svn-gvsig-desktop / tags / v1_1_Build_1007 / applications / appgvSIG / src / com / vividsolutions / jump / util / CollectionUtil.java @ 12478
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1 | 312 | fernando | /*
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2 | * The Unified Mapping Platform (JUMP) is an extensible, interactive GUI
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3 | * for visualizing and manipulating spatial features with geometry and attributes.
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4 | *
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5 | * Copyright (C) 2003 Vivid Solutions
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6 | *
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7 | * This program is free software; you can redistribute it and/or
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8 | * modify it under the terms of the GNU General Public License
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9 | * as published by the Free Software Foundation; either version 2
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10 | * of the License, or (at your option) any later version.
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11 | *
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12 | * This program is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with this program; if not, write to the Free Software
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19 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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20 | *
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21 | * For more information, contact:
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22 | *
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23 | * Vivid Solutions
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24 | * Suite #1A
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25 | * 2328 Government Street
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26 | * Victoria BC V8T 5G5
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27 | * Canada
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28 | *
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29 | * (250)385-6040
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30 | * www.vividsolutions.com
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31 | */
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32 | package com.vividsolutions.jump.util; |
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33 | |||
34 | import java.util.ArrayList; |
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35 | import java.util.Collection; |
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36 | import java.util.Collections; |
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37 | import java.util.HashMap; |
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38 | import java.util.Iterator; |
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39 | import java.util.List; |
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40 | import java.util.Map; |
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41 | import java.util.SortedSet; |
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42 | import java.util.TreeSet; |
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43 | |||
44 | 8765 | jjdelcerro | import com.vividsolutions.jts.util.Assert; |
45 | 312 | fernando | |
46 | 8765 | jjdelcerro | |
47 | 312 | fernando | public class CollectionUtil { |
48 | public CollectionUtil() {
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49 | } |
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50 | |||
51 | /**
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52 | * Returns a List of Lists: all combinations of the elements of the given List.
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53 | * @param maxCombinationSize combinations larger than this value are discarded
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54 | */
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55 | public static List combinations(List original, int maxCombinationSize) { |
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56 | return combinations(original, maxCombinationSize, null); |
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57 | } |
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58 | |||
59 | public static Map inverse(Map map) { |
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60 | Map inverse;
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61 | try {
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62 | inverse = (Map) map.getClass().newInstance();
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63 | } catch (InstantiationException e) { |
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64 | Assert.shouldNeverReachHere(e.toString()); |
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65 | |||
66 | return null; |
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67 | } catch (IllegalAccessException e) { |
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68 | Assert.shouldNeverReachHere(e.toString()); |
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69 | |||
70 | return null; |
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71 | } |
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72 | for (Iterator i = map.keySet().iterator(); i.hasNext();) { |
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73 | Object key = i.next();
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74 | Object value = map.get(key);
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75 | inverse.put(value, key); |
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76 | } |
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77 | |||
78 | return inverse;
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79 | } |
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80 | |||
81 | /**
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82 | * Returns a List of Lists: all combinations of the elements of the given List.
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83 | * @param maxCombinationSize combinations larger than this value are discarded
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84 | * @param mandatoryItem an item that all returned combinations must contain,
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85 | * or null to leave unspecified
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86 | */
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87 | public static List combinations(List original, int maxCombinationSize, |
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88 | Object mandatoryItem) {
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89 | ArrayList combinations = new ArrayList(); |
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90 | |||
91 | //Combinations are given by the bits of each binary number from 1 to 2^N
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92 | for (int i = 1; i <= ((int) Math.pow(2, original.size()) - 1); i++) { |
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93 | ArrayList combination = new ArrayList(); |
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94 | for (int j = 0; j < original.size(); j++) { |
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95 | if ((i & (int) Math.pow(2, j)) > 0) { |
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96 | combination.add(original.get(j)); |
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97 | } |
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98 | } |
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99 | if (combination.size() > maxCombinationSize) {
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100 | continue;
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101 | } |
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102 | if ((mandatoryItem != null) && |
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103 | !combination.contains(mandatoryItem)) { |
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104 | continue;
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105 | } |
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106 | combinations.add(combination); |
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107 | } |
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108 | |||
109 | return combinations;
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110 | } |
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111 | |||
112 | /**
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113 | * Returns a List of Lists: all combinations of the elements of the given List.
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114 | */
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115 | public static List combinations(List original) { |
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116 | return combinations(original, original.size(), null); |
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117 | } |
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118 | |||
119 | public static void removeKeys(Collection keys, Map map) { |
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120 | for (Iterator i = keys.iterator(); i.hasNext();) { |
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121 | Object key = (Object) i.next(); |
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122 | map.remove(key); |
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123 | } |
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124 | } |
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125 | |||
126 | /**
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127 | * The nth key corresponds to the nth value
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128 | */
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129 | public static List[] keysAndCorrespondingValues(Map map) { |
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130 | ArrayList keys = new ArrayList(map.keySet()); |
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131 | ArrayList values = new ArrayList(); |
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132 | for (Iterator i = keys.iterator(); i.hasNext();) { |
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133 | Object key = i.next();
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134 | values.add(map.get(key)); |
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135 | } |
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136 | |||
137 | return new List[] { keys, values }; |
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138 | } |
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139 | |||
140 | public static Collection concatenate(Collection collections) { |
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141 | ArrayList concatenation = new ArrayList(); |
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142 | for (Iterator i = collections.iterator(); i.hasNext();) { |
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143 | Collection collection = (Collection) i.next(); |
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144 | concatenation.addAll(collection); |
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145 | } |
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146 | |||
147 | return concatenation;
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148 | } |
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149 | |||
150 | public static Object randomElement(List list) { |
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151 | return list.get((int) Math.floor(Math.random() * list.size())); |
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152 | } |
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153 | |||
154 | public static SortedSet reverseSortedSet(int[] ints) { |
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155 | TreeSet sortedSet = new TreeSet(Collections.reverseOrder()); |
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156 | for (int i = 0; i < ints.length; i++) { |
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157 | sortedSet.add(new Integer(ints[i])); |
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158 | } |
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159 | |||
160 | return sortedSet;
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161 | } |
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162 | |||
163 | public static List reverse(List list) { |
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164 | Collections.reverse(list);
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165 | |||
166 | return list;
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167 | } |
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168 | |||
169 | /**
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170 | * Data is evenly discarded or duplicated to attain the new size
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171 | */
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172 | public static Collection stretch(Collection source, Collection destination, |
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173 | int destinationSize) {
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174 | Assert.isTrue(destination.isEmpty()); |
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175 | |||
176 | List originalList = source instanceof List ? (List) source |
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177 | : new ArrayList(source); |
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178 | for (int i = 0; i < destinationSize; i++) { |
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179 | destination.add(originalList.get( |
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180 | (int) Math.round( |
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181 | i * originalList.size() / (double) destinationSize)));
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182 | } |
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183 | |||
184 | return destination;
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185 | } |
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186 | |||
187 | public static Object ifNotIn(Object o, Collection c, Object alternative) { |
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188 | return c.contains(o) ? o : alternative;
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189 | } |
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190 | |||
191 | public static void setIfNull(int i, List list, String value) { |
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192 | if (i >= list.size()) {
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193 | resize(list, i + 1);
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194 | } |
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195 | if (list.get(i) != null) { |
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196 | return;
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197 | } |
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198 | list.set(i, value); |
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199 | } |
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200 | |||
201 | public static void resize(List list, int newSize) { |
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202 | if (newSize < list.size()) {
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203 | list.subList(newSize, list.size()).clear(); |
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204 | } else {
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205 | list.addAll(Collections.nCopies(newSize - list.size(), null)); |
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206 | } |
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207 | } |
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208 | |||
209 | public static boolean containsReference(Object[] objects, Object o) { |
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210 | return indexOf(o, objects) > -1; |
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211 | } |
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212 | |||
213 | public static int indexOf(Object o, Object[] objects) { |
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214 | for (int i = 0; i < objects.length; i++) { |
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215 | if (objects[i] == o) {
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216 | return i;
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217 | } |
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218 | } |
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219 | |||
220 | return -1; |
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221 | } |
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222 | |||
223 | /**
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224 | * Brute force, for when HashSet and TreeSet won't work (e.g. #hashCode
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225 | * implementation isn't appropriate). The original Collection is not modified.
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226 | */
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227 | public static Collection removeDuplicates(Collection original) { |
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228 | ArrayList result = new ArrayList(); |
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229 | for (Iterator i = original.iterator(); i.hasNext();) { |
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230 | Object item = i.next();
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231 | if (!result.contains(item)) {
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232 | result.add(item); |
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233 | } |
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234 | } |
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235 | |||
236 | return result;
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237 | } |
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238 | |||
239 | public static void addIfNotNull(Object item, Collection collection) { |
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240 | if (item != null) { |
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241 | collection.add(item); |
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242 | } |
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243 | } |
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244 | |||
245 | /**
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246 | * Modifies and returns the collection.
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247 | */
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248 | public static Collection filterByClass(Collection collection, Class c) { |
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249 | for (Iterator i = collection.iterator(); i.hasNext();) { |
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250 | Object item = i.next();
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251 | if (!c.isInstance(item)) {
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252 | i.remove(); |
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253 | } |
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254 | } |
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255 | |||
256 | return collection;
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257 | } |
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258 | |||
259 | public static Map createMap(Object[] alternatingKeysAndValues) { |
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260 | return createMap(HashMap.class, alternatingKeysAndValues); |
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261 | } |
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262 | |||
263 | public static Map createMap(Class mapClass, |
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264 | Object[] alternatingKeysAndValues) { |
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265 | Map map = null; |
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266 | try {
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267 | map = (Map) mapClass.newInstance();
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268 | } catch (Exception e) { |
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269 | Assert.shouldNeverReachHere(e.toString()); |
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270 | } |
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271 | for (int i = 0; i < alternatingKeysAndValues.length; i += 2) { |
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272 | map.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + |
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273 | 1]);
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274 | } |
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275 | |||
276 | return map;
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277 | } |
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278 | |||
279 | /**
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280 | * The Smalltalk #collect method.
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281 | */
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282 | public static Collection collect(Collection collection, Block block) { |
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283 | ArrayList result = new ArrayList(); |
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284 | for (Iterator i = collection.iterator(); i.hasNext();) { |
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285 | Object item = i.next();
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286 | result.add(block.yield(item)); |
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287 | } |
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288 | |||
289 | return result;
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290 | } |
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291 | |||
292 | /**
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293 | * The Smalltalk #select method.
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294 | */
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295 | public static Collection select(Collection collection, Block block) { |
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296 | ArrayList result = new ArrayList(); |
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297 | for (Iterator i = collection.iterator(); i.hasNext();) { |
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298 | Object item = i.next();
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299 | if (Boolean.TRUE.equals(block.yield(item))) { |
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300 | result.add(item); |
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301 | } |
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302 | ; |
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303 | } |
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304 | |||
305 | return result;
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306 | } |
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307 | |||
308 | public static Object get(Class c, Map map) { |
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309 | if (map.keySet().contains(c)) {
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310 | return map.get(c);
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311 | } |
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312 | for (Iterator i = map.keySet().iterator(); i.hasNext();) { |
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313 | Class candidateClass = (Class) i.next(); |
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314 | if (candidateClass.isAssignableFrom(c)) {
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315 | return map.get(candidateClass);
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316 | } |
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317 | } |
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318 | |||
319 | return null; |
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320 | } |
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321 | } |