Oracle announced the general availability of JDK 21 on September 19, 2023. Oracle will offer long term support for Java 21 for at least eight years.
What is New?
Java 21 delivers tens of new features and enhancements along with thousands of performance, stability and security updates.
The 15 JEPs (JDK Enhancement Proposals) delivered with Java 21 are grouped into 6 categories mapping to key long-term Java technology projects and hardware support.
- Project Amber: The goal of Project Amber is to explore and incubate smaller, productivity-oriented Java language features.
- Project Loom: Project Loom strives to simplify maintaining concurrent applications in Java by introducing virtual threads and an API for structured concurrency, among other things.
- Project Panama: Project Panama aims to improve the connection between the JVM and foreign (non-Java) libraries.
- Core Libraries
- Performance Updates
- Maintenance and Deprecation
Details for each JEP can be read from the links above. I marked the most important JEPs as bold for readability.