checkstyle/checkstyle.xml

  4. Check "Store relative to project location"

  5. Click "Next" and "Finish"

  6. Activate the CheckStyle configuration file by ticking it in the list

  7. Save settings by clicking "OK"

Troubleshooting when using both IDEA and Eclipse

If you have configured Eclipse for the same project (the required steps are described below), then the additionally added file Log4jPlugins.java must be excluded from the compilation process, otherwise an error will occur during the compilation of the project:

• File | Settings | Build, Execution, Deployment | Compiler | Excludes and add the following file to the

  list ([+]), in order to exclude it:

  • src/main/java/org/jabref/gui/logging/plugins/Log4jPlugins.java

Setup for Eclipse

Make sure your Eclipse installation us up to date, Eclipse 2020-03 or newer is required. For Eclipse 2020-03 you need to install jdk14 support​

1. Run ./gradlew run to generate all resources and to check if JabRef runs.

   • The JabRef GUI should finally appear.

   • This step is only required once.

2. Run ./gradlew eclipse

   • This must always be executed, when there are new upstream changes.

3. Copy the file Log4jPlugins.java from build/generated/sources/annotationProcessor/java/main/org/jabref/gui/logging/plugins to src/main/java/org/jabref/gui/logging/plugins/

   • Usually, the folder plugins must be created for that.

4. Open or import the existing project in Eclipse as Java project.

   • Remark: Importing it as gradle project will not work correctly.

   • Refresh the project in Eclipse

5. Create a run/debug configuration for the main class org.jabref.JabRefLauncher and/or for org.jabref.JabRefMain (both can be used equivalently)

   • In the tab "Arguments" of the run/debug configuration, enter the following runtime VM arguments:

     • Set "VM Arguments" to:

     --patch-module test=fastparse_2.12-1.0.0.jar
     --patch-module test2=fastparse-utils_2.12-1.0.0.jar
     --patch-module test3=sourcecode_2.12-0.1.4.jar
     --add-exports javafx.controls/com.sun.javafx.scene.control=org.jabref
     --add-exports org.controlsfx.controls/impl.org.controlsfx.skin=org.jabref
     --add-exports javafx.graphics/com.sun.javafx.scene=org.controlsfx.controls
     --add-exports javafx.graphics/com.sun.javafx.scene.traversal=org.controlsfx.controls
     --add-exports javafx.graphics/com.sun.javafx.css=org.controlsfx.controls
     --add-exports javafx.controls/com.sun.javafx.scene.control.behavior=org.controlsfx.controls
     --add-exports javafx.controls/com.sun.javafx.scene.control=org.controlsfx.controls
     --add-exports javafx.controls/com.sun.javafx.scene.control.inputmap=org.controlsfx.controls
     --add-exports javafx.base/com.sun.javafx.event=org.controlsfx.controls
     --add-exports javafx.base/com.sun.javafx.collections=org.controlsfx.controls
     --add-exports javafx.base/com.sun.javafx.runtime=org.controlsfx.controls
     --add-exports javafx.web/com.sun.webkit=org.controlsfx.controls
     --add-exports javafx.graphics/com.sun.javafx.css=org.controlsfx.controls
     --add-exports javafx.controls/com.sun.javafx.scene.control.behavior=com.jfoenix
     --add-exports com.oracle.truffle.regex/com.oracle.truffle.regex=org.graalvm.truffle
     --patch-module org.jabref=build\resources\main

6. Optional: Install the e(fx)clipse plugin from the Eclipse marketplace: 1. Help -> Eclipse Marketplace... -> Search tab 2. Enter "e(fx)clipse" in the search dialogue 3. Click "Go" 4. Click "Install" button next to the plugin 5. Click "Finish"

7. Now you can build and run/debug the application by either using "JabRefLauncher" or "JabRefMain". This is the recommended way, since the application starts quite fast.

Final comments

Got it running? GREAT! You are ready to lurk the code and contribute to JabRef. Please make sure to also read our contribution guide.

Common issues

Java installation

An indication that JAVA_HOME is not correctly set or no JDK 14 is installed is following error message:

compileJava FAILED
​
FAILURE: Build failed with an exception.
​
* What went wrong:
Execution failed for task ':compileJava'.
> java.lang.ExceptionInInitializerError (no error message)

Another indication is following output

java.lang.UnsupportedClassVersionError: org/javamodularity/moduleplugin/ModuleSystemPlugin has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Problems with generated source files

In rare cases you might encounter problems due to out-dated automatically generated source files. Running ./gradlew clean deletes these old copies. Do not forget to run at least ./gradlew eclipse or ./gradlew build afterwards to regenerate the source files.