RFE to re-purpose option --version:<version>

[Kumar Srinivasan]

Hello Paul,

There is a light weight method to get the version from the launcher,
"-fullversion" noting that, this does not invoke the VM, and obtains
the version string set at build time in the launcher itself.

However you would have to exec java twice, once to get the version,
another to invoke it.

Thanks

Kumar

> Dear Committers,
>
> In Java 9, the --version:<version> has been deprecated. The error message
> returned to me is:
>
> Error: Specifying an alternate JDK/JRE version is no longer supported.
>    The use of the flag '-version:' is no longer valid.
>    Please download and execute the appropriate version.
> Unrecognized option: -version:9
>
> I am happy with that. This is not a complain on removing that "alternate"
> feature.
>
> However, I would like to propose bringing back the option with a different
> purpose. I would like to use --version:<version> as a validation check. I
> want Java to execute ONLY if the version specified matches the actual
> platform version. This would be a wonderful help to scripts that require a
> particular version of the Java platform, and should fail if the environment
> has been accidentally setup with the wrong Java platform version.
>
> Examples:
> java --version:9
> java --version:9.1
>
> AFAICT, the only way to do this now is to execute Java twice. Once to pipe
> --version to some find/grep command and check return code, and then execute
> java again if the check pass. Loading the runtime twice is not optimal,
> wouldn't you agree? Yet if you agree to this proposal, it would be a big
> win for script writers, I believe.
>
> Opinions please. Thank you.
>
> Cheers,
> Paul