JDK 12: RC feedback

[Alex Buckley]

On 2/19/2019 9:03 AM, Andrew Guibert wrote:
> 2) The java.class.version has increased (again) Looking through the
> release notes, I don't see any major bytecode improvements that
> signal to me that the class file major version needed to be
> incremented. Is this being incremented as part of some automatic
> policy?

Yes. The class file format's major version is tied to the Java SE 
Platform version, which is incremented every six months. I recall some 
discussion of the policy of tying versions, but do not have it to hand.

As to the forthcoming release: the Java SE 12 Platform standardizes the 
concept of _preview features_ [1], and this concept has consequences for 
the abstract Java Virtual Machine [2]. Namely, it is necessary to 
introduce a new major version because the semantics of the minor version 
are changed going forward.

Alex

[1] 
http://cr.openjdk.java.net/~iris/se/12/latestSpec/index.html#Preview-features

[2] 
http://cr.openjdk.java.net/~iris/se/12/latestSpec/java-se-12-annex-3.html -- 
see JVMS12 §4.1