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

[Bardur Arantsson]

On 20/09/2018 09.13, Eli Schwartz via arch-general wrote:
> On 9/19/18 11:50 AM, Bardur Arantsson wrote:
>> (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.)
> 
> Gosh, I'd hope the trend was instead to have modern, up-to-date releases
> that actually work properly.
> 

There's no need for snark. Java/JDK upstream take compatibility and
quality *extremely* seriously. Java releases are usually incredibly
backward-compatible, but

a) generally the JVM world is (understandably IMO) very careful in
moving from one version to next because JVM applications are usually
*huge* with many many corner cases. The JVM itself + the standard class
library is also quite big and it's basically impossible to do any change
without *something* *somewhere* relying on the existing (possibly buggy)
behavior. Most responsible developers at least try out version N+1,
report any bugs upstream and wait for those to be fixed and try out
version N+1 when the first 'wave' of bugs is fixed. While doing that,
having access to both version N and N+1 is kind of critical.

b) sometimes a new feature simply changes how something fundamentally
works and the feature is (by design) incompatible with the previous
state of things. This is the case for the 'modules' feature, for
example: It simply not possible to both have the module classpath
isolation and not have it at the same time. (It's actually possible to
disable this globally, but that's kind of a moot point.)

Regards,