/** * Licensed under the Artistic License; you may not use this file * except in compliance with the License. * You may obtain a copy of the License at * *      http://displaytag.sourceforge.net/license.html * * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */package org.displaytag.util;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import org.apache.commons.collections.IteratorUtils;/** * Utility methods for collection handling. * @author Fabrizio Giustina * @version $Revision: 1081 $ ($Author: fgiust $) */public final class CollectionUtil{    /**     * Don't instantiate a CollectionUtil.     */    private CollectionUtil()    {        // unused    }    /**     * Create a list of objects taken from the given iterator and crop the resulting list according to the startIndex     * and numberOfItems parameters.     * @param iterator Iterator     * @param startIndex int starting index     * @param numberOfItems int number of items to keep in the list     * @return List with values taken from the given object, cropped according to startIndex and numberOfItems     * parameters     */    private static List getSubList(Iterator iterator, int startIndex, int numberOfItems)    {        List croppedList = new ArrayList(numberOfItems);        int skippedRecordCount = 0;        int copiedRecordCount = 0;        while (iterator.hasNext())        {            Object object = iterator.next();            if (++skippedRecordCount <= startIndex)            {                continue;            }            croppedList.add(object);            if ((numberOfItems != 0) && (++copiedRecordCount >= numberOfItems))            {                break;            }        }        return croppedList;    }    /**     * create an iterator on a given object (Collection, Enumeration, array, single Object) and crop the resulting list     * according to the startIndex and numberOfItems parameters.     * @param iterableObject Collection, Enumeration or array to crop     * @param startIndex int starting index     * @param numberOfItems int number of items to keep in the list     * @return List with values taken from the given object, cropped according the startIndex and numberOfItems     * parameters     */    public static List getListFromObject(Object iterableObject, int startIndex, int numberOfItems)    {        if (iterableObject instanceof List)        {            // easier, use sublist            List list = ((List) iterableObject);            // check for partial lists            int lastRecordExclusive = numberOfItems <= 0 ? list.size() : startIndex + numberOfItems;            if (lastRecordExclusive > list.size())            {                lastRecordExclusive = list.size();            }            if (startIndex < list.size())            {                return list.subList(startIndex, lastRecordExclusive);            }        }        // use an iterator        Iterator iterator = IteratorUtils.getIterator(iterableObject);        return getSubList(iterator, startIndex, numberOfItems);    }}