[jdom-interest] Serialization Trouble through Inheritance

[Björn Buchner]

Hi Folks,

I am using the JDOM 2.0.2 release and experienced some trouble when it 
comes to serialization.

De-/serializing an Element object through the standard 
ObjectOutput/InputStream is no problem. Trouble starts when I try to 
deserialize an object of a class that inherits from Element.

It always ends with a InvalidClassException: no valid constructor. 
Normally this indicates that JRE is missing a public default 
constructor, but as you can see in the example below the subclass
has a default constructor.

Thanks in advance for your help

Example code:

public class MyElement extends Element {

     private static final long serialVersionUID = -4220756491425652053L;

     public MyElement() {
         super();
     }


     public static void main(String ... args) throws IOException, 
ClassNotFoundException {
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        ObjectOutputStream outStream = new ObjectOutputStream(buffer);

        MyElement element = new MyElement();

        outStream.writeObject(element);
        outStream.flush();
        ObjectInputStream inStream = new ObjectInputStream(new 
ByteArrayInputStream(buffer.toByteArray()));
        element = (MyElement)inStream.readObject();
     }
}

Result:

Exception in thread "main" java.io.InvalidClassException: 
<packageremoved>; no valid constructor
     at 
java.io.ObjectStreamClass$ExceptionInfo.newInvalidClassException(ObjectStreamClass.java:147)
     at 
java.io.ObjectStreamClass.checkDeserialize(ObjectStreamClass.java:755)
     at 
java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1751)
     at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1347)
     at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
     at <packageremoved>.main(MyElement.java:29)

-- 
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Björn Buchner

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