Java casting / classloader issues

Question

Here is the simplified version of the problem:

 SomeClass c = (SomeClass) obj.getSomeClassParent()

not always but it happens sometimes to t

Answer 1

i would guess that you have a problem due to the mismatch between classloaders and native libraries. native libraries are loaded and associated with a classloader, however, the programs can only really load one instance of a native library. so, if you load the native lib in classloader A, and classes which it outputs will be associated with classloader A. if you later load the same native library in classloader B, you aren't really loading it again, and it will still be passing out classes for classloader A. so, either you redeployed your webapp, or you have 2 webapps in the same webserver which use the same native library.

if possible, you should try to put the native library in the base classpath of the webserver, so that it will be loaded by the base classloader, and thus be usable by any webapp. if you can't do this, and the problem is only a redeployment issue, then you might want to undeploy and wait a bit before redeploying (in theory, the native lib will be unloaded when the classloader with which it is associated is GCed, but of course, this can take an unknown amount of time).