What JAXB needs a public no-arg constructor for?

Question

What does JAXB need a public no-arg constructor for, during marshalling?

 Marshaller msh = ctx.createMarshaller();
 msh.marshal(object, System.out);
         


        

Answer 1

As others have noted, it shouldn't really need one but (at least in Sun's implementation) it does. You can get around this with a dummy constructor:

private MyObject() {
    throw new UnsupportedOperationException("No-arg constructor is just to keep JAXB from complaining");
}