TOPCAT and friends to Java 8?

[Mark Taylor]

Dear users of TOPCAT, STILTS and STIL,

[and apologies to readers of apps at ivoa.net who are not]

I am considering moving the target platform for TOPCAT and friends
from its current version of Java 6 to Java 8 for future releases, 
to allow me to use some more recently introduced language features.

This would go completely unnoticed by most of you, but it might 
affect some people:

 - If you are a topcat/stilts user, you will only be able to use
   future topcat/stilts releases if your java installation is
   version 8 or later.  If you are already using Java 8+ to run
   topcat, you will almost certainly notice no difference as a
   consequence of this change.  If you are using an earlier version
   (Java 6 or Java 7) you will have to upgrade your java installation
   (or maybe, just make sure that topcat is using the later java
   version that's already installed on your system) to use
   future releases.

 - If you are a software developer using starjava libraries
   (STIL or STILTS classes) as a dependency of software you are
   building, you will no longer be able to use future releases
   in this way to build for a target platform of Java 6 or 7.

Notes:
 - Java 6, 7 and 8 are sometimes referred to as Java 1.6, 1.7 and 1.8
 - You can tell what java version your topcat is running by looking
   in the JVM entry of the Help|About TOPCAT" menu item, or running
   "topcat -version" or "stilts -version".

Java 6 and 7 are now extremely old (Oracle stopped providing free 
updates in 2013 and 2015 respectively; Java 8 has been around since 
2014; the most recent release is Java 12).  I know there are still 
(about 10%? of) users still running recent topcat versions on Java 6, 
but a Java 8 version certainly exists for any but the most bizarrely 
ancient platforms, so it ought not to be too difficult to upgrade.
It's quite a good idea to do that anyway; although Java 6 still 
works fine for most things that existing topcat versions do, 
there are some issues such as out of date certificate stores, 
so that e.g. access to some HTTPS TAP services will fail, 
and more recent versions are more performant in some cases.

If anybody has concerns about this or wants to try to dissuade me,
please get in touch. 

Thanks for your attention,

Mark

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/