Generics and Xstream

Question

I have a problem with java generics and xstream when deserializing a Xml.

This is the main DTO

@XStreamAlias("OBJECTX")
public class ObjectX<T> {

    @XStreamAlias("DATA")
    private T t;

    ... getter and setter ...

}

This is the Data object inside the main DTO

@XStreamAlias("DATA")
public class FolderXml {

    @XStreamAlias("DIGITION_NAME")
    private String digitionName;

    @XStreamAlias("FOLDER_ID")
    private int folderId;

    ...getters and setters...

}

This is the Xml example to deserialize

<?xml version="1.0" encoding="UTF-8"?>
<OBJECTX>
        <DATA>
            <DIGITION_NAME>TVC_ACT2</DIGITION_NAME>
            <FOLDER_ID>1234</FOLDER_ID>
        </DATA>
</OBJECTX>

This is the actual code

StaxDriver staxDriver = new StaxDriver(new NoNameCoder());
XStream xstream = new XStream(staxDriver);
xstream.processAnnotations(ObjectX.class);
xstream.alias("DATA", FolderXml.class);
ObjectX<FolderXml> obj=  (ObjectX<FolderXml>) xstream.fromXML(xml);

The exception is

com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$UnknownFieldException: No such field java.lang.Object.DIGITION_NAME
---- Debugging information ----
field               : DIGITION_NAME
class               : java.lang.Object
required-type       : java.lang.Object
converter-type      : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
path                : /OBJECTX/DATA/DIGITION_NAME
line number         : 4
class[1]            : cat.ccma.digition.digitionservicecontroller.objects.base.ObjectX
version             : null
-------------------------------

Answer 1

Modify your code to add default implementation for Generics.

    StaxDriver staxDriver = new StaxDriver(new NoNameCoder());
    XStream xstream = new XStream(staxDriver);
    xstream.processAnnotations(ObjectX.class);
    xstream.processAnnotations(FolderXml.class);
    xstream.alias("DATA", FolderXml.class);
    xstream.addDefaultImplementation(FolderXml.class,ObjectX.class.getDeclaredField("t").getType());
    ObjectX<FolderXml> obj=  (ObjectX<FolderXml>) xstream.fromXML(xml);