Building OpenJDK

Version 3

    This section covers the myriad ways in which you can contribute to the Adopt OpenJDK program. As always the latest coding projects are on our BitBucketand GitHub repos.

    Starter Level


    Understand OpenJDK

    There's a lot to learn about the technology and the open source project


    Build OpenJDK

    Build Java itself!

    Testing (Test Fests)

    Improve the quality of Java!

    • Test Fests - Hackdays focusing on improving the quality and quantity of OpenJDK tests.
    • Testing Java - Co-ordinating projects to use early builds of Java 8/9


    Betterrev - A new website and workflow to improve patch submission process for OpenJDK. Includes:

    1. Pull Request mechanism for patch submission
    2. Build Farm
    3. Continous Integration with JTreg regression tests
    4. Static code analysis
    5. Patch creation
    6. License checking
    7. Patch submission
    8. And more



    Javacountdown - A JavaEE 6/7 and HTML 5 website to track global usage of Java in the Browser and encourage its demise.

    Javadoc Updater Tool



    • Ux overhaul of the wiki pages


    Bug fixes and small enhancements

    There are some General Instructions for Small Changes which apply to most of the sub projects below.

    Intermediate Level

    Your First Patch

    In order to get a patch ready for committing, you need to have written the patch, but there are several other things you need to do.First off, you should be comfortable with building OpenJDK & keeping up to date with the head of the relevant repo.You should also know (from having watched the mailing lists, or by asking on the Adopt OpenJDK mailing list) which project you should be targeting for your patch. Note that this may not necessarily be the OpenJDK 9 mainline project.You should also have installed jtreg as that will be needed for testing your patch.

    Java 9

    Jigsaw and OSGi

    There are two parts to this. Project Jigsaw itself and project Penrose, a splinter project investigating OSGi/Jigsaw interaction

    • Jigsaw - TBA
    • Project Penrose - Lead by Neil Bartlet


    Javadoc overhaul

    See Javadoc for details - Lead by Ben Evans and Richard Warburton


    • Investigate the experimental patch by Lukas Stadler and get it up to date with OpenJDK 9 - Join co_jsrATsswDOTuni-linzDOTacDOTat for details
    • Start discussions within mlvm-dev about coroutines, their state and their suitability going forward for the JVM


    Concurrency Testing


    Java Microbenchmark Framework

    Giving feedback, adding tutorials etc for the Java Microbenchmark framework


    Other JDK Enhancement Proposals (JEPs)

    Read Alex Blewitt's blog post for some background information on the JEP process. Some JEPs can be classed as advanced level proposals:

    • TBA

    Java 8

    Java 8 has now been released, here are the projects we ran to support it. You can still find useful tutorials and material there!


    Java 8 will include Lambdas (aka closures), bringing functional programming capabilities to Java


    Nashorn (Javascript in Java 8+)

    • For more details see the page on Nashorn


    PermGen Removal

    Misc Projects

    Delayed Projects

    • Ux overhaul of the - This is delayed until an infrastructure move takes place.
    • Triage OpenJDK Bugs - This is delayed until the public JIRA instance is available