@XmlElements marked with @XmlJavaTypeAdapters?

Question

I have this situation

@XmlType(name ="", propOrder={"value"})
@XmlRootElement(name = "compound")
public class Compound extends Value {
  @XmlElements({
  @XmlElement(name="simple", type=Simple.class),
  @XmlElement(name="compound", type=Compound.class)
  })
  protected List<Value> value;
  // ...
}

So a Compound is a List of both Simple and/or Compound. Both extend from Value that is defined as

public abstract class Value implements Serializable {}

Simple is a class marked with an adapter to marshal/unmarshal to/from a simple string

@XmlJavaTypeAdapter(SimpleAdapter.class)
public class Simple extends Value {
  private java.lang.String simple;
  // ...
}

Compound does not need an adapter.

The problem is that if I use a Simple 'as is', it correctly marshals/unmarshals as

<simple>my.text.here</simple>

but if I use it inside a Compound it outputs something like

<compound>
  //...
  <simple>
    <value>my.text.here</value>
  </simple>
  //...
</compound>

And I'm just wondering why... Do I miss something? How can i remove that 'value'? It seems to me that the Adapter is not used at all, is it possible to use adapters in types marked inside @XmlElements?

EDIT

After few tests i found that the problem could be in how i handle a Simple instance. So I simplify my initial question in:

Given the a Simple class like

@XmlRootElement("simple")
public class Simple {
  private java.lang.String innerText;
  // getters/setters
}

how can i obtain a marshalled output like

<simple>
  my.inner.text.here
</simple>

instead of

<simple>
  <value>my.inner.text.here</value>
</simple>

?

Peasant

A minor thing. You wrote both Compound and Simple inherit from Value, but that isn't reflected in their definitions. – Bigamist

Another thing. Are you sure the output if marshalled within Compound is <simple><value>my.text.here</value></simple> and not <simple><simple>my.text.here</simple></simple>? I would understand the latter, but I don't see why would the former happen. Where's the value element name defined? – Bigamist

All in all, it looks like you have far bigger model and you are manually extracting the most key things and posting it here. I am not sure if you run them. Maybe it would be great if you extracted a simple example (as you try), run it and share the whole context and outcome with us? – Bigamist

You are right, this is just an extract of a bigger generated (and much edited) schema that i'm not totally allowed to post. Anyway i'll try to make a simple testcase to show what i mean. I've edited the sample to fix inheritance, and no i don't know where that 'value' comes from. – Peasant

The reason I posted these comments is tried something what I thought follows your description, but my results were different. And as usual these are the details which matter. I totally understand posting the whole model might be out of question, but even it was possible it wouldn't constitute a good example. – Bigamist

After few tests i simplified the question. – Peasant

Answer 1

It sounds like you want private java.lang.String innerText; to be the @XmlValue of your Simple class. Try to annotate the String in Simple with the @XmlValue tag:

@XmlRootElement("simple")
public class Simple {
  @XmlValue
  private java.lang.String innerText;
  //getters/setters
}

Or if you were using annotations on your getter method (which I assume based on your XML output in the question change your @XmlElement tag to a @XmlValue tag:

@XmlValue
public java.lang.String getInnerText() {
  return innerText;
}

When I do this I get the output you are looking for in your edited question.

Sola

Thank you, now the problem is another one... Simple class extends an abstract base class called Value. When i try to marshall it, i get something like "The property or field s can not be annotated with XmlValue since it is a subclass of another class". How con i solve this? – Peasant

Ok, add @XmlTransient to the Value class. That should solve the problem. – Sola

@ciosbel did you try the @XmlTransient annotation on the Value class? It gave me the result you were looking for with the implementation I provided above. – Sola

Answer 2

The answer given by bamana is correct, however the exception you are seeing is due to a bug in the JAXB reference implementation. This bug also existed in EclipseLink JAXB (MOXy) but has been fixed in the 2.3.0 stream, a nighty download can be obtained here:

• http://www.eclipse.org/eclipselink/downloads/nightly.php

As a workaround you could use the XmlAdapter approach that was in your original question:

SimpleAdapter

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class SimpleAdapter extends XmlAdapter<String, Simple> {

    @Override
    public Simple unmarshal(String v) throws Exception {
        Simple simple = new Simple();
        simple.setSimple(v);
        return simple;
    }

    @Override
    public String marshal(Simple v) throws Exception {
        return v.getSimple();
    }

}

Simple

import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlJavaTypeAdapter(SimpleAdapter.class)
public class Simple extends Value {
    private java.lang.String simple;

    public java.lang.String getSimple() {
        return simple;
    }

    public void setSimple(java.lang.String simple) {
        this.simple = simple;
    }

}

Compound

import java.util.List;

import javax.xml.bind.annotation.*;

@XmlRootElement(name = "compound")
@XmlAccessorType(XmlAccessType.FIELD)
public class Compound extends Value {
    @XmlElements({ @XmlElement(name = "simple", type = Simple.class),
            @XmlElement(name = "compound", type = Compound.class) })
    protected List<Value> value;

    public List<Value> getValue() {
        return value;
    }

    public void setValue(List<Value> value) {
        this.value = value;
    }

}

Value

import java.io.Serializable;

public abstract class Value implements Serializable {}

Demo

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Compound.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        Compound compound = (Compound) unmarshaller.unmarshal(new File("input.xml"));
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(compound, System.out);
    }

}

input.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<compound>
    <simple>
        <simple>FOO</simple>
    </simple>
    <compound/>
</compound>

Wyon

That was exactly my original idea, but i don't want a simple to be marshalled like your input file, without that inner <simple> wrapper. – Peasant

@ciosbel - I believe the behaviour you are seeing is a bug, I am currently trying to fix this behaviour in EclipseLink JAXB (MOXy). However if you do use MOXy you can just use the @XmlValue without the @XmlJavaTypeAdapter anyways. – Wyon

@ciosbel - You can track the progress of this issue in EclipseLink JAXB (MOXy) via the following bug: bugs.eclipse.org/347026 – Wyon

So this is a bug. Thank you. If it's painless I'll try to switch to the MOXy implementation and test the @XmlValue hint. – Peasant