Runtime.Version

[Robert Scholte]

For several plugins we need to compare the Java version. That's not always  
the Runtime used by Maven, but another (often older) installed JRE/JDK,  
e.g. by calling javadoc -J-version or java -version and parsing its output.
If would help us if we could implement our own parsing strategy and get a  
Runtime.Version for comparison. All currently exposed segments won't help  
here and as said I wonder where these are actually used apart from the  
compareTo-method.
Otherwise we're reinventing/reimplementing the comparison algorithm of  
JEP223 too.

thanks,
Robert

On Tue, 11 Jul 2017 19:27:02 +0200, <mark.reinhold at oracle.com> wrote:

> 2017/7/8 10:44:11 -0700, Remi Forax <forax at univ-mlv.fr>:
>> this is the JDK version as specified by JEP 223 [1], this is not an
>> artifact version, this is the JDK (as a whole) version.
>
> Correct.
>
>> The ModuleDescriptor.Version [2] is the module version, something like
>> your artifact version.
>
> Right, and it's more abstract than `Runtime.Version` for exactly the
> reasons that Robert mentioned.
>
>> The JDK version is loosely related to a module version because they
>> some version components like starting with 9.
>>
>> That's said, i'm not sure the JDK version is something that should be
>> checked/compared in the code, after all people can build there own JDK
>> with their own version.
>
> You'd have to hack the JDK build system pretty heavily in order to use
> a version string that's not parseable as a `Runtime.Version`.  I'm not
> sure why anyone would do that.
>
>>                          You can use the java.base version instead,
>> there is a signing mechanism (the module hashes) that ensures that the
>> jdk modules and the java.base module are compatible.
>
> The build system ensures that the version strings of all modules, and of
> the JDK itself, are the same even though module versions are represented
> as instances of `ModuleDescriptor.Version` and the platform version is
> represented as a `Runtime.Version`.
>
> - Mark