Question

I’m using JAXB(xjc version 2.2.4-2) to generate Java classes from a XML Schema. The XML types that map to a Java primitive datatype don’t add:

@XmlElement(required = true)

For example when using:

<element name="userId" type="long"/>
<element name="userName" type="string"/> 

will result in:

//no annotation added here
protected long userId;
@XmlElement(required = true)
protected String userName;

Does anyone have an explanation why this happens?

Does any of this have to do with options that you can set with xjc?

Answer 1

You don’t need an annotation to show that a property of Java type long is required as this is implicit from the fact that primitive values can’t be null. A non-nillable required element of type xs:long maps to Java long, an optional or nillable one maps to java.lang.Long (which permits null, representing absent or xsi:nil as appropriate).

An element that is both optional and nillable (odd, but allowed by XML Schema) would map to a JAXBElement<Long> to distinguish between absent (a null JAXBElement) and nil (a non-null JAXBElement whose isNil() returns true).