Exception occurred: java.lang.IncompatibleClassChangeError: Uninplemented i

Question

Hello all,
I have a problem when I try to access AS400 with CrEme in my PDA.
I have CrEme Evaluation Version V.4 in my Motorola MC55.
For developing I have used Netbeans 6.7 with pJSCP V4.12 Emulator
In addition, jars included are:
jt400Micro.jar (for accesing AS400)
symbolclases.jar (Symbol Mobility Developer Kit v1.4 for Java for scanning in the PDA)
When I launch the application, It works fine, and I can scan with the PDA barcodes.
But when I try to access to AS400, in the line -> com.ibm.as400.micro.JdbcMeDriver.getConnection(),
Exception occurred: java.lang.IncompatibleClassChangeError: Uninplemented interface method
It seems a problem with JDK but, that driver needs JDK 1.2 and CrEme V.4 support until JDK 1.3.
Do you Know what problem can be?
I hope your answers. Thanks in advance.

Answer 1

an IncompatibleClassChangeError usually results when you have versioning problems in a serialized class. Usually the problem goes like this:
You make a class, and make it serializable,
You store the class persistently somewhere, or leave a process running with a serialized version of the class available,
Then, you make a change to the class, and recompile the class.
You try to de-serialize the first version of the class into the second version of the class.
There are rules around what constitutes a compatible change to a serializable class, and what will break this. It is quite inflexible, that is why there are many caveats in the swing classes about not using Serializable for persistence (better to use xml in many cases).
I recommend reading the serialization specification, particularly the part about versioning classes.
Dave