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
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<String, Object> map, String key, Object value) {
082 Object oldValue = map.get(key);
083 if (oldValue != null) {
084 List<Object> list;
085 if (oldValue instanceof List) {
086 list = (List<Object>)oldValue;
087 } else {
088 list = new ArrayList<Object>();
089 list.add(oldValue);
090 // replace old entry with list
091 map.remove(key);
092 map.put(key, list);
093 }
094 list.add(value);
095 } else {
096 map.put(key, value);
097 }
098 }
099
100 public static <T> Set<T> createSetContaining(T... contents) {
101 Set<T> contentsAsSet = new HashSet<T>();
102 contentsAsSet.addAll(Arrays.asList(contents));
103 return contentsAsSet;
104 }
105
106 public static String collectionAsCommaDelimitedString(String[] col) {
107 if (col == null || col.length == 0) {
108 return "";
109 }
110 return collectionAsCommaDelimitedString(Arrays.asList(col));
111 }
112
113 public static String collectionAsCommaDelimitedString(Collection<?> col) {
114 if (col == null || col.isEmpty()) {
115 return "";
116 }
117
118 StringBuilder sb = new StringBuilder();
119 Iterator<?> it = col.iterator();
120 while (it.hasNext()) {
121 sb.append(it.next().toString());
122 if (it.hasNext()) {
123 sb.append(",");
124 }
125 }
126
127 return sb.toString();
128 }
129 }