public final class Complex implements XMLSerializable {
 
 // Use the cartesien form for the default XML representation. 
 protected static final XMLFormat<Complex> XML = new XMLFormat<Complex>(Complex.class) {
 public Complex newInstance(Class<Complex> cls, InputElement xml) throws XMLStreamException {
 return Complex.valueOf(xml.getAttribute("real", 0.0), 
 xml.getAttribute("imaginary", 0.0));
 }
 public void write(Complex complex, OutputElement xml) throws XMLStreamException {
 xml.setAttribute("real", complex.getReal());
 xml.setAttribute("imaginary", complex.getImaginary());
 }
 public void read(InputElement xml, Complex complex) {
 // Immutable, deserialization occurs at creation, ref. newIntance(...) 
 }
 };
 ...
 }