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package javax.xml.bind.annotation;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static java.lang.annotation.ElementType.TYPE;

/**
 * Maps a class or an enum type to an XML element.
 *
 * <p> <b>Usage</b> </p>
 * <p>
 * The &#64;XmlRootElement annotation can be used with the following program
 * elements: 
 * <ul> 
 *   <li> a top level class </li>
 *   <li> an enum type </li>
 * </ul>
 *
 * <p>See "Package Specification" in javax.xml.bind.package javadoc for
 * additional common information.</p>
 * 
 * <p>
 * When a top level class or an enum type is annotated with the 
 * &#64;XmlRootElement annotation, then its value is represented 
 * as XML element in an XML document.
 *
 * <p> This annotation can be used with the following annotations:
 * {@link XmlType}, {@link XmlEnum}, {@link XmlAccessorType}, 
 * {@link XmlAccessorOrder}.
 * </p>

 * <p>
 * <b>Example 1: </b> Associate an element with XML Schema type
 * <pre>
 *     // Example: Code fragment
 *     &#64;XmlRootElement
 *     class Point {
 *        int x;
 *        int y;
 *        Point(int _x,int _y) {x=_x;y=_y;}
 *     }
 * </pre>
 *
 * <pre>
 *     //Example: Code fragment corresponding to XML output
 *     marshal( new Point(3,5), System.out);
 * </pre>
 *
 * <pre>
 *     &lt;!-- Example: XML output --&gt;
 *     &lt;point&gt;
 *       &lt;x&gt; 3 &lt;/x&gt;
 *       &lt;y&gt; 5 &lt;/y&gt;
 *     &lt;/point&gt;
 * </pre>
 *
 * 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.
 *
 * <pre>
 *     &lt;!-- Example: XML schema definition --&gt;
 *     &lt;xs:element name="point" type="point"/&gt;
 *     &lt;xs:complexType name="point"&gt;
 *       &lt;xs:sequence&gt;
 *         &lt;xs:element name="x" type="xs:int"/&gt;
 *         &lt;xs:element name="y" type="xs:int"/&gt;
 *       &lt;/xs:sequence&gt;
 *     &lt;/xs:complexType&gt;
 * </pre>
 *
 * <p>
 *
 * <b>Example 2: Orthogonality to type inheritance </b>
 * 
 * <p>
 * An element declaration annotated on a type is not inherited by its
 * derived types. The following example shows this.
 * <pre>
 *     // Example: Code fragment
 *     &#64;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 );
 *
 *     &lt;!-- Example: XML output --&gt;
 *     &lt;!-- The element name is point3D not point --&gt;
 *     &lt;point3D&gt;
 *       &lt;x&gt;3&lt;/x&gt;
 *       &lt;y&gt;5&lt;/y&gt;
 *       &lt;z&gt;0&lt;/z&gt;
 *     &lt;/point3D&gt;
 *
 *     &lt;!-- Example: XML schema definition --&gt;
 *     &lt;xs:element name="point3D" type="point3D"/&gt;
 *     &lt;xs:complexType name="point3D"&gt;
 *       &lt;xs:complexContent&gt;
 *         &lt;xs:extension base="point"&gt;
 *           &lt;xs:sequence&gt;
 *             &lt;xs:element name="z" type="xs:int"/&gt;
 *           &lt;/xs:sequence&gt;
 *         &lt;/xs:extension&gt;
 *       &lt;/xs:complexContent&gt;
 *     &lt;/xs:complexType&gt;
 * </pre>
 *
 * <b>Example 3: </b> Associate a global element with XML Schema type
 * to which the class is mapped.
 * <pre>
 *     //Example: Code fragment
 *     &#64;XmlRootElement(name="PriceElement")
 *     public class USPrice {
 *         &#64;XmlElement
 *         public java.math.BigDecimal price;
 *     }
 *
 *     &lt;!-- Example: XML schema definition --&gt;
 *     &lt;xs:element name="PriceElement" type="USPrice"/&gt;
 *     &lt;xs:complexType name="USPrice"&gt;
 *       &lt;xs:sequence&gt;
 *         &lt;xs:element name="price" type="xs:decimal"/&gt;
 *       &lt;/sequence&gt;
 *     &lt;/xs:complexType&gt;
 * </pre>
 *
 * @author Sekhar Vajjhala, Sun Microsystems, Inc.
 * @since 1.6, JAXB 2.0
 */
@Retention(RUNTIME)
@Target({TYPE})
public @interface XmlRootElement {
    /**
     * namespace name of the XML element.
     * <p>
     * If the value is "##default", then the XML namespace name is derived
     * from the package of the class ( {@link XmlSchema} ). If the
     * package is unnamed, then the XML namespace is the default empty
     * namespace.
     */
    String namespace() default "##default";

    /**
     * local name of the XML element.
     * <p>
     * If the value is "##default", then the name is derived from the
     * class name. 
     *
     */
    String name() default "##default";

}
