RE: RPG, JVM and ClassPath V7R1

... the directory for the Java extension mechanism normaly is /QIBM/ProdData/Java400/ext and additional /QIBM/UserData/Java400/ext, not depending on the java version; this is documented in the JDK docu of AS/400 (and all compatible systems). I have found lots of rubbish here in most installations!!!
I don't use JNI calls from RPG to Java and I don't recommend this, because:
- it's near to impossible to controll the JVM properties (you have maybe one of the problems)
- the JNI support is buggy (never saw a "crashing" JVM without usage of RPG JNI calls)
- starting multiple JVMs is not recommended (Performace capabilities reference V7R1 page 176)
I'm using one prestarted JVM serving multiple RPG clients in a multithreaded environment since about ten years (I have published this later on as OpenSource Framework AppServer4RPG - BTW: ArdGate is running on AppServer4RPG with very nice performance and scalability).
So I have none experience with RPG JNI calls of my own.

For further investigation maybe you could do:
- hava look to the ext directories, if there might be an outdated version of one of your jar files
- superseed the ext mechanism by setting the java property extdirs before starting the JVM
- start the JVM with -verbose
(I don't know, how to manage last 2 recommendations, as I (nearly) never used the RPG/JNI stuff)

Dieter Bender