1 /* |
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2 * Copyright (c) 1998, 2000, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 package com.sun.tools.jdi; |
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26 |
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27 import java.io.*; |
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28 import java.util.*; |
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29 |
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30 /** |
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31 * Hash table based implementation of the Map interface. This implementation |
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32 * provides all of the optional Map operations, and permits null values and |
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33 * the null key. (HashMap is roughly equivalent to Hashtable, except that it |
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34 * is unsynchronized and permits nulls.) In addition, elements in the map are |
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35 * ordered and doubly linked together. |
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36 * <p> |
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37 * This implementation provides constant-time performance for the basic |
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38 * operations (get and put), assuming the the hash function disperses the |
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39 * elements properly among the buckets. Iteration over Collection views |
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40 * requires time proportional to its size (the number of key-value mappings) |
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41 * and returns elements in the order they are linked. In a HashMap the |
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42 * iteration would require time proportional to the capacity of the map |
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43 * plus the map size. |
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44 * <p> |
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45 * An instance of LinkedHashMap has two parameters that affect its efficiency: |
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46 * its <i>capacity</i> and its <i>load factor</i>. The load factor should be |
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47 * between 0.0 and 1.0. When the number of mappings in the LinkedHashMap exceeds |
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48 * the product of the load factor and the current capacity, the capacity is |
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49 * increased by calling the rehash method which requires time proportional |
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50 * to the number of key-value mappings in the map. Larger load factors |
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51 * use memory more efficiently, at the expense of larger expected time per |
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52 * lookup. |
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53 * <p> |
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54 * If many mappings are to be stored in a LinkedHashMap, creating it with a |
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55 * sufficiently large capacity will allow the mappings to be stored more |
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56 * efficiently than letting it perform automatic rehashing as needed to grow |
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57 * the table. |
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58 * <p> |
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59 * <strong>Note that this implementation is not synchronized.</strong> If |
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60 * multiple threads access a LinkedHashMap concurrently, and at least one of the |
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61 * threads modifies the LinkedHashMap structurally, it <em>must</em> be |
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62 * synchronized externally. (A structural modification is any operation that |
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63 * adds or deletes one or more mappings; merely changing the value associated |
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64 * with a key that is already contained in the Table is not a structural |
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65 * modification.) This is typically accomplished by synchronizing on some |
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66 * object that naturally encapsulates the LinkedHashMap. If no such object |
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67 * exists, the LinkedHashMap should be "wrapped" using the |
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68 * Collections.synchronizedSet method. This is best done at creation time, to |
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69 * prevent accidental unsynchronized access to the LinkedHashMap: |
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70 * <pre> |
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71 * Map m = Collections.synchronizedMap(new LinkedHashMap(...)); |
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72 * </pre> |
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73 * <p> |
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74 * The Iterators returned by the iterator methods of the Collections returned |
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75 * by all of LinkedHashMap's "collection view methods" are <em>fail-fast</em>: |
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76 * if the LinkedHashMap is structurally modified at any time after the Iterator |
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77 * is created, in any way except through the Iterator's own remove or add |
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78 * methods, the Iterator will throw a ConcurrentModificationException. Thus, |
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79 * in the face of concurrent modification, the Iterator fails quickly and |
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80 * cleanly, rather than risking arbitrary, non-deterministic behavior at an |
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81 * undetermined time in the future. |
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82 * |
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83 * @author Josh Bloch |
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84 * @author Arthur van Hoff |
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85 * @author Zhenghua Li |
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86 * @see Object#hashCode() |
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87 * @see java.util.Collection |
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88 * @see java.util.Map |
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89 * @see java.util.TreeMap |
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90 * @see java.util.Hashtable |
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91 * @see java.util.HashMap |
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92 */ |
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93 |
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94 import java.io.Serializable; |
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95 |
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96 public class LinkedHashMap extends AbstractMap implements Map, Serializable { |
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97 /** |
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98 * The hash table data. |
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99 */ |
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100 private transient Entry table[]; |
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101 |
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102 /** |
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103 * The head of the double linked list. |
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104 */ |
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105 private transient Entry header; |
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106 |
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107 /** |
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108 * The total number of mappings in the hash table. |
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109 */ |
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110 private transient int count; |
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111 |
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112 /** |
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113 * Rehashes the table when count exceeds this threshold. |
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114 */ |
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115 private int threshold; |
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116 |
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117 /** |
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118 * The load factor for the LinkedHashMap. |
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119 */ |
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120 private float loadFactor; |
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121 |
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122 /** |
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123 * The number of times this LinkedHashMap has been structurally modified |
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124 * Structural modifications are those that change the number of mappings in |
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125 * the LinkedHashMap or otherwise modify its internal structure (e.g., |
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126 * rehash). This field is used to make iterators on Collection-views of |
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127 * the LinkedHashMap fail-fast. (See ConcurrentModificationException). |
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128 */ |
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129 private transient int modCount = 0; |
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130 |
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131 /** |
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132 * Constructs a new, empty LinkedHashMap with the specified initial |
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133 * capacity and the specified load factor. |
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134 * |
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135 * @param initialCapacity the initial capacity of the LinkedHashMap. |
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136 * @param loadFactor a number between 0.0 and 1.0. |
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137 * @exception IllegalArgumentException if the initial capacity is less |
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138 * than or equal to zero, or if the load factor is less than |
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139 * or equal to zero. |
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140 */ |
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141 public LinkedHashMap(int initialCapacity, float loadFactor) { |
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142 if (initialCapacity < 0) |
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143 throw new IllegalArgumentException("Illegal Initial Capacity: "+ |
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144 initialCapacity); |
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145 if ((loadFactor > 1) || (loadFactor <= 0)) |
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146 throw new IllegalArgumentException("Illegal Load factor: "+ |
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147 loadFactor); |
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148 if (initialCapacity==0) |
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149 initialCapacity = 1; |
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150 this.loadFactor = loadFactor; |
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151 table = new Entry[initialCapacity]; |
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152 threshold = (int)(initialCapacity * loadFactor); |
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153 header = new Entry(-1, null, null, null); |
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154 header.before = header.after = header; |
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155 } |
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156 |
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157 /** |
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158 * Constructs a new, empty LinkedHashMap with the specified initial capacity |
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159 * and default load factor. |
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160 * |
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161 * @param initialCapacity the initial capacity of the LinkedHashMap. |
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162 */ |
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163 public LinkedHashMap(int initialCapacity) { |
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164 this(initialCapacity, 0.75f); |
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165 } |
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166 |
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167 /** |
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168 * Constructs a new, empty LinkedHashMap with a default capacity and load |
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169 * factor. |
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170 */ |
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171 public LinkedHashMap() { |
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172 this(101, 0.75f); |
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173 } |
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174 |
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175 /** |
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176 * Constructs a new LinkedHashMap with the same mappings as the given |
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177 * Map. The LinkedHashMap is created with a capacity of thrice the number |
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178 * of mappings in the given Map or 11 (whichever is greater), and a |
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179 * default load factor. |
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180 */ |
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181 public LinkedHashMap(Map t) { |
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182 this(Math.max(3*t.size(), 11), 0.75f); |
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183 putAll(t); |
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184 } |
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185 |
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186 /** |
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187 * Returns the number of key-value mappings in this Map. |
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188 */ |
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189 public int size() { |
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190 return count; |
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191 } |
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192 |
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193 /** |
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194 * Returns true if this Map contains no key-value mappings. |
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195 */ |
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196 public boolean isEmpty() { |
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197 return count == 0; |
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198 } |
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199 |
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200 /** |
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201 * Returns true if this LinkedHashMap maps one or more keys to the specified |
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202 * value. |
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203 * |
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204 * @param value value whose presence in this Map is to be tested. |
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205 */ |
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206 public boolean containsValue(Object value) { |
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207 if (value==null) { |
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208 for (Entry e = header.after; e != header; e = e.after) |
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209 if (e.value==null) |
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210 return true; |
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211 } else { |
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212 for (Entry e = header.after; e != header; e = e.after) |
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213 if (value.equals(e.value)) |
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214 return true; |
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215 } |
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216 return false; |
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217 } |
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218 |
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219 /** |
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220 * Returns true if this LinkedHashMap contains a mapping for the specified |
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221 * key. |
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222 * |
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223 * @param key key whose presence in this Map is to be tested. |
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224 */ |
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225 public boolean containsKey(Object key) { |
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226 Entry tab[] = table; |
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227 if (key != null) { |
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228 int hash = key.hashCode(); |
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229 int index = (hash & 0x7FFFFFFF) % tab.length; |
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230 for (Entry e = tab[index]; e != null; e = e.next) |
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231 if (e.hash==hash && e.key.equals(key)) |
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232 return true; |
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233 } else { |
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234 for (Entry e = tab[0]; e != null; e = e.next) |
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235 if (e.key==null) |
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236 return true; |
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237 } |
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238 |
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239 return false; |
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240 } |
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241 |
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242 /** |
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243 * Returns the value to which this LinkedHashMap maps the specified key. |
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244 * Returns null if the LinkedHashMap contains no mapping for this key. |
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245 * A return value of null does not <em>necessarily</em> indicate that the |
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246 * LinkedHashMap contains no mapping for the key; it's also possible that |
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247 * the LinkedHashMap explicitly maps the key to null. The containsKey |
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248 * operation may be used to distinguish these two cases. |
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249 * |
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250 * @param key key whose associated value is to be returned. |
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251 */ |
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252 public Object get(Object key) { |
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253 Entry e = getEntry(key); |
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254 return e==null ? null : e.value; |
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255 } |
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256 |
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257 /** |
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258 * Returns the entry associated with the specified key in the LinkedHashMap. |
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259 * Returns null if the LinkedHashMap contains no mapping for this key. |
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260 */ |
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261 private Entry getEntry(Object key) { |
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262 Entry tab[] = table; |
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263 |
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264 if (key != null) { |
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265 int hash = key.hashCode(); |
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266 int index = (hash & 0x7FFFFFFF) % tab.length; |
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267 for (Entry e = tab[index]; e != null; e = e.next) |
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268 if ((e.hash == hash) && e.key.equals(key)) |
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269 return e; |
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270 } else { |
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271 for (Entry e = tab[0]; e != null; e = e.next) |
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272 if (e.key==null) |
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273 return e; |
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274 } |
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275 |
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276 return null; |
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277 } |
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278 |
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279 /** |
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280 * Rehashes the contents of the LinkedHashMap into a LinkedHashMap with a |
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281 * larger capacity. This method is called automatically when the |
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282 * number of keys in the LinkedHashMap exceeds this LinkedHashMap's capacity |
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283 * and load factor. |
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284 */ |
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285 private void rehash() { |
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286 int oldCapacity = table.length; |
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287 Entry oldMap[] = table; |
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288 |
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289 int newCapacity = oldCapacity * 2 + 1; |
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290 Entry newMap[] = new Entry[newCapacity]; |
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291 |
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292 modCount++; |
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293 threshold = (int)(newCapacity * loadFactor); |
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294 table = newMap; |
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295 |
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296 for (Entry e = header.after; e != header; e = e.after) { |
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297 int index = (e.hash & 0x7FFFFFFF) % newCapacity; |
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298 e.next = newMap[index]; |
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299 newMap[index] = e; |
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300 } |
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301 } |
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302 |
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303 /** |
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304 * Remove an entry from the linked list. |
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305 */ |
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306 private void listRemove(Entry entry) { |
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307 if (entry == null) { |
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308 return; |
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309 } |
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310 entry.before.after = entry.after; |
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311 entry.after.before = entry.before; |
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312 } |
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313 |
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314 /** |
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315 * Add the specified entry before the specified existing entry to |
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316 * the linked list. |
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317 */ |
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318 private void listAddBefore(Entry entry, Entry existEntry) { |
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319 entry.after = existEntry; |
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320 entry.before = existEntry.before; |
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321 entry.before.after = entry; |
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322 entry.after.before = entry; |
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323 } |
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324 |
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325 /** |
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326 * Returns the position of the mapping for the specified key |
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327 * in the ordered map. |
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328 * |
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329 * @param key the specified key. |
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330 * @return index of the key mapping. |
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331 */ |
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332 public int indexOf(Object key) { |
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333 int i = 0; |
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334 if (key == null) { |
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335 for (Entry e = header.after; e != header; e = e.after, i++) |
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336 if (e.key == null) |
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337 return i; |
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338 } else { |
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339 for (Entry e = header.after; e != header; e = e.after, i++) |
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340 if(key.equals(e.key)) |
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341 return i; |
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342 } |
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343 return -1; |
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344 } |
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345 |
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346 /** |
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347 * Associates the specified value with the specified key in this |
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348 * LinkedHashMap. If the LinkedHashMap previously contained a mapping for |
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349 * this key, the old value is replaced and the position of this mapping |
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350 * entry in the double linked list remains the same. Otherwise, a new |
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351 * mapping entry is created and inserted into the list before the specified |
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352 * existing mapping entry. The method returns the previous value associated |
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353 * with the specified key, or null if there was no mapping for key. A null |
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354 * return can also indicate that the LinkedHashMap previously associated |
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355 * null with the specified key. |
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356 */ |
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357 private Object putAhead(Object key, Object value, Entry existEntry) { |
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358 // Makes sure the key is not already in the LinkedHashMap. |
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359 Entry tab[] = table; |
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360 int hash = 0; |
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361 int index = 0; |
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362 |
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363 if (key != null) { |
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364 hash = key.hashCode(); |
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365 index = (hash & 0x7FFFFFFF) % tab.length; |
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366 for (Entry e = tab[index] ; e != null ; e = e.next) { |
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367 if ((e.hash == hash) && e.key.equals(key)) { |
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368 Object old = e.value; |
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369 e.value = value; |
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370 return old; |
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371 } |
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372 } |
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373 } else { |
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374 for (Entry e = tab[0] ; e != null ; e = e.next) { |
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375 if (e.key == null) { |
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376 Object old = e.value; |
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377 e.value = value; |
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378 return old; |
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379 } |
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380 } |
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381 } |
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382 |
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383 modCount++; |
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384 if (count >= threshold) { |
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385 // Rehash the table if the threshold is exceeded |
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386 rehash(); |
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387 tab = table; |
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388 index = (hash & 0x7FFFFFFF) % tab.length; |
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389 } |
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390 |
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391 // Creates the new entry. |
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392 Entry e = new Entry(hash, key, value, tab[index]); |
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393 tab[index] = e; |
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394 listAddBefore(e, existEntry); |
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395 count++; |
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396 return null; |
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397 } |
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398 |
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399 /** |
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400 * Associates the specified value with the specified key in this |
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401 * LinkedHashMap and position the mapping at the specified index. |
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402 * If the LinkedHashMap previously contained a mapping for this key, |
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403 * the old value is replaced and the position of this mapping entry |
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404 * in the double linked list remains the same. Otherwise, a new mapping |
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405 * entry is created and inserted into the list at the specified |
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406 * position. |
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407 * |
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408 * @param index the position to put the key-value mapping. |
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409 * @param key key with which the specified value is to be associated. |
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410 * @param value value to be associated with the specified key. |
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411 * @return previous value associated with specified key, or null if there |
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412 * was no mapping for key. A null return can also indicate that |
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413 * the LinkedHashMap previously associated null with the specified |
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414 * key. |
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415 */ |
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416 public Object put(int index, Object key, Object value) { |
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417 if (index < 0 || index > count) |
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418 throw new IndexOutOfBoundsException(); |
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419 Entry e = header.after; |
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420 if (index == count) |
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421 return putAhead(key, value, header); //fast approach for append |
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422 else { |
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423 for (int i = 0; i < index; i++) |
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424 e = e.after; |
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425 return putAhead(key, value, e); |
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426 } |
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427 } |
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428 |
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429 |
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430 /** |
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431 * Associates the specified value with the specified key in this |
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432 * LinkedHashMap. If the LinkedHashMap previously contained a mapping for |
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433 * this key, the old value is replaced. The mapping entry is also appended |
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434 * to the end of the ordered linked list. |
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435 * |
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436 * @param key key with which the specified value is to be associated. |
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437 * @param value value to be associated with the specified key. |
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438 * @return previous value associated with specified key, or null if there |
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439 * was no mapping for key. A null return can also indicate that |
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440 * the LinkedHashMap previously associated null with the specified |
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441 * key. |
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442 */ |
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443 public Object put(Object key, Object value) { |
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444 return putAhead(key, value, header); |
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445 } |
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446 |
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447 /** |
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448 * Removes the mapping for this key from this LinkedHashMap if present. |
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449 * The mapping would also be removed from the double linked list. |
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450 * |
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451 * @param key key whose mapping is to be removed from the Map. |
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452 * @return previous value associated with specified key, or null if there |
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453 * was no mapping for key. A null return can also indicate that |
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454 * the LinkedHashMap previously associated null with the specified |
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455 * key. |
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456 */ |
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457 public Object remove(Object key) { |
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458 Entry tab[] = table; |
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459 |
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460 if (key != null) { |
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461 int hash = key.hashCode(); |
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462 int index = (hash & 0x7FFFFFFF) % tab.length; |
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463 |
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464 for (Entry e = tab[index], prev = null; e != null; |
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465 prev = e, e = e.next) { |
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466 if ((e.hash == hash) && e.key.equals(key)) { |
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467 modCount++; |
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468 if (prev != null) |
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469 prev.next = e.next; |
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470 else |
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471 tab[index] = e.next; |
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472 |
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473 count--; |
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474 Object oldValue = e.value; |
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475 e.value = null; |
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476 |
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477 listRemove(e); |
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478 return oldValue; |
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479 } |
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480 } |
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481 } else { |
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482 for (Entry e = tab[0], prev = null; e != null; |
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483 prev = e, e = e.next) { |
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484 if (e.key == null) { |
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485 modCount++; |
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486 if (prev != null) |
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487 prev.next = e.next; |
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488 else |
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489 tab[0] = e.next; |
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490 |
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491 count--; |
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492 Object oldValue = e.value; |
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493 e.value = null; |
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494 |
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495 listRemove(e); |
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496 return oldValue; |
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497 } |
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498 } |
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499 } |
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500 |
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501 return null; |
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502 } |
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503 |
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504 /** |
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505 * Copies all of the mappings from the specified Map to this LinkedHashMap |
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506 * These mappings will replace any mappings that this LinkedHashMap had for |
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507 * any of the keys currently in the specified Map. |
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508 * |
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509 * @param t Mappings to be stored in this Map. |
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510 */ |
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511 public void putAll(Map t) { |
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512 Iterator i = t.entrySet().iterator(); |
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513 while (i.hasNext()) { |
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514 Map.Entry e = (Map.Entry) i.next(); |
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515 put(e.getKey(), e.getValue()); |
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516 } |
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517 } |
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518 |
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519 /** |
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520 * Removes all mappings from this LinkedHashMap. |
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521 */ |
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522 public void clear() { |
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523 Entry tab[] = table; |
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524 modCount++; |
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525 for (int index = tab.length; --index >= 0; ) |
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526 tab[index] = null; |
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527 count = 0; |
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528 header.before = header.after = header; |
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529 } |
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530 |
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531 /** |
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532 * Returns a shallow copy of this LinkedHashMap. The keys and values |
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533 * themselves are not cloned. |
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534 */ |
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535 public Object clone() { |
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536 return new LinkedHashMap(this); |
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537 } |
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538 |
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539 // Views |
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540 |
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541 private transient Set keySet = null; |
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542 private transient Set entries = null; |
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543 private transient Collection values = null; |
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544 |
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545 /** |
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546 * Returns a Set view of the keys contained in this LinkedHashMap. The Set |
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547 * is backed by the LinkedHashMap, so changes to the LinkedHashMap are |
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548 * reflected in the Set, and vice-versa. The Set supports element removal, |
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549 * which removes the corresponding mapping from the LinkedHashMap, via the |
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550 * Iterator.remove, Set.remove, removeAll retainAll, and clear operations. |
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551 * It does not support the add or addAll operations. |
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552 */ |
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553 public Set keySet() { |
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554 if (keySet == null) { |
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555 keySet = new AbstractSet() { |
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556 public Iterator iterator() { |
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557 return new HashIterator(KEYS); |
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558 } |
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559 public int size() { |
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560 return count; |
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561 } |
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562 public boolean contains(Object o) { |
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563 return containsKey(o); |
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564 } |
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565 public boolean remove(Object o) { |
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566 return LinkedHashMap.this.remove(o) != null; |
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567 } |
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568 public void clear() { |
|
569 LinkedHashMap.this.clear(); |
|
570 } |
|
571 }; |
|
572 } |
|
573 return keySet; |
|
574 } |
|
575 |
|
576 /** |
|
577 * Returns a Collection view of the values contained in this LinkedHashMap. |
|
578 * The Collection is backed by the LinkedHashMap, so changes to the |
|
579 * LinkedHashMap are reflected in the Collection, and vice-versa. The |
|
580 * Collection supports element removal, which removes the corresponding |
|
581 * mapping from the LinkedHashMap, via the Iterator.remove, |
|
582 * Collection.remove, removeAll, retainAll and clear operations. It does |
|
583 * not support the add or addAll operations. |
|
584 */ |
|
585 public Collection values() { |
|
586 if (values==null) { |
|
587 values = new AbstractCollection() { |
|
588 public Iterator iterator() { |
|
589 return new HashIterator(VALUES); |
|
590 } |
|
591 public int size() { |
|
592 return count; |
|
593 } |
|
594 public boolean contains(Object o) { |
|
595 return containsValue(o); |
|
596 } |
|
597 public void clear() { |
|
598 LinkedHashMap.this.clear(); |
|
599 } |
|
600 }; |
|
601 } |
|
602 return values; |
|
603 } |
|
604 |
|
605 /** |
|
606 * Returns a Collection view of the mappings contained in this |
|
607 * LinkedHashMap. Each element in the returned collection is a Map.Entry. |
|
608 * The Collection is backed by the LinkedHashMap, so changes to the |
|
609 * LinkedHashMap are reflected in the Collection, and vice-versa. The |
|
610 * Collection supports element removal, which removes the corresponding |
|
611 * mapping from the LinkedHashMap, via the Iterator.remove, |
|
612 * Collection.remove, removeAll, retainAll and clear operations. It does |
|
613 * not support the add or addAll operations. |
|
614 * |
|
615 * @see java.util.Map.Entry |
|
616 */ |
|
617 public Set entrySet() { |
|
618 if (entries==null) { |
|
619 entries = new AbstractSet() { |
|
620 public Iterator iterator() { |
|
621 return new HashIterator(ENTRIES); |
|
622 } |
|
623 |
|
624 public boolean contains(Object o) { |
|
625 if (!(o instanceof Map.Entry)) |
|
626 return false; |
|
627 Map.Entry entry = (Map.Entry)o; |
|
628 Object key = entry.getKey(); |
|
629 Entry tab[] = table; |
|
630 int hash = (key==null ? 0 : key.hashCode()); |
|
631 int index = (hash & 0x7FFFFFFF) % tab.length; |
|
632 |
|
633 for (Entry e = tab[index]; e != null; e = e.next) |
|
634 if (e.hash==hash && e.equals(entry)) |
|
635 return true; |
|
636 return false; |
|
637 } |
|
638 |
|
639 public boolean remove(Object o) { |
|
640 if (!(o instanceof Map.Entry)) |
|
641 return false; |
|
642 Map.Entry entry = (Map.Entry)o; |
|
643 Object key = entry.getKey(); |
|
644 Entry tab[] = table; |
|
645 int hash = (key==null ? 0 : key.hashCode()); |
|
646 int index = (hash & 0x7FFFFFFF) % tab.length; |
|
647 |
|
648 for (Entry e = tab[index], prev = null; e != null; |
|
649 prev = e, e = e.next) { |
|
650 if (e.hash==hash && e.equals(entry)) { |
|
651 modCount++; |
|
652 if (prev != null) |
|
653 prev.next = e.next; |
|
654 else |
|
655 tab[index] = e.next; |
|
656 |
|
657 count--; |
|
658 e.value = null; |
|
659 listRemove(e); |
|
660 return true; |
|
661 } |
|
662 } |
|
663 return false; |
|
664 } |
|
665 |
|
666 public int size() { |
|
667 return count; |
|
668 } |
|
669 |
|
670 public void clear() { |
|
671 LinkedHashMap.this.clear(); |
|
672 } |
|
673 }; |
|
674 } |
|
675 |
|
676 return entries; |
|
677 } |
|
678 |
|
679 /** |
|
680 * Compares the specified Object with this Map for equality. |
|
681 * Returns true if the given object is also a LinkedHashMap and the two |
|
682 * Maps represent the same mappings in the same order. More formally, |
|
683 * two Maps <code>t1</code> and <code>t2</code> represent the same mappings |
|
684 * if <code>t1.keySet().equals(t2.keySet())</code> and for every |
|
685 * key <code>k</code> in <code>t1.keySet()</code>, <code> |
|
686 * (t1.get(k)==null ? t2.get(k)==null : t1.get(k).equals(t2.get(k))) |
|
687 * </code>. |
|
688 * <p> |
|
689 * This implementation first checks if the specified Object is this Map; |
|
690 * if so it returns true. Then, it checks if the specified Object is |
|
691 * a Map whose size is identical to the size of this Set; if not, it |
|
692 * it returns false. If so, it iterates over this Map and the specified |
|
693 * Map's entrySet() Collection, and checks that the specified Map contains |
|
694 * each mapping that this Map contains at the same position. If the |
|
695 * specified Map fails to contain such a mapping in the right order, false |
|
696 * is returned. If the iteration completes, true is returned. |
|
697 * |
|
698 * @param o Object to be compared for equality with this Map. |
|
699 * @return true if the specified Object is equal to this Map. |
|
700 * |
|
701 */ |
|
702 public boolean equals(Object o) { |
|
703 if (o == this) |
|
704 return true; |
|
705 |
|
706 if (!(o instanceof LinkedHashMap)) |
|
707 return false; |
|
708 LinkedHashMap t = (LinkedHashMap) o; |
|
709 if (t.size() != size()) |
|
710 return false; |
|
711 |
|
712 Iterator i1 = entrySet().iterator(); |
|
713 Iterator i2 = t.entrySet().iterator(); |
|
714 |
|
715 while (i1.hasNext()) { |
|
716 Entry e1 = (Entry) i1.next(); |
|
717 Entry e2 = (Entry) i2.next(); |
|
718 |
|
719 Object key1 = e1.getKey(); |
|
720 Object value1 = e1.getValue(); |
|
721 Object key2 = e2.getKey(); |
|
722 Object value2 = e2.getValue(); |
|
723 |
|
724 if ((key1 == null ? key2 == null : key1.equals(key2)) && |
|
725 (value1 == null ? value2 == null : value1.equals(value2))) { |
|
726 continue; |
|
727 } else { |
|
728 return false; |
|
729 } |
|
730 } |
|
731 return true; |
|
732 } |
|
733 |
|
734 /** |
|
735 * LinkedHashMap collision list entry. |
|
736 */ |
|
737 private static class Entry implements Map.Entry { |
|
738 int hash; |
|
739 Object key; |
|
740 Object value; |
|
741 Entry next; |
|
742 |
|
743 // These fields comprise the doubly linked list that is used for |
|
744 // iteration. |
|
745 Entry before, after; |
|
746 |
|
747 Entry(int hash, Object key, Object value, Entry next) { |
|
748 this.hash = hash; |
|
749 this.key = key; |
|
750 this.value = value; |
|
751 this.next = next; |
|
752 } |
|
753 |
|
754 // Map.Entry Ops |
|
755 |
|
756 public Object getKey() { |
|
757 return key; |
|
758 } |
|
759 |
|
760 public Object getValue() { |
|
761 return value; |
|
762 } |
|
763 |
|
764 public Object setValue(Object value) { |
|
765 Object oldValue = this.value; |
|
766 this.value = value; |
|
767 return oldValue; |
|
768 } |
|
769 |
|
770 public boolean equals(Object o) { |
|
771 if (!(o instanceof Map.Entry)) |
|
772 return false; |
|
773 Map.Entry e = (Map.Entry)o; |
|
774 |
|
775 return (key==null ? e.getKey()==null : key.equals(e.getKey())) && |
|
776 (value==null ? e.getValue()==null : value.equals(e.getValue())); |
|
777 } |
|
778 |
|
779 public int hashCode() { |
|
780 return hash ^ (value==null ? 0 : value.hashCode()); |
|
781 } |
|
782 |
|
783 public String toString() { |
|
784 return key+"="+value; |
|
785 } |
|
786 } |
|
787 |
|
788 // Types of Iterators |
|
789 private static final int KEYS = 0; |
|
790 private static final int VALUES = 1; |
|
791 private static final int ENTRIES = 2; |
|
792 |
|
793 private class HashIterator implements Iterator { |
|
794 private Entry[] table = LinkedHashMap.this.table; |
|
795 private Entry entry = null; |
|
796 private Entry lastReturned = null; |
|
797 private int type; |
|
798 |
|
799 /** |
|
800 * The modCount value that the iterator believes that the backing |
|
801 * List should have. If this expectation is violated, the iterator |
|
802 * has detected concurrent modification. |
|
803 */ |
|
804 private int expectedModCount = modCount; |
|
805 |
|
806 HashIterator(int type) { |
|
807 this.type = type; |
|
808 this.entry = LinkedHashMap.this.header.after; |
|
809 } |
|
810 |
|
811 public boolean hasNext() { |
|
812 return entry != header; |
|
813 } |
|
814 |
|
815 public Object next() { |
|
816 if (modCount != expectedModCount) |
|
817 throw new ConcurrentModificationException(); |
|
818 if (entry == LinkedHashMap.this.header) |
|
819 throw new NoSuchElementException(); |
|
820 |
|
821 Entry e = lastReturned = entry; |
|
822 entry = e.after; |
|
823 return type == KEYS ? e.key : (type == VALUES ? e.value : e); |
|
824 } |
|
825 |
|
826 public void remove() { |
|
827 if (lastReturned == null) |
|
828 throw new IllegalStateException(); |
|
829 if (modCount != expectedModCount) |
|
830 throw new ConcurrentModificationException(); |
|
831 |
|
832 Entry[] tab = LinkedHashMap.this.table; |
|
833 int index = (lastReturned.hash & 0x7FFFFFFF) % tab.length; |
|
834 |
|
835 for (Entry e = tab[index], prev = null; e != null; |
|
836 prev = e, e = e.next) { |
|
837 if (e == lastReturned) { |
|
838 modCount++; |
|
839 expectedModCount++; |
|
840 if (prev == null) |
|
841 tab[index] = e.next; |
|
842 else |
|
843 prev.next = e.next; |
|
844 count--; |
|
845 listRemove(e); |
|
846 lastReturned = null; |
|
847 return; |
|
848 } |
|
849 } |
|
850 throw new ConcurrentModificationException(); |
|
851 } |
|
852 } |
|
853 |
|
854 /** |
|
855 * Save the state of the LinkedHashMap to a stream (i.e., serialize it). |
|
856 * The objects will be written out in the order they are linked |
|
857 * in the list. |
|
858 */ |
|
859 private void writeObject(java.io.ObjectOutputStream s) |
|
860 throws IOException |
|
861 { |
|
862 // Write out the threshold, loadfactor, and any hidden stuff |
|
863 s.defaultWriteObject(); |
|
864 |
|
865 // Write out number of buckets |
|
866 s.writeInt(table.length); |
|
867 |
|
868 // Write out size (number of Mappings) |
|
869 s.writeInt(count); |
|
870 |
|
871 // Write out keys and values (alternating) |
|
872 for (Entry e = header.after; e != header; e = e.after) { |
|
873 s.writeObject(e.key); |
|
874 s.writeObject(e.value); |
|
875 } |
|
876 } |
|
877 |
|
878 /** |
|
879 * Reconstitute the LinkedHashMap from a stream (i.e., deserialize it). |
|
880 */ |
|
881 private void readObject(java.io.ObjectInputStream s) |
|
882 throws IOException, ClassNotFoundException |
|
883 { |
|
884 // Read in the threshold, loadfactor, and any hidden stuff |
|
885 s.defaultReadObject(); |
|
886 |
|
887 // Read in number of buckets and allocate the bucket array; |
|
888 int numBuckets = s.readInt(); |
|
889 table = new Entry[numBuckets]; |
|
890 header = new Entry(-1, null, null, null); |
|
891 header.before = header; |
|
892 header.after = header; |
|
893 |
|
894 // Read in size (number of Mappings) |
|
895 int size = s.readInt(); |
|
896 |
|
897 // Read the keys and values, and put the mappings in the LinkedHashMap |
|
898 for (int i=0; i<size; i++) { |
|
899 Object key = s.readObject(); |
|
900 Object value = s.readObject(); |
|
901 put(key, value); |
|
902 } |
|
903 } |
|
904 } |
|