This article is supposed to be an up-to-date source of curated information about changes that arrived in Java recently, and these that are about to – everything condensed into just a few minutes of reading.
After adopting a new cadence-based release cycle, new Java versions started appearing like crazy, and if you haven’t caught up yet – this is an excellent place to start.
Last update: 11.06.2021
Main Source of Confusion: New Release Cycle
In the past, Java releases were driven by prominent features like Lambda Expressions or Generics. Unfortunately, this approach ended up being quite harmful since numerous improvements could not be released until the main feature was ready.
Now, a Java version appears every six months and all the ready features, get released, which speeds up the evolution of Java – which is a great thing on its own but can generate confusion for people that got used to the fact that one would expect a new Java version to be released after years not months of waiting. We’re also more likely to see more Preview, Incubating, and Experimental features.
But not all Java versions are made equal – only one release every three years can be considered LTS (Long Term Support) with the last LTS being Java 11.
Java 9 was the last feature-oriented Java release ever and featured an impressive number of 81 JEPs.
The most important addition was JPMS (also known as Project Jigsaw), but besides that we got:
- VarHandles – public sun.misc.Unsafe replacements
- JShell – a dedicated REPL (Read-Eval-Print-Loop)
- G1 as the default garbage collector
- StalkWalking API – API providing lazy access to the information in stack traces.
- Convenience Factory Methods for Collections – collections can be now initialized using of() methods
Release date: 21 September 2017
Java 10 was the first one to be released under the new release cycle. Hence it featured only 12 JEPs and various small API additions accumulated within six months after Java 9 was released.
Among other stuff, we received new handy Collectors to be used with unmodifiable collections:
Release date: 20 March 2018
Java 11 (LTS)
Java 11 was the first Long-Term-Support release and featured 17 JEPs.
The most notable changes involved the addition of HTTPClient, Flight Recorder, experimental low-pause garbage collector(ZGC), and an experimental no-op garbage collector(Epsilon). Additionally, Java EE and CORBA modules got removed, and Nashorn deprecated.
And a few interesting methods in String API:
Release date: 25 September 2018
Another relatively small release featuring only 8 JEPs.
Release date: 19 March 2019
The smallest release to date bringing only 5 JEPs.
Release date: 17 September 2019
Java 14 had quite a few interesting additions:
- Pattern Matching for instanceof (preview)
- JFR Event Streaming
- Records (preview)
- Helpful NullPointerExceptions with extra hints what caused it
- Switch Expressions get promoted to standard
- and CMS garbage collector permanently removed
Release date: 17 March 2020
Java 15 is already out and brought a few interesting additions:
- Nashorn and biased locking removed
- Text Blocks, ZGC and Shenandoah GC promoted to standard features
- Sealed(Preview) and Hidden classes added
- DatagramSocket API reimplemented
As well as second previews of:
Release date: 17 September 2020
Java 16 brought some cool additions:
- Records were promoted to GA
- jpackage was promoted to GA
- Unix Domain Socket Channels support
- Elastic metaspace (to minimize metaspace waste)
- ZGC improvements (Concurrent Thread-Stack Processing)
- Vector API (incubator)
Release date: 16 March 2021
Java 17 will be considered an LTS release. This means that you can safely migrate from Java 11 and not worry about the next migration for a couple of years (at least if you choose to take the blue pill).
Java 17 is now feature-complete, the most notable features involve:
- Sealed Classes becoming production-ready
- Introduction of switch-case pattern matching (preview only!)
Other than that we can anticipate enhanced pseudo-random numbers generators, deprecation of the Applet API, and… a controversial decision to remove experimental support for AOT and Graal(don’t mix with GraalVM) JIT compiler and deprecate the Security Manager for removal.
There’s also a quite interesting last-minute change:
JDK 17 is now feature complete.
One of the last minute enhancements was a new JFR event (jdk.SystemGC). If you have lurking System.gc() calls in your Java code, you can now see the stack trace in JDK Mission Control. @ID_AA_Carmack
— Erik Gahlin (@ErikGahlin) June 10, 2021
Release date: ~September 2021