Module java.xml.bind

Package javax.xml.bind.annotation

Annotation Type XmlRootElement

@Retention(RUNTIME)
@Target(TYPE)
public @interface XmlRootElement

Maps a class or an enum type to an XML element.

Usage

The @XmlRootElement annotation can be used with the following program elements:

• a top level class
• an enum type

See "Package Specification" in javax.xml.bind.package javadoc for additional common information.

When a top level class or an enum type is annotated with the @XmlRootElement annotation, then its value is represented as XML element in an XML document.

This annotation can be used with the following annotations: XmlType, XmlEnum, XmlAccessorType, XmlAccessorOrder.

Example 1: Associate an element with XML Schema type

     // Example: Code fragment
     @XmlRootElement
     class Point {
        int x;
        int y;
        Point(int _x,int _y) {x=_x;y=_y;}
     }
 

     //Example: Code fragment corresponding to XML output
     marshal( new Point(3,5), System.out);
 

     <!-- Example: XML output -->
     <point>
       <x> 3 </x>
       <y> 5 </y>
     </point>
 

The annotation causes an global element declaration to be produced in the schema. The global element declaration is associated with the XML schema type to which the class is mapped.

     <!-- Example: XML schema definition -->
     <xs:element name="point" type="point"/>
     <xs:complexType name="point">
       <xs:sequence>
         <xs:element name="x" type="xs:int"/>
         <xs:element name="y" type="xs:int"/>
       </xs:sequence>
     </xs:complexType>
 

Example 2: Orthogonality to type inheritance

An element declaration annotated on a type is not inherited by its derived types. The following example shows this.

     // Example: Code fragment
     @XmlRootElement
     class Point3D extends Point {
         int z;
         Point3D(int _x,int _y,int _z) {super(_x,_y);z=_z;}
     }

     //Example: Code fragment corresponding to XML output *
     marshal( new Point3D(3,5,0), System.out );
 

     <!-- Example: XML output -->
     <!-- The element name is point3D not point -->
     <point3D>
       <x>3</x>
       <y>5</y>
       <z>0</z>
     </point3D>

     <!-- Example: XML schema definition -->
     <xs:element name="point3D" type="point3D"/>
     <xs:complexType name="point3D">
       <xs:complexContent>
         <xs:extension base="point">
           <xs:sequence>
             <xs:element name="z" type="xs:int"/>
           </xs:sequence>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
 

Example 3: Associate a global element with XML Schema type to which the class is mapped.

     //Example: Code fragment
     @XmlRootElement(name="PriceElement")
     public class USPrice {
         @XmlElement
         public java.math.BigDecimal price;
     }
 

     <!-- Example: XML schema definition -->
     <xs:element name="PriceElement" type="USPrice"/>
     <xs:complexType name="USPrice">
       <xs:sequence>
         <xs:element name="price" type="xs:decimal"/>
       </sequence>
     </xs:complexType>
 

Since:

1.6, JAXB 2.0

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
String	name	local name of the XML element.
String	namespace	namespace name of the XML element.

Element Detail

namespace

String namespace

namespace name of the XML element.

If the value is "##default", then the XML namespace name is derived from the package of the class ( XmlSchema ). If the package is unnamed, then the XML namespace is the default empty namespace.

Default:

"##default"

name

String name

local name of the XML element.

If the value is "##default", then the name is derived from the class name.

Default:

"##default"