Welcome to the seventy-ninth issue of Hashtag Jakarta EE!
I have previously described how to migrate manually from the javax.* to jakarta.* namespace in this migration guide. While this migration is a pretty easy task, it can be time-consuming and error-prone. But don’t despair, the community is coming to your help by providing tools that can do this for you, or at least assist you in the process. Just take a look at these:
The Tomcat Migration Tool for Jakarta EE provides easy-to-use command-line tooling for transforming Jakarta EE applications on the javax.* namespace over to jakarta.*. You can choose between two profiles depending on whether you are using the Jakarta EE APIs supported by Apache Tomcat, or the entire suite of specifications.
The Eclipse Transformer also provides transformation of Jakarta EE applications on the javax.* namespace to jakarta.*. It can operate on source files as well as class files and has an extensive set of configuration options. The Eclipse Transformer can also be used as a custom class loader, so it can perform the transformation at runtime.
In the upcoming 2021.2 version of IntelliJ IDEA, there will be built-in support for migrating from javax.* to jakarta.*. Check out Automatic migration from Java EE to Jakarta EE for a description of the functionality. If you look closely, you will notice that the sample application they are using is my Complete Duke application that I use to demo the namespace change. You can find it, and others in my Jakarta EE Duke sample projects. It is awesome that the folks at JetBrains found my demo app useful enough to use for showcasing this feature!
As I mentioned above, the Eclipse Transformer provides custom classloader capabilities so the namespace migration can be done at runtime. Many of the Jakarta EE implementations are using this technology in the Jakarta EE 9 and Jakarta EE 9.1 compatible products. I have included an example here of how you can run a Jakarta EE 8 application transformed to Jakarta EE 9.1 and packaged in a WildFly bootable JAR.