package org.kuali.rice.core.util.jaxb;

 import javax.xml.bind.annotation.adapters.XmlAdapter;

 import java.util.Arrays;

 import java.util.Collection;

 import java.util.Collections;

 /**

  * Handles JAXB mapping that ensures that any Collection created from unmarshalled XML will be an immutable

  * non-null Collection reference..

  */

 public class ImmutableCollectionAdapter extends XmlAdapter<Object[], Collection<?>> {

     /**

      * <p>Returns an immutable Collection when a Collection is meant to be unmarshalled from XML.  This is done to ensure service

      * contracts, which are to return immutable objects, also return immutable Collections when an XML sequence is returned

      * via a remote SOAP call.</p>

      *

      * <p>If the XML being unmarshalled, represented by the objects parameter, is empty or null then an empty List

      * is returned.</p>

      *

      * @param objects an array of Objects collected from XML to be transformed into an immutable Collection

      * @return An immutable Collection

      * @throws Exception

      */

     @Override

     public Collection<?> unmarshal(Object[] objects) throws Exception {

         return Collections.unmodifiableCollection(Arrays.asList(objects));

     }

     /**

      * Creates an array of Object[] from a passed in Collection for JAXB marshalling. There is no requirement of what kind of

      * Collection is used when marshalling to XML.

      *

      * @param objects

      * @return An Object[] containing the same contents as the passed in Collection.

      * @throws Exception

      */

     @Override

     public Object[] marshal(Collection<?> objects) throws Exception {

         return objects.toArray();

     }

 }