Jaxb and Object class do not get the value from the Xml when unmarshal

Question

I have a problem with the following source code. After unmarshalling the "Simple" class, the property "content" created from the "content" tag is null. I mean the "content" property don't get the value "123456" from the xml.

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Simple", propOrder = {
    "content"})
public class Simple extends Valor{

    @XmlElements({
        @XmlElement(name="content",type=String.class),
        @XmlElement(name="content",type=Integer.class),
    })
    protected Object content;

    //getters y setters
}

file.xml

<simple>
    <content>
        123456
    <content>
</simple>

Valor class

@XmlSeeAlso({
Varios.class,
Simple.class,
Grilla.class
})
@XmlTransient
public abstract class Valor {
    public abstract String getValorString();
}

Any thoughts? Thanks in advance!

Adding some clarity to the issue I'm having. If I put the Simple class:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Simple", propOrder = {
"content"})
public class Simple extends Valor{

    @XmlElements({
        @XmlElement(name="content",type=String.class),
        @XmlElement(name="content",type=Integer.class),
    })
    protected Object content;

    //getters y setters
}

if the xml is:

<simple>
<content>
    123456
</content>
</simple>

the output is:

123456

but if the xml is:

<simple>
<content>
    Hi!!
</content>
</simple>

the output is:

null

Now if the Simple class, exchange the XmlElements as in the following code:

    @XmlElements({
        @XmlElement(name="content",type=Integer.class),
        @XmlElement(name="content",type=String.class)
    })
    protected Object content;

if the xml is:

<simple>
<content>
    123456
</content>
</simple>

the output is:

null

but if the xml is:

<simple>
    <content>
        Hi!!
    </content>
</simple>

the output is:

Hi!!

Answer 1

I haven't been able to reproduce what you are seeing. Below is what I have tried.

Java Model

Simple

Below is what I implemented for your Simple class.

import javax.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Simple", propOrder = {
    "content"})
public class Simple extends Valor{

    @XmlElements({
        @XmlElement(name="content",type=String.class),
        @XmlElement(name="content",type=Integer.class),
    })
    protected Object content;

    public Object getContent() {
        return content;
    }

    @Override
    public String getValorString() {
        throw new UnsupportedOperationException();
    }

    public void setContent(Object content) {
        this.content = content;
    }

}

Demo Code

input.xml

Below is the input document with the close tag for content corrected.

<simple>
    <content>
        123456
    </content>
</simple>

Demo

import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        StreamSource source = new StreamSource("src/forum22911170/input.xml");
        Simple simple = unmarshaller.unmarshal(source, Simple.class).getValue();

        System.out.println(simple.getContent());
    }

}

Output

Below is the output from running the demo code:

123456

---

UPDATE

The problem you are running into is that you have both options in the @XmlElements annotation mapped to the same element content. For unmarshalling JAXB will treat the element based on the first @XmlElement with that name. In the case below it will always treat it as a String, it you reversed the order it would always treat it as an Integer.

@XmlElements({
    @XmlElement(name="content",type=String.class),
    @XmlElement(name="content",type=Integer.class),
})
protected Object content;

The proper usage is to have them mapped to different elements such as

@XmlElements({
    @XmlElement(name="FOO",type=String.class),
    @XmlElement(name="BAR",type=Integer.class),
})
protected Object content;