Thank you for your extensive replies!
So I will use the JDK 1.5 version until I phase out the remaining JRE 1.5. If I understand correctly, as long as you stay with the specs of the Java platform 1.5 you can use the JDK 1.5 version on JRE 1.5 and 1.6.

Regards,
Gam.

--- In Firebird-Java@yahoogroups.com, Roman Rokytskyy <roman@...> wrote:
>
> > Jaybird itself might work since it does not follow JDBC 4.0 in all its details yet, but in general using a JDBC 4.0 compliant implementation can/will(?) fail on Java 5 due to missing interfaces and classes defined in java.sql and javax.sql (especially the changes in the exception hierarchy, since there weren't any new interfaces AFAIK). Some drivers do work around that though by using factories.
>
> The interfaces are not a problem - one can always define the missing
> methods in our interfaces - I used this to mask differences between JDBC
> 2.0 and JDBC 3.0, but the classes are... We can use factories, but it
> just complicates the whole thing...
>
> Roman
>