Upgrading DataNucleus DB engine (Neodatis) to latest version generates ClassCastException

Question

I'm running DataNucleus with NeoDatis as the data store.

The version that DataNucleus ships is 1.9, I'd like to upgrade to 1.9.30 (due to some odd exceptions I'm debugging in NeoDatis).

When I swap out the NeoDatis jar file that came with DataNucleus with the current one from NeoDatis I get a class cast exception on org.neodatis.odb.core.query.AbstactQuery.

But that class clearly exists in the updated jar file, Eclipse finds it for auto complete. I'm darn sure it's in the classpath.

Any thoughts?

Answer 1

A ClassCastException does not arise from a missing class (that's what NoClassDefFoundError is for); instead, it's thrown because the code attempted to cast an object to an incompatible type.

In this instance, it means the new version of NeoDatis is not completely backward-compatible with the version you had.

Do you have a full stacktrace for the ClassCastException? I'll update this with some concrete answers after I study the stacktrace. :-)