Java 11 vs. Java 17 — What's the Difference?

Java 11, released in September 2018, is the first long-term support (LTS) release after Java 8. It introduced several key features like the HttpClient API to replace the legacy HttpUrlConnection, and the var keyword for local variable type inference. Java 17, a later LTS release that came out in September 2021, includes all the features from Java 11 plus enhancements such as pattern matching for switch expressions and sealed classes.

In Java 11, the JEP 320 removed the Java EE and CORBA modules as part of the module system introduced in Java 9, streamlining the JDK for smaller and more maintainable builds. Java 17 continues this simplification and modularization, introducing JEP 410 which removes the Experimental AOT and JIT compiler. This reflects a shift towards JIT compilation for performance optimization.

Java 11 marked the beginning of a new six-month release cadence for Java, aiming to bring more frequent updates and feature releases to the language and platform. Java 17, while also an LTS release, benefits from this faster cycle, incorporating improvements from interim versions such as Java 12 through 16, representing a more mature ecosystem with newer features.

One of the improvements in Java 11 includes the new Z Garbage Collector (ZGC) for low-latency garbage collection. By Java 17, ZGC had become fully production-ready and was complemented by other GC enhancements like the Elastic Metaspace, which improves memory footprint and performance.

Java 11 ceased the availability of public updates for commercial use without a license. In contrast, Oracle's release of Java 17 came with the announcement that it would provide free commercial-use updates for the version until at least a year after the subsequent LTS release, signaling a significant licensing and support policy change.