Have you ever built your own Java Development Kit from a source?

Having the complete source code readily available, and now in a more commonly used download format, means it is easier than ever to build your own JDK. Yes, it’s a better-documented, easily configured process than in the past. But it’s still a bit confusing.

The source code for the OpenJDK recently moved from the Mercurial version control system (VCS) to the Git VCS and the GitHub repository system, and that’s probably a good thing.

In his latest article, Ian Darwin (Java Champion, the author of Java Cookbook and Android Cookbook) has explained all background information, why it matters, and what you need to know.

He covered different aspects of BitKeeper– a commercial software product by McVoy’s company, BitMover; Mercurial – one of its largest projects was Sun’s Java OpenJDK; Git and Github- Git offers branching, letting developers work on multiple sets of changes at the same time, and merging, pulling multiple branches into another branch, typically the main one. A related platform is GitHub, a cloud-based Git service with plenty of additions; etc.

One of the main questions which Ian pointed out was “Why the move, and why now?”.

Well, before the move from Mercurial, the OpenJDK lived in several repositories. It was decided that it would be best to consolidate into a single repository. Ian looked at a list of completed JEPs and project documents that provide insight into the four major stages of the GitHub consolidation and migration. In the end, he showed the audience how to Get the source code and build the OpenJDK.

The OpenJDK project has moved from Mercurial on java.net to Git on GitHub. Along the way, the eight repositories that were once needed to build the JDK were merged into one. This gives you the source code to build a complete instance of Java SE.