Which Java should you get?

All distributions of Java since Java 11, including Oracle’s distribution, are based on the OpenJDK source code. It should not matter whose distribution of Java you choose if it has passed the TCK. If you do not have a distribution you must use, then I recommend the Eclipse Adoptium version called Temurin. This version has passed the TCK. Java is a registered trademark, so the word cannot be used for distributions other than from Oracle, hence the name Temurin. If you are curious about where this name came from, I will give you a hint – it is an anagram.

You might think that the obvious choice for a Java distribution would be an Oracle-branded version. This was pretty much the case until the final release of Java 8. With this release, Oracle required companies that distributed Java as part of their commercial offerings to purchase a commercial support license for access to updates to Java. Starting with Java 11, Oracle required commercial licensees to purchase a subscription for every developer. Personal use of the Oracle-branded JDK has remained free to use, though.

This gets confusing because should you choose to use the OpenJDK distribution or any other distribution based on the OpenJDK except for Oracle’s, there are no fees required for commercial distribution. With the release of Java 17, Oracle changed its licensing again. Now called the Oracle No-Fee Terms and Conditions (NFTC), this now allows you to use Oracle’s Java for the development of software and then distribute this version of Java with your program without the need for a subscription or fee. This is only applicable to versions of Java starting at 17. Versions from 8 to 16 are still subject to the licenses.

How is Java licensed?

If you plan to use Java to develop software commercially, then how it is licensed is important to you. As already stated, the OpenJDK carries the GNU General Public License version 2, commonly referred to as the GPLv2. The GPL is widely used in open source software. At its most basic level, it requires any software that uses GPL licensed code to also be subject to the GPL. This means that any software you create must make its source code available under the same conditions. Copyright and intellectual property rights stay with the author of the work, either Oracle or you.

Java’s GPLv2 carries with it the Classpath Exception, also called the linking exception. A classpath, like an operating system path, is the location of classes and packages that the JVM and Java compiler will use. Under this exception, you do not need to supply the source code when you distribute your application. The software you write that is linked to Java does not require a GPLv2 license. It can remain proprietary and cannot be freely used like GPL software. You choose the licensing for the code that you generate.