Inheritance not working properly on saving XML

Question

I am finding that when an object is written out to an XML file, the wrong class
name is used.
Specifically, I have a class MSIDTO that inherits from DTO. Another class, DTOCollection,
can contain DTOs.
I want to be able to add MSIDTOs to my DTOCollection, save the collection to disk,
read it back in again, and get back my original MSIDTOs. But when I do this,
they are written (and hence read back) as DTOs.
Here is my schema:
<xs:element name="DTOCollection">
<xs:complexType>
<xs:sequence>
<xs:element name="DTO" type="dto:DTO" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:complexType name="DTO"/>
<xs:complexType name="MSIDTO">
<xs:complexContent>
<xs:extension base="dto:DTO">
<xs:sequence>
<xs:element name="id" type="xs:long"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
I write out this schema with the following code:
XmlDTOBean[] dtoArray = new XmlDTOBean [towrite.size()];
//populate array with MSIDTOs
XmlDTOCollectionDocumentBean.DTOCollection collect =
dtos.addNewDTOCollection();
collect.setDTOArray(dtoArray);
//save array
dtos.save(new File ("c:/temp/problem.txt"));
I would expect that the resulting XML file should contain MSIDTOs, since the objects
in the array are actually MSIDTOs. However, the elements are actually DTOs.
(They nonetheless have an ID, even though only MSIDTO has this attribute)
<DTO>
<id>2</id>
</DTO>
<DTO>
<id>3</id>
</DTO>
Apparently, they are DTOs because dtoArray is declared to be an array of XMLDTOBean.
How can I force the file to contain the actual object type, not the type of the
containing array? (I can't simply change the type of the containing array, because
DTO will later have many subclasses.)
Thanks in advance,
Carl

Answer 1

hi,
i'm getting exactly the same error.
did you find out any solution to this problem??? any pointers would be useful.