In this chapter, we browsed through the various additions and modifications to JDK 12, barring one of its preview language features of switch expressions.

The features covered in this chapter were mostly related to the JDK and its implementation. We covered one of the newest additions to the growing GC family—Shenandoah. A concurrent GC, Shenandoah promises ultra-low pause times for modern Java applications, irrespective of their memory sizes. The other two GC features mentioned—abortable mixed collections for G1 and promptly return unused committed memory from G1—also enhance the existing G1 GC.

The JVM constants API introduces a new package and classes to represent class constraints symbolically. Apart from easing its usage across libraries and classes, the JVM constant API will standardize the constants. Default CDS archives improve the process of the creation of archive files. The removal of the source for an AArch64 ARM port is more related to housekeeping.

In the next chapter, we will look into the details and features of Project Amber.