Parent/Child Serialization local class incompatible Exception

Question

I'm getting a serialization compatibility error from the below two classes. Only the parent class, CommericalCustomer implements serialization. What is the proper way to use the Serializable Interface when having a parent/child relation as I have below?

public class CachedCommercialCustomers extends CommercialCustomer {


}

public class CommercialCustomer implements Serializable {

    private static final long serialVersionUID = 1L;

}

Exception:

[#|2013-01-02T05:01:02.553-0800|SEVERE|glassfish3.1.2|com.hazelcast.nio.AbstractSerializer|_ThreadID=10;_ThreadName=Thread-2;|spot.api.model.vo.backoffice.CachedCommercialCustomers; local class incompatible: stream classdesc serialVersionUID = -2672531984245897526, local class serialVersionUID = -743225273062282831
java.io.InvalidClassException: com.sample.CachedCommercialCustomers; local class incompatible: stream classdesc serialVersionUID = -2672531984245897526, local class serialVersionUID = -743225273062282831
        at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:579)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1600)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1513)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1749)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346)
        at java.io.ObjectInputStream.readUnshared(ObjectInputStream.java:458)
        at com.hazelcast.nio.DefaultSerializer$ObjectSerializer.readNormal(DefaultSerializer.java:383)
        at com.hazelcast.nio.DefaultSerializer$ObjectSerializer.read(DefaultSerializer.java:353)
        at com.hazelcast.nio.DefaultSerializer.read(DefaultSerializer.java:134)
        at com.hazelcast.nio.CustomSerializerAdapter.read(CustomSerializerAdapter.java:33)
        at com.hazelcast.nio.AbstractSerializer.toObject(AbstractSerializer.java:116)
        at com.hazelcast.nio.AbstractSerializer.toObject(AbstractSerializer.java:146)
        at com.hazelcast.nio.Serializer.readObject(Serializer.java:72)
        at com.hazelcast.impl.ThreadContext.toObject(ThreadContext.java:103)
        at com.hazelcast.nio.IOUtil.toObject(IOUtil.java:149)
        at com.hazelcast.impl.BaseManager$RequestBasedCall.getResultAsObject(BaseManager.java:384)
        at com.hazelcast.impl.BaseManager$ResponseQueueCall.getResultAsObject(BaseManager.java:455)
        at com.hazelcast.impl.BaseManager$RequestBasedCall.getResultAsObject(BaseManager.java:368)
        at com.hazelcast.impl.BaseManager$ResponseQueueCall.getResultAsObject(BaseManager.java:455)

Answer 1

The problem here is that you don't specify a serialVersionId for your sub class - so java will generate one for you instead. A simple recompilation might change this value if you change the java source file. See the spec .

The fact that the I'd changes when the code changes is a good thing, but in some cases it will cause you some grief :)

See here for more information and how to "fix" the problem if necessary.