[arch-general] How to have multiple JDKs parallel?

[Bardur Arantsson]

On 19/09/2018 17.00, Carsten Mattner via arch-general wrote:
> On 9/19/18, ProgAndy <admin at progandy.de> wrote:
> 
>> There are LTS releases planned by AdoptOpenJDK, though. For now, Java 8
>> and Java 11 are declared as supported until at least 2022 [1]. These
>> versions may be of interest for Arch Linux.
> 
> I'm not a Java developer anymore and probably unaware of new stuff,
> and what you say makes sense. Though, isn't LTS packaging a niche
> feature in Arch and wouldn't Arch follow the current latest JDK.
> So JDK-LTS would be an extra package while a hypothetical meta
> package like openjdk would track latest stable branch. Make sense?
> 

In the specific case of Java 8 (LTS by AdoptOpenJDK) -> Java 11 (LTS by
AdoptOpenJDK), I suspect that there will be a hard requirement for most
Java developers to have support for both simultaneously on their
development machines because of the whole "module" thing; see below.

Of course that support would ideally come via the distribution and
there's a similar precedent for e.g. the node.js LTS releases, I imagine
for similar reasons to do with large incompatible changes. Anyway, if
such support is not offered, I'm pretty I certainly will be forced off
Arch Linux for practical reasons.

Btw, even though the Java language and the byte code are very stable
"formats", there Java 8 -> Java 9 module transition has been everything
but trivial and has required a lot of tooling/build changes which would
be really hard to do across all of the ecosystem at once and any similar
change in the future could hold up a a Java N -> Java N+1 migration for
a pretty long time since everybody moves at their own pace.

(One *hopes* that the trend will become that only the LTS-labeled
versions will be used for actually releasing stuff to the world, but
that the intermediate versions will be more seen as experimental. That
would mean that Arch would only have to care about LTS releases.)

Regards,