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: 36321 $ 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 public static Integer size(Object value) { 044 if (value != null) { 045 if (value instanceof Collection) { 046 Collection collection = (Collection)value; 047 return collection.size(); 048 } else if (value instanceof Map) { 049 Map map = (Map)value; 050 return map.size(); 051 } else if (value instanceof Object[]) { 052 Object[] array = (Object[])value; 053 return array.length; 054 } else if (value.getClass().isArray()) { 055 return Array.getLength(value); 056 } else if (value instanceof NodeList) { 057 NodeList nodeList = (NodeList)value; 058 return nodeList.getLength(); 059 } 060 } 061 return null; 062 } 063 064 /** 065 * Sets the value of the entry in the map for the given key, though if the 066 * map already contains a value for the given key then the value is appended 067 * to a list of values. 068 * 069 * @param map the map to add the entry to 070 * @param key the key in the map 071 * @param value the value to put in the map 072 */ 073 public static void appendValue(Map map, Object key, Object value) { 074 075 Object oldValue = map.get(key); 076 if (oldValue != null) { 077 List list; 078 if (oldValue instanceof List) { 079 list = (List)oldValue; 080 } else { 081 list = new ArrayList(); 082 list.add(oldValue); 083 } 084 list.add(value); 085 } else { 086 map.put(key, value); 087 } 088 } 089 }