>When I tried it in the past (for Jaybird) I ran into problems, it might have been an IncompatibleClassChangeError (or subclass) on classloading time, but I can't remember the exact details. I tried reading the JLS and JVM spec on this point, but I find it hard to come to a conclusion, so I will try a small experiment this weekend.
Let's base further discussions on your weekend's test results aka hard facts. :-) >However that is half of your problem. The other half is that you risk using classes, methods or maybe even features that are not available in a lower Java version and that will not be detected compile time, but only at runtime (and not just in newly added JDBC 4.2 methods).
This can most simply be detected by a "jre6 compliance" test drive with explicit JRE6 runtime lib in bootclasspath. -Markus