Question

I have a Java bean ala

@XmlRootElement public class Bean {
    @XmlElementWrapper(name = "ints") @XmlElement(name = "int")
    int[] values;

    // constructors, getters, setters, etc...
}

JAXB is producing XML like

<bean>
    <ints>
        <int>12</int>
        <int>34</int>
        <int>56</int>
    </ints>
</bean>

I would like the array indices to be included on the <int> tags as array position conveys important value. Preferably as attributes like

<bean>
    <ints>
        <int id='0'>12</int>
        <int id='1'>34</int>
        <int id='2'>56</int>
    </ints>
</bean>

Is there a way to do this?

Answer 1

The order of XML elements does carry information. A sequence of elements has an explicit order, so adding an array index would be redundant, unless you plan on skipping indexes, or having them out-of-order.

Because of this reasoning, JAXB provides no way of doing what you’re asking automatically. If you still want to do this, you’ll need to wrap your values in a class which incorporates the index values as an @XmlAttribute value:

@XmlRootElement 
public class Bean {
    @XmlElementWrapper(name = "ints")
    @XmlElement(name = "int")
    MyInt[] values;

    // constructors, getters, setters, etc...
}

public class MyInt {
   @XmlAttribute(name="id")
   int id;

   @XmlValue
   int value;
}

It would up to you to make sure the id fields are populated correctly.