OpenJDK FAQ

What happens with JRockit? Will it become part of OpenJDK?Oracle engineers are currently working to merge the Oracle Java HotSpot Java Virtual Machine (JVM) and the Oracle JRockit JVM into a converged offering that leverages the best features of each of these market-leading implementations. Oracle plans to contribute the results of the combined Oracle Java HotSpot and Oracle JRockit JVMs into OpenJDK.

I heard that IBM is joining OpenJDK?Yes. Oracle and IBM announced in October 2010 that we will collaborate in the OpenJDK Community to develop the leading open-source Java SE implementation, and make the OpenJDK Community the primary location for open-source Java SE development. Oracle and IBM will support the OpenJDK development roadmap that was proposed before JavaOne 2010, which accelerates the availability of Java SE across the open-source community. The collaboration between Oracle and IBM builds on the success of OpenJDK as the primary development platform for Java SE, and of Oracle's and IBM's long history of contributions to the Java community. You can find out more about the roadmap and Oracle's plans athttp://blogs.oracle.com/henrik/2010/10/java_roadmap_from_javaone_2010.html.

Who uses OpenJDK?Major Linux distributions such as Ubuntu, Fedora or Red Hat Enterprise Linux offer OpenJDK as their default Java SE implementation. In addition, the Eclipse Community Survey 2010 found that while most Java developers use Oracle's commercial JDK releases, 21% of the developers participating in the survey used OpenJDK. Last but not least, many academic institutions publish research referencing or based on OpenJDK.

What open-source license is OpenJDK published under?
GPL v2 for almost all of the virtual machine, and GPL v2 + the Classpath exception for the class libraries and those parts of the virtual machine that expose public APIs.
Why don't you use a different open-source licensing model?
When OpenJDK was created, it adopted the most popular open-source licensing model for open source VMs at the time. The licensing model has served the project well over the years, ensuring its steady growth and adoption, while minimizing risks of proprietary forks and fragmentation.

Is Oracle JDK based on OpenJDK?Yes. Oracle JDK is based on the OpenJDK source code. In addition, it contains closed-source components. The final result is licensed under a Binary Code License.
Binary Code License是sun给JDK，JRE定的license

Doesn't OpenJDK make other Java SE implementations superfluous?

No. Java users can benefit from a choice of compatible Java SE implementations provided by multiple vendors under various commercial models. The different compatible Java SE implementations compete on aspects such as tuning to different architectures, performance, tools and deployment.