You can define your own converter. For example
import com.thoughtworks.xstream.converters.basic.DoubleConverter;
public class MyDoubleConverter extends DoubleConverter
{
@Override
public String toString(Object obj)
{
return (obj == null ? null : YourFormatter.format(obj));
}
}
and then register it in a XStream object with high priority
XStream xstream = new XStream(new DomDriver());
xstream.alias("Person", PersonBean.class);
xstream.registerConverter(new MyDoubleConverter(), XStream.PRIORITY_VERY_HIGH);
return xstream.toXML(person);