XML Schema type that generates Java primitive type using JAXB doesn't add required to it

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).

Answer 2

If you don't mind a BigInteger in your java class you could use type="integer" or type="positiveInteger" (negative userId?). Your validation will work this way at a certain cost.

Another option would be to use jaxb custom bindings. Your element could be:

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

and your have to create an extra binding file e.g.

<jxb:bindings version="1.0" 
  xmlns:jxb="http://java.sun.com/xml/ns/jaxb" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc" 
  jxb:extensionBindingPrefixes="xjc">
<jxb:bindings schemaLocation="my.xsd" node="//xs:element[@name='UserType']//xs:element[@name='userId']">
 <jxb:property>
  <jxb:baseType name="java.lang.Long" />
 </jxb:property>
</jxb:bindings>
</jxb:bindings>

Now you can call xjc like: xjc my.xsd -b my.xjb

This results in:

@XmlElement(required = true, type = Long.class) protected Integer userId;