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.Arrays;
022 import java.util.Collection;
023 import java.util.HashSet;
024 import java.util.Iterator;
025 import java.util.List;
026 import java.util.Map;
027 import java.util.Set;
028
029 import org.w3c.dom.NodeList;
030
031 /**
032 * A number of helper methods for working with collections
033 *
034 * @version $Revision: 785479 $
035 */
036 public final class CollectionHelper {
037
038 /**
039 * Utility classes should not have a public constructor.
040 */
041 private CollectionHelper() {
042 }
043
044 /**
045 * Returns the size of the collection if it can be determined to be a collection
046 *
047 * @param value the collection
048 * @return the size, or <tt>null</tt> if not a collection
049 */
050 public static Integer size(Object value) {
051 if (value != null) {
052 if (value instanceof Collection) {
053 Collection collection = (Collection)value;
054 return collection.size();
055 } else if (value instanceof Map) {
056 Map map = (Map)value;
057 return map.size();
058 } else if (value instanceof Object[]) {
059 Object[] array = (Object[])value;
060 return array.length;
061 } else if (value.getClass().isArray()) {
062 return Array.getLength(value);
063 } else if (value instanceof NodeList) {
064 NodeList nodeList = (NodeList)value;
065 return nodeList.getLength();
066 }
067 }
068 return null;
069 }
070
071 /**
072 * Sets the value of the entry in the map for the given key, though if the
073 * map already contains a value for the given key then the value is appended
074 * to a list of values.
075 *
076 * @param map the map to add the entry to
077 * @param key the key in the map
078 * @param value the value to put in the map
079 */
080 @SuppressWarnings("unchecked")
081 public static void appendValue(Map map, Object key, Object value) {
082 Object oldValue = map.get(key);
083 if (oldValue != null) {
084 List list;
085 if (oldValue instanceof List) {
086 list = (List)oldValue;
087 } else {
088 list = new ArrayList();
089 list.add(oldValue);
090 }
091 list.add(value);
092 } else {
093 map.put(key, value);
094 }
095 }
096
097 /**
098 * Filters the given list to skip instanceof filter objects.
099 *
100 * @param list the list
101 * @param filters objects to skip
102 * @return a new list without the filtered objects
103 */
104 @SuppressWarnings("unchecked")
105 public static List filterList(List list, Object... filters) {
106 List answer = new ArrayList();
107 for (Object o : list) {
108 for (Object filter : filters) {
109 if (!o.getClass().isInstance(filter)) {
110 answer.add(o);
111 }
112 }
113 }
114 return answer;
115 }
116
117 public static <T> Set<T> createSetContaining(T... contents) {
118 Set<T> contentsAsSet = new HashSet<T>();
119 contentsAsSet.addAll(Arrays.asList(contents));
120 return contentsAsSet;
121 }
122
123 public static String collectionAsCommaDelimitedString(String[] col) {
124 if (col == null || col.length == 0) {
125 return "";
126 }
127 return collectionAsCommaDelimitedString(Arrays.asList(col));
128 }
129
130 public static String collectionAsCommaDelimitedString(Collection col) {
131 if (col == null || col.isEmpty()) {
132 return "";
133 }
134
135 StringBuilder sb = new StringBuilder();
136 Iterator it = col.iterator();
137 while (it.hasNext()) {
138 sb.append(it.next());
139 if (it.hasNext()) {
140 sb.append(",");
141 }
142 }
143
144 return sb.toString();
145 }
146
147 }