While the highlight features of JDK 15 include the Z Garbage Collector, text blocks, hidden classes, and previews of sealed classes, pattern matching, and records, among others.
And as JDK 15 is a short-term release, it will only be supported with Oracle Premier Support for six months; with the next release (JDK 16) scheduled to arrive next March. Meanwhile, JDK 17 will be the next Long-Term Support release to be supported by Oracle for eight years, and it's slated to arrive a year from now, given Oracle’s six-month release cycle for Java SE versions.
What's New in JDK 15?
JDK 15 features a foreign-memory access API, which enable Java programs to safely and efficiently access foreign memory outside of the Java heap. And the API operates on various kinds of foreign memory, such as persistent, native, and managed heap, with many Java programs accessing foreign memory, such as Ignite and MapDB.
The API would also help avoid the cost associated with garbage collection, sharing memory across processes, and serialize and deserialize memory content by mapping files on memory. Other new features and changes in JDK 15, includes:
- A preview of sealed classes.
- Records, which are classes that act as carriers for immutable data.
- Cryptographic signatures based on the Edwards-Curve Digital Signature Algorithm (EdDSA).
- Disabling biased locking by default and deprecating all related command-line options
- The Z Garbage Collector (ZGC) graduates from an experimental feature to a product under this proposal.
- Deprecation of the RMI Activation mechanism.
Additionally, there is the reimplementation of the legacy DatagramSocket API by replacing the underlying java.net.datagram.Socket and java.net.MulticastSocket APIs with more modern implementations that are easy to debug and maintain, with virtual threads currently being explored in Project Loom.
How to get Started with JDK 15
Oracle has mapped out the upgrades for Java, including the open-source reference implementation of version 15 of the Java SE Platform as part of a new, six-month release schedule for standard Java. Therefore, developers can take a look at JDK 15 in order to get an idea of what is expected in JDK 16.
You can also join the early adopter program by downloading the beta versions of JDK 16 to give it a spin.