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.Iterator; 024 import java.util.List; 025 import java.util.Map; 026 027 import org.w3c.dom.NodeList; 028 029 /** 030 * A number of helper methods for working with collections 031 * 032 * @version $Revision: 747062 $ 033 */ 034 public final class CollectionHelper { 035 036 /** 037 * Utility classes should not have a public constructor. 038 */ 039 private CollectionHelper() { 040 } 041 042 /** 043 * Returns the size of the collection if it can be determined to be a collection 044 * 045 * @param value the collection 046 * @return the size, or <tt>null</tt> if not a collection 047 */ 048 public static Integer size(Object value) { 049 if (value != null) { 050 if (value instanceof Collection) { 051 Collection collection = (Collection)value; 052 return collection.size(); 053 } else if (value instanceof Map) { 054 Map map = (Map)value; 055 return map.size(); 056 } else if (value instanceof Object[]) { 057 Object[] array = (Object[])value; 058 return array.length; 059 } else if (value.getClass().isArray()) { 060 return Array.getLength(value); 061 } else if (value instanceof NodeList) { 062 NodeList nodeList = (NodeList)value; 063 return nodeList.getLength(); 064 } 065 } 066 return null; 067 } 068 069 /** 070 * Sets the value of the entry in the map for the given key, though if the 071 * map already contains a value for the given key then the value is appended 072 * to a list of values. 073 * 074 * @param map the map to add the entry to 075 * @param key the key in the map 076 * @param value the value to put in the map 077 */ 078 @SuppressWarnings("unchecked") 079 public static void appendValue(Map map, Object key, Object value) { 080 Object oldValue = map.get(key); 081 if (oldValue != null) { 082 List list; 083 if (oldValue instanceof List) { 084 list = (List)oldValue; 085 } else { 086 list = new ArrayList(); 087 list.add(oldValue); 088 } 089 list.add(value); 090 } else { 091 map.put(key, value); 092 } 093 } 094 095 /** 096 * Filters the given list to skip instanceof filter objects. 097 * 098 * @param list the list 099 * @param filters objects to skip 100 * @return a new list without the filtered objects 101 */ 102 @SuppressWarnings("unchecked") 103 public static List filterList(List list, Object... filters) { 104 List answer = new ArrayList(); 105 for (Object o : list) { 106 for (Object filter : filters) { 107 if (!o.getClass().isInstance(filter)) { 108 answer.add(o); 109 } 110 } 111 } 112 return answer; 113 } 114 115 public static String collectionAsCommaDelimitedString(String[] col) { 116 if (col == null || col.length == 0) { 117 return ""; 118 } 119 return collectionAsCommaDelimitedString(Arrays.asList(col)); 120 } 121 122 public static String collectionAsCommaDelimitedString(Collection col) { 123 if (col == null || col.isEmpty()) { 124 return ""; 125 } 126 127 StringBuilder sb = new StringBuilder(); 128 Iterator it = col.iterator(); 129 while (it.hasNext()) { 130 sb.append(it.next()); 131 if (it.hasNext()) { 132 sb.append(","); 133 } 134 } 135 136 return sb.toString(); 137 } 138 139 }