001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.util;
018
019 import java.lang.reflect.Array;
020 import java.util.ArrayList;
021 import java.util.Collection;
022 import java.util.List;
023 import java.util.Map;
024
025 import org.w3c.dom.NodeList;
026
027 /**
028 * A number of helper methods for working with collections
029 *
030 * @version $Revision: 723967 $
031 */
032 public final class CollectionHelper {
033
034 /**
035 * Utility classes should not have a public constructor.
036 */
037 private CollectionHelper() {
038 }
039
040 /**
041 * Returns the size of the collection if it can be determined to be a collection
042 *
043 * @param value the collection
044 * @return the size, or <tt>null</tt> if not a collection
045 */
046 public static Integer size(Object value) {
047 if (value != null) {
048 if (value instanceof Collection) {
049 Collection collection = (Collection)value;
050 return collection.size();
051 } else if (value instanceof Map) {
052 Map map = (Map)value;
053 return map.size();
054 } else if (value instanceof Object[]) {
055 Object[] array = (Object[])value;
056 return array.length;
057 } else if (value.getClass().isArray()) {
058 return Array.getLength(value);
059 } else if (value instanceof NodeList) {
060 NodeList nodeList = (NodeList)value;
061 return nodeList.getLength();
062 }
063 }
064 return null;
065 }
066
067 /**
068 * Sets the value of the entry in the map for the given key, though if the
069 * map already contains a value for the given key then the value is appended
070 * to a list of values.
071 *
072 * @param map the map to add the entry to
073 * @param key the key in the map
074 * @param value the value to put in the map
075 */
076 public static void appendValue(Map map, Object key, Object value) {
077 Object oldValue = map.get(key);
078 if (oldValue != null) {
079 List list;
080 if (oldValue instanceof List) {
081 list = (List)oldValue;
082 } else {
083 list = new ArrayList();
084 list.add(oldValue);
085 }
086 list.add(value);
087 } else {
088 map.put(key, value);
089 }
090 }
091
092 /**
093 * Filters the given list to skip instanceof filter objects.
094 *
095 * @param list the list
096 * @param filters objects to skip
097 * @return a new list without the filtered objects
098 */
099 public static List filterList(List list, Object... filters) {
100 List answer = new ArrayList();
101 for (Object o : list) {
102 for (Object filter : filters) {
103 if (!o.getClass().isInstance(filter)) {
104 answer.add(o);
105 }
106 }
107 }
108 return answer;
109 }
110 }