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copied!<p>To tie together what others have already stated or hinted at, the rules by which JAXB XJC decides whether or not to put the <code>@XmlRootElement</code> annotation on a generated class are non trivial (<a href="http://web.archive.org/web/20160117210900/https://community.oracle.com/blogs/kohsuke/2006/03/03/why-does-jaxb-put-xmlrootelement-sometimes-not-always" rel="noreferrer">see this article</a>).</p> <p><code>@XmlRootElement</code> exists because the JAXB runtime requires certain information in order to marshal/unmarshal a given object, specifically the XML element name and namespace. You can't just pass any old object to the Marshaller. <code>@XmlRootElement</code> provides this information.</p> <p>The annotation is just a convenience, however - JAXB does not require it. The alternative to is to use <code>JAXBElement</code> wrapper objects, which provide the same information as <code>@XmlRootElement</code>, but in the form of an object, rather than an annotation. </p> <p>However, <code>JAXBElement</code> objects are awkward to construct, since you need to know the XML element name and namespace, which business logic usually doesn't. </p> <p>Thankfully, when XJC generates a class model, it also generates a class called <code>ObjectFactory</code>. This is partly there for backwards compatibility with JAXB v1, but it's also there as a place for XJC to put generated factory methods which create <code>JAXBElement</code> wrappers around your own objects. It handles the XML name and namespace for you, so you don't need to worry about it. You just need to look through the <code>ObjectFactory</code> methods (and for large schema, there can be hundreds of them) to find the one you need.</p>

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