September 15, Oracle announced the general availability of “Java 15”, along with the releases of “Java SE 15 Platform” and open-source implementation “OpenJDK 15”.
Java 15 is the latest release after Java 14, released in March. Oracle has been following a six-month release cycle ever since Java 10 was released in 2018, and Java 15 also follows the release cycle. It has been 25 years since Java first came out. According to Oracle, there are 51 billion active JVMs as Java language is used for analytics, microservices, data management, and other applications.
As to the new features, this release introduces the cryptographic signatures using the Edwards-Curve Digital Signature Algorithm. Also, Hidden Classes, which cannot be accessed directly from the byte code of other classes, is introduced. It is intended to be used by frameworks that generate classes at run time and use them indirectly.
The Text Blocks, which was introduced in Java 13 as a preview feature, is now a GA feature. It brings better productivity, as the text block is multi-line literal, automatically formatting the string in a predictable way. Z Garbage Collector (ZGC), which was experimentally introduced to Java 11, is now a GA feature. Although ZGC brings low-latency and scalability, Java 15 continues to have G1 as its default garbage collector. This release introduces Sealed Classes as a preview. It restricts which other classes or interfaces may extend or implement. Records, Foreign-Memory Access API, and pattern matching for instance, which were introduced to JDK 14, will continue to be available as preview features.
This release adds many other improvements and changes.