Strange Serialization issue - serialVersionUID need on an interface!?!

[David Harte]

I would very much appreciate it if someone could give me their thoughts on what they think may be causing the following problem. Basically I have the following structure and am getting a local class incompatible error on the interface!

Public interface ExecutionActivity extends Serializable

Public class ExecutionActivityImpl extends AbstractObject implements ExecutionActivity �

ExecutionActivityImpl has the serialVersionUID set as follows

private static final long serialVersionUID = 1L;

I persisted objects some time back and have now changed both the interface ExecutionActivity and ExecutionActivityImpl and am getting a � �ExecutionActivity (this is an interface!); local class incompatible error : serialVersionUID = 6901�., local class serialVersionUID = 123��

I have used serialver and have confirmed that the serialVersionUID for which I am getting an error is for the Interface, is this correct? My understanding was that the serialVersionUID only needed to be set on the class.

I added the serialVersionUID to the interface and that seemed to work however I would like to confirm that this is normal behaviour. One thing to mention is that the objects were persisted using j2se 1.4.0 and read back using 1.4.2

Many thanks,

David

[jiju ka]

I don't know exactly what the problem is. It seems like a version compatability issue.

I came across similar issue in the past where the version of sdk I used to compile was different than I used for run.

Your problem doesn't seem like a class compatability issue which I had. This seems like an object compatability issue.

It could be either

Objects were instantiated in one jvm and persisted. A higher version of JVM when read this persisted object, found incompatability.

OR

The .class file changed inbetween.

Please read this
http://www.javaworld.com/javaworld/javaqa/2003-06/02-qa-0627-mythser.html