The changes in Java 9 are so extensive that we could dedicate several issues of Java Magazine and still not cover them all. Java 9 was in all ways a major release of Java and the JDK. In our previous issue, we covered some of the major changes as well as how to transition from Java 8 to Java 9. However, we were unable to cover the most important innovation in Java 9, modules. The reason for the delay was explained in my editorial in that issue: the release of much of the Java platform is a cooperative effort between Oracle and key partners as well as the community of users. Now that modules have been finalized, we have a 15-page introduction to modules written by well-known trainer Paul Deitel.
We also continue our series on language changes in this release, written by authors Raoul-Gabriel Urma and Richard Warburton, who examine additions to Optionals and Completable-Futures - two features that were made popular in Java 8 and enhanced in this release.
Finally, Java Champion Ben Evans has a look inside the JVM in JDK 9 to see how method invocation works.