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6.2.7.3
Class Fields as Attributes: XmlAttribute
Provided that XML lets you represent a data item as a single value, there is no cut-and-dried rule for deciding between using an element or an attribute. (If you look for guidance, the schema describing the XML Schema language itself, making judicious use of both, is a good example.) JAXB, of course, has to be told when to make a field into an XML attribute.
The annotation for creating an XML attribute is XmlAttribute.
Its elements correspond to what can be defined in an XML schema:
namedefines the namestring for the attribute, the default being the class field's name.namespacespecifies the XML target namespace to be used for the attribute's name.- A "true" value of
requiredis the same as using the XML Schema definition's attributeuse="required".
default="value", then the
simple answer is: "Do it yourself." Just write the getter so that it
returns the default value if the field's value is null.
It's possible to annotate a static final field with XmlAttribute.
This has the same effect as an XML Schema definition where the
attribute element's attribute fixed is set to that
value.
@XmlAttribute final static int answer = 42;
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