XML Declaration Tag using SimpleXML

Question

I'm starting to use the Simple XML framework with annotations (link) for Java, but I don't get, how to prelude the XML declaration tag <?xml version="1.0" encoding="UTF-8" ?> in the XML file. So my question is: How do I get the XML declaration as first tag?

package simplexml;

import org.simpleframework.xml.Attribute;
import org.simpleframework.xml.Element;
import org.simpleframework.xml.Root;

@Root
public class Example {

    @Element
    private String text;

    @Attribute
    private int index;

    public Example(String text, int index) {
        this.text = text;
        this.index = index;
    }

    public String getMessage() {
        return text;
    }

    public int getId() {
        return index;
    }
}

Test:

public static void main(String[] args) {
        Serializer serializer = new Persister();
        Example example = new Example("Example message", 123);
        File result = new File("example.xml");

        try {
            serializer.write(example, result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

Produces:

<example index="123">
   <text>Example message</text>
</example>

What I'd like to have:

<?xml version="1.0" encoding="UTF-8" ?>
<example index="123">
   <text>Example message</text>
</example>

Thanks! Also, where could I look such things up?

Answer 1

I use Spring for Android to send XML requests, and was facing the same problem. Here's the code to get it work based on @implicit_knowledge's solution in case anyone needs it.

RestTemplate restTemplate = new RestTemplate();             
restTemplate.getMessageConverters().add(new StringHttpMessageConverter());              
Serializer serializer = new Persister(new Format("<?xml version=\"1.0\" encoding= \"UTF-8\" ?>"));
restTemplate.getMessageConverters().add(new SimpleXmlHttpMessageConverter(serializer));
restTemplate.postForObject(URL, udata, String.class);