001/**
002 * Copyright 2005-2016 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.krad.util;
017
018import java.util.Iterator;
019
020import org.apache.commons.collections.IteratorUtils;
021
022/**
023 * This class provides utility methods to support the operation of transactional services
024 */
025public final class TransactionalServiceUtils {
026        
027        private TransactionalServiceUtils() {
028                throw new UnsupportedOperationException("do not call");
029        }
030    /**
031     * Copys iterators so that they may be used outside of this class.  Often, the DAO may
032     * return iterators that may not be used outside of this class because the transaction/
033     * connection may be automatically closed by Spring.
034     * 
035     * This method copies all of the elements in the OJB backed iterators into list-based iterators
036     * by placing the returned BOs into a list
037     * 
038     * @param iter an OJB backed iterator to copy
039     * @return an Iterator that may be used outside of this class
040     */
041    public static <E> Iterator<E> copyToExternallyUsuableIterator(Iterator<E> iter) {
042        return IteratorUtils.toList(iter).iterator();
043    }
044    
045    /**
046     * Returns the first element and exhausts an iterator
047     * 
048     * @param <E> the type of elements in the iterator
049     * @param iterator the iterator to exhaust
050     * @return the first element of the iterator; null if the iterator's empty
051     */
052    public static <E> E retrieveFirstAndExhaustIterator(Iterator<E> iterator) {
053        E returnVal = null;
054        if (iterator.hasNext()) {
055            returnVal = iterator.next();
056        }
057        exhaustIterator(iterator);
058        return returnVal;
059    }
060    
061    /**
062     * Exhausts (i.e. complete iterates through) an iterator
063     * 
064     * @param iterator
065     */
066    public static void exhaustIterator(Iterator<?> iterator) {
067        while (iterator.hasNext()) {
068            iterator.next();
069        }
070    }
071}