Appendix A: Java Modules
Java 23 was released on September 17, 2024. The Java world has changed a lot since I, the author, was first introduced to the Java language. Nowadays, Java is still free, but the Oracle JDK isn’t. Developers can use the Oracle JDK to learn, but applications that are deployed in production require a license.
The workaround is to use an OpenJDK like the Eclipse Temurin1 build, but this does not come with Oracle support. JDK 23 is not a major release—it will not benefit from long-term support—but this book is still valuable because it covers the best features in the current Long-Term Support (LST) version, Java 21, and introduces you to what to expect from Java 25, the next LTS version.
If you are curious about the Oracle terms ...