001    // Copyright 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.web;
016    
017    import java.util.ArrayList;
018    import java.util.Collections;
019    import java.util.Enumeration;
020    import java.util.List;
021    
022    import org.apache.hivemind.util.Defense;
023    
024    /**
025     * @author Howard M. Lewis Ship
026     * @since 4.0
027     */
028    public final class WebUtils
029    {
030        /* defeat instantiation */
031        private WebUtils() { }
032        
033        /**
034         * Converts an Enumeration of Strings into an unmodifiable List of Strings, sorted into
035         * ascending order.
036         */
037    
038        public static List toSortedList(Enumeration e)
039        {
040            Defense.notNull(e, "e");
041    
042            List list = new ArrayList();
043            while (e.hasMoreElements())
044                list.add(e.nextElement());
045    
046            if (list.isEmpty())
047                return Collections.EMPTY_LIST;
048    
049            Collections.sort(list);
050    
051            return Collections.unmodifiableList(list);
052        }
053    
054    }