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This annotation serves as a "catch-all" property while unmarshalling xml content into a instance of a JAXB annotated class. It typically annotates a multi-valued JavaBean property, but it can occur on single value JavaBean property. During unmarshalling, each xml element that does not match a static @XmlElement or @XmlElementRef annotation for the other JavaBean properties on the class, is added to this "catch-all" property.

Usages:

 @XmlAnyElement
 public 
Element [] others;
 // Collection of 
Element  or JAXB elements.
 @XmlAnyElement(lax="true")
 public 
Object [] others;
 @XmlAnyElement
 private List<
Element > nodes;
 @XmlAnyElement
 private 
Element  node;
 

Restriction usage constraints

This annotation is mutually exclusive with XmlElement , XmlAttribute , XmlValue , XmlElements , XmlID , and XmlIDREF .

There can be only one XmlAnyElement annotated JavaBean property in a class and its super classes.

Relationship to other annotations

This annotation can be used with XmlJavaTypeAdapter , so that users can map their own data structure to DOM, which in turn can be composed into XML.

This annotation can be used with XmlMixed like this:

 // List of java.lang.String or DOM nodes.
 @XmlAnyElement @XmlMixed
 List<Object> others;
 

Schema To Java example

 <xs:complexType name="foo">
 <xs:sequence>
 <xs:element name="a" type="xs:int" />
 <xs:element name="b" type="xs:int" />
 <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
 </xs:sequence>
 </xs:complexType>
 

 class Foo {
 int a;
 int b;
 @
XmlAnyElement List<Element> any;
 }
 

 <foo xmlns:e="extra">
 <a>1</a>
 <e:other />  // this will be bound to DOM, because unmarshalling is orderless
 <b>3</b>
 <e:other />
 <c>5</c>     // this will be bound to DOM, because the annotation doesn't remember namespaces.
 </foo>
 

 <xs:complexType name="bar">
 <xs:complexContent>
 <xs:extension base="foo">
 <xs:sequence>
 <xs:element name="c" type="xs:int" />
 <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
 </xs:sequence>
 </xs:extension>
 </xs:complexType>
 

 class Bar extends Foo {
 int c;
 // Foo.getAny() also represents wildcard content for type definition bar.
 }
 

 <bar xmlns:e="extra">
 <a>1</a>
 <e:other />  // this will be bound to DOM, because unmarshalling is orderless
 <b>3</b>
 <e:other />
 <c>5</c>     // this now goes to Bar.c
 <e:other />  // this will go to Foo.any
 </bar>
 

Using XmlAnyElement with XmlElementRef

The XmlAnyElement annotation can be used with XmlElementRef s to designate additional elements that can participate in the content tree.

The following schema would produce the following Java class:

 <xs:complexType name="foo">
 <xs:choice maxOccurs="unbounded" minOccurs="0">
 <xs:element name="a" type="xs:int" />
 <xs:element name="b" type="xs:int" />
 <xs:any namespace="##other" processContents="lax" />
 </xs:choice>
 </xs:complexType>
 

 class Foo {
 @
XmlAnyElement (lax="true")
 @
XmlElementRefs ({
 @
XmlElementRef (name="a", type="JAXBElement.class")
 @
XmlElementRef (name="b", type="JAXBElement.class")
 })
List <
Object > others;
 }
 @XmlRegistry
 class ObjectFactory {
 ...
 @XmlElementDecl(name = "a", namespace = "", scope = Foo.class)
JAXBElement <Integer> createFooA( Integer i ) { ... }
 @XmlElementDecl(name = "b", namespace = "", scope = Foo.class)
JAXBElement <Integer> createFooB( Integer i ) { ... }
 

 <foo xmlns:e="extra">
 <a>1</a>     // this will unmarshal to a 
<a href="../JAXBElement.java.htm"><B>JAXBElement</B></a>  instance whose value is 1.
 <e:other />  // this will unmarshal to a DOM 
<a href="../../../../../../6.0-JDK-Core/w3c/org/w3c/dom/Element.java.htm"><B>Element</B></a> .
 <b>3</b>     // this will unmarshal to a 
<a href="../JAXBElement.java.htm"><B>JAXBElement</B></a>  instance whose value is 1.
 </foo>
 

W3C XML Schema "lax" wildcard emulation

 @
XmlRootElement class Foo {
 @XmlAnyElement(lax=true)
 public 
Object [] others;
 }
 

 <foo>
 <unknown />
 <foo />
 </foo>
 Foo foo = unmarshal();
 // 1 for 'unknown', another for 'foo'
 assert foo.others.length==2;
 // 'unknown' unmarshals to a DOM element
 assert foo.others[0] instanceof Element;
 // because of lax=true, the 'foo' element eagerly
 // unmarshals to a Foo object.
 assert foo.others[1] instanceof Foo;
 

When false

If false, all the elements that match the property will be unmarshalled to DOM, and the property will only contain DOM elements.

When true

If true, when an element matches a property marked with XmlAnyElement is known to JAXBContext (for example, there's a class with XmlRootElement that has the same tag name, or there's XmlElementDecl that has the same tag name), the unmarshaller will eagerly unmarshal this element to the JAXB object, instead of unmarshalling it to DOM.

When false

If false, all the elements that match the property will be unmarshalled to DOM, and the property will only contain DOM elements.

When true

If true, when an element matches a property marked with XmlAnyElement is known to JAXBContext (for example, there's a class with XmlRootElement that has the same tag name, or there's XmlElementDecl that has the same tag name), the unmarshaller will eagerly unmarshal this element to the JAXB object, instead of unmarshalling it to DOM. Additionally, if the element is unknown but it has a known xsi:type, the unmarshaller eagerly unmarshals the element to a JAXBElement , with the unknown element name and the JAXBElement value is set to an instance of the JAXB mapping of the known xsi:type.

As a result, after the unmarshalling, the property can become heterogeneous; it can have both DOM nodes and some JAXB objects at the same time.

This can be used to emulate the "lax" wildcard semantics of the W3C XML Schema.