/*

  * Copyright 2007 The Kuali Foundation

  * 

  * Licensed under the Educational Community License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  * http://www.opensource.org/licenses/ecl2.php

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.kuali.rice.kns.util;

 import java.util.Iterator;

 import org.apache.commons.collections.IteratorUtils;

 /**

  * This class provides utility methods to support the operation of transactional services

  */

 public class TransactionalServiceUtils {

     /**

      * Copys iterators so that they may be used outside of this class.  Often, the DAO may

      * return iterators that may not be used outside of this class because the transaction/

      * connection may be automatically closed by Spring.

      * 

      * This method copies all of the elements in the OJB backed iterators into list-based iterators

      * by placing the returned BOs into a list

      * 

      * @param iter an OJB backed iterator to copy

      * @return an Iterator that may be used outside of this class

      */

     public static <E> Iterator<E> copyToExternallyUsuableIterator(Iterator<E> iter) {

         return IteratorUtils.toList(iter).iterator();

     }

     /**

      * Returns the first element and exhausts an iterator

      * 

      * @param <E> the type of elements in the iterator

      * @param iterator the iterator to exhaust

      * @return the first element of the iterator; null if the iterator's empty

      */

     public static <E> E retrieveFirstAndExhaustIterator(Iterator<E> iterator) {

         E returnVal = null;

         if (iterator.hasNext()) {

             returnVal = iterator.next();

         }

         exhaustIterator(iterator);

         return returnVal;

     }

     /**

      * Exhausts (i.e. complete iterates through) an iterator

      * 

      * @param iterator

      */

     public static void exhaustIterator(Iterator<?> iterator) {

         while (iterator.hasNext()) {

             iterator.next();

         }

     }

 }