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Comparing jsr166/src/main/java/util/AbstractMap.java (file contents):
Revision 1.8 by jsr166, Wed Apr 27 07:13:50 2005 UTC vs.
Revision 1.26 by jsr166, Sun May 18 23:47:55 2008 UTC

# Line 1 | Line 1
1   /*
2 < * %W% %E%
2 > * Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
3 > * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *
5 < * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
6 < * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5 > * This code is free software; you can redistribute it and/or modify it
6 > * under the terms of the GNU General Public License version 2 only, as
7 > * published by the Free Software Foundation.  Sun designates this
8 > * particular file as subject to the "Classpath" exception as provided
9 > * by Sun in the LICENSE file that accompanied this code.
10 > *
11 > * This code is distributed in the hope that it will be useful, but WITHOUT
12 > * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 > * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 > * version 2 for more details (a copy is included in the LICENSE file that
15 > * accompanied this code).
16 > *
17 > * You should have received a copy of the GNU General Public License version
18 > * 2 along with this work; if not, write to the Free Software Foundation,
19 > * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 > *
21 > * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 > * CA 95054 USA or visit www.sun.com if you need additional information or
23 > * have any questions.
24   */
25  
26   package java.util;
# Line 10 | Line 28 | import java.util.Map.Entry;
28  
29   /**
30   * This class provides a skeletal implementation of the <tt>Map</tt>
31 < * interface, to minimize the effort required to implement this interface. <p>
31 > * interface, to minimize the effort required to implement this interface.
32   *
33 < * To implement an unmodifiable map, the programmer needs only to extend this
33 > * <p>To implement an unmodifiable map, the programmer needs only to extend this
34   * class and provide an implementation for the <tt>entrySet</tt> method, which
35   * returns a set-view of the map's mappings.  Typically, the returned set
36   * will, in turn, be implemented atop <tt>AbstractSet</tt>.  This set should
37   * not support the <tt>add</tt> or <tt>remove</tt> methods, and its iterator
38 < * should not support the <tt>remove</tt> method.<p>
38 > * should not support the <tt>remove</tt> method.
39   *
40 < * To implement a modifiable map, the programmer must additionally override
40 > * <p>To implement a modifiable map, the programmer must additionally override
41   * this class's <tt>put</tt> method (which otherwise throws an
42   * <tt>UnsupportedOperationException</tt>), and the iterator returned by
43   * <tt>entrySet().iterator()</tt> must additionally implement its
44 < * <tt>remove</tt> method.<p>
44 > * <tt>remove</tt> method.
45   *
46 < * The programmer should generally provide a void (no argument) and map
46 > * <p>The programmer should generally provide a void (no argument) and map
47   * constructor, as per the recommendation in the <tt>Map</tt> interface
48 < * specification.<p>
48 > * specification.
49   *
50 < * The documentation for each non-abstract methods in this class describes its
50 > * <p>The documentation for each non-abstract method in this class describes its
51   * implementation in detail.  Each of these methods may be overridden if the
52 < * map being implemented admits a more efficient implementation.<p>
52 > * map being implemented admits a more efficient implementation.
53   *
54 < * This class is a member of the
55 < * <a href="{@docRoot}/../guide/collections/index.html">
54 > * <p>This class is a member of the
55 > * <a href="{@docRoot}/../technotes/guides/collections/index.html">
56   * Java Collections Framework</a>.
57   *
58   * @param <K> the type of keys maintained by this map
# Line 59 | Line 77 | public abstract class AbstractMap<K,V> i
77      // Query Operations
78  
79      /**
80 <     * Returns the number of key-value mappings in this map.  If the map
63 <     * contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
64 <     * <tt>Integer.MAX_VALUE</tt>.<p>
65 <     *
66 <     * This implementation returns <tt>entrySet().size()</tt>.
80 >     * {@inheritDoc}
81       *
82 <     * @return the number of key-value mappings in this map.
82 >     * <p>This implementation returns <tt>entrySet().size()</tt>.
83       */
84      public int size() {
85 <        return entrySet().size();
85 >        return entrySet().size();
86      }
87  
88      /**
89 <     * Returns <tt>true</tt> if this map contains no key-value mappings. <p>
89 >     * {@inheritDoc}
90       *
91 <     * This implementation returns <tt>size() == 0</tt>.
78 <     *
79 <     * @return <tt>true</tt> if this map contains no key-value mappings.
91 >     * <p>This implementation returns <tt>size() == 0</tt>.
92       */
93      public boolean isEmpty() {
94 <        return size() == 0;
94 >        return size() == 0;
95      }
96  
97      /**
98 <     * Returns <tt>true</tt> if this map maps one or more keys to this value.
87 <     * More formally, returns <tt>true</tt> if and only if this map contains
88 <     * at least one mapping to a value <tt>v</tt> such that <tt>(value==null ?
89 <     * v==null : value.equals(v))</tt>.  This operation will probably require
90 <     * time linear in the map size for most implementations of <tt>Map</tt>.<p>
91 <     *
92 <     * This implementation iterates over <tt>entrySet()</tt> searching for an entry
93 <     * with the specified value.  If such an entry is found, <tt>true</tt> is
94 <     * returned.  If the iteration terminates without finding such an entry,
95 <     * <tt>false</tt> is returned.  Note that this implementation requires
96 <     * linear time in the size of the map.
98 >     * {@inheritDoc}
99       *
100 <     * @param value value whose presence in this map is to be tested.
100 >     * <p>This implementation iterates over <tt>entrySet()</tt> searching
101 >     * for an entry with the specified value.  If such an entry is found,
102 >     * <tt>true</tt> is returned.  If the iteration terminates without
103 >     * finding such an entry, <tt>false</tt> is returned.  Note that this
104 >     * implementation requires linear time in the size of the map.
105       *
106 <     * @return <tt>true</tt> if this map maps one or more keys to this value.
106 >     * @throws ClassCastException   {@inheritDoc}
107 >     * @throws NullPointerException {@inheritDoc}
108       */
109      public boolean containsValue(Object value) {
110 <        Iterator<Entry<K,V>> i = entrySet().iterator();
111 <        if (value==null) {
112 <            while (i.hasNext()) {
113 <                Entry<K,V> e = i.next();
114 <                if (e.getValue()==null)
115 <                    return true;
116 <            }
117 <        } else {
118 <            while (i.hasNext()) {
119 <                Entry<K,V> e = i.next();
120 <                if (value.equals(e.getValue()))
121 <                    return true;
122 <            }
123 <        }
124 <        return false;
110 >        Iterator<Entry<K,V>> i = entrySet().iterator();
111 >        if (value==null) {
112 >            while (i.hasNext()) {
113 >                Entry<K,V> e = i.next();
114 >                if (e.getValue()==null)
115 >                    return true;
116 >            }
117 >        } else {
118 >            while (i.hasNext()) {
119 >                Entry<K,V> e = i.next();
120 >                if (value.equals(e.getValue()))
121 >                    return true;
122 >            }
123 >        }
124 >        return false;
125      }
126  
127      /**
128 <     * Returns <tt>true</tt> if this map contains a mapping for the specified
129 <     * key. <p>
130 <     *
131 <     * This implementation iterates over <tt>entrySet()</tt> searching for an
132 <     * entry with the specified key.  If such an entry is found, <tt>true</tt>
133 <     * is returned.  If the iteration terminates without finding such an
134 <     * entry, <tt>false</tt> is returned.  Note that this implementation
135 <     * requires linear time in the size of the map; many implementations will
136 <     * override this method.
137 <     *
138 <     * @param key key whose presence in this map is to be tested.
132 <     * @return <tt>true</tt> if this map contains a mapping for the specified
133 <     *         key.
134 <     * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>
135 <     *         and this map does not permit <tt>null</tt> keys.
128 >     * {@inheritDoc}
129 >     *
130 >     * <p>This implementation iterates over <tt>entrySet()</tt> searching
131 >     * for an entry with the specified key.  If such an entry is found,
132 >     * <tt>true</tt> is returned.  If the iteration terminates without
133 >     * finding such an entry, <tt>false</tt> is returned.  Note that this
134 >     * implementation requires linear time in the size of the map; many
135 >     * implementations will override this method.
136 >     *
137 >     * @throws ClassCastException   {@inheritDoc}
138 >     * @throws NullPointerException {@inheritDoc}
139       */
140      public boolean containsKey(Object key) {
141 <        Iterator<Map.Entry<K,V>> i = entrySet().iterator();
142 <        if (key==null) {
143 <            while (i.hasNext()) {
144 <                Entry<K,V> e = i.next();
145 <                if (e.getKey()==null)
146 <                    return true;
147 <            }
148 <        } else {
149 <            while (i.hasNext()) {
150 <                Entry<K,V> e = i.next();
151 <                if (key.equals(e.getKey()))
152 <                    return true;
153 <            }
154 <        }
155 <        return false;
141 >        Iterator<Map.Entry<K,V>> i = entrySet().iterator();
142 >        if (key==null) {
143 >            while (i.hasNext()) {
144 >                Entry<K,V> e = i.next();
145 >                if (e.getKey()==null)
146 >                    return true;
147 >            }
148 >        } else {
149 >            while (i.hasNext()) {
150 >                Entry<K,V> e = i.next();
151 >                if (key.equals(e.getKey()))
152 >                    return true;
153 >            }
154 >        }
155 >        return false;
156      }
157  
158      /**
159 <     * Returns the value to which this map maps the specified key.  Returns
157 <     * <tt>null</tt> if the map contains no mapping for this key.  A return
158 <     * value of <tt>null</tt> does not <i>necessarily</i> indicate that the
159 <     * map contains no mapping for the key; it's also possible that the map
160 <     * explicitly maps the key to <tt>null</tt>.  The containsKey operation
161 <     * may be used to distinguish these two cases. <p>
162 <     *
163 <     * This implementation iterates over <tt>entrySet()</tt> searching for an
164 <     * entry with the specified key.  If such an entry is found, the entry's
165 <     * value is returned.  If the iteration terminates without finding such an
166 <     * entry, <tt>null</tt> is returned.  Note that this implementation
167 <     * requires linear time in the size of the map; many implementations will
168 <     * override this method.
169 <     *
170 <     * @param key key whose associated value is to be returned.
171 <     * @return the value to which this map maps the specified key.
159 >     * {@inheritDoc}
160       *
161 <     * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>
162 <     *         and this map does not permit <tt>null</tt> keys.
161 >     * <p>This implementation iterates over <tt>entrySet()</tt> searching
162 >     * for an entry with the specified key.  If such an entry is found,
163 >     * the entry's value is returned.  If the iteration terminates without
164 >     * finding such an entry, <tt>null</tt> is returned.  Note that this
165 >     * implementation requires linear time in the size of the map; many
166 >     * implementations will override this method.
167       *
168 <     * @see #containsKey(Object)
168 >     * @throws ClassCastException            {@inheritDoc}
169 >     * @throws NullPointerException          {@inheritDoc}
170       */
171      public V get(Object key) {
172 <        Iterator<Entry<K,V>> i = entrySet().iterator();
173 <        if (key==null) {
174 <            while (i.hasNext()) {
175 <                Entry<K,V> e = i.next();
176 <                if (e.getKey()==null)
177 <                    return e.getValue();
178 <            }
179 <        } else {
180 <            while (i.hasNext()) {
181 <                Entry<K,V> e = i.next();
182 <                if (key.equals(e.getKey()))
183 <                    return e.getValue();
184 <            }
185 <        }
186 <        return null;
172 >        Iterator<Entry<K,V>> i = entrySet().iterator();
173 >        if (key==null) {
174 >            while (i.hasNext()) {
175 >                Entry<K,V> e = i.next();
176 >                if (e.getKey()==null)
177 >                    return e.getValue();
178 >            }
179 >        } else {
180 >            while (i.hasNext()) {
181 >                Entry<K,V> e = i.next();
182 >                if (key.equals(e.getKey()))
183 >                    return e.getValue();
184 >            }
185 >        }
186 >        return null;
187      }
188  
189  
190      // Modification Operations
191  
192      /**
193 <     * Associates the specified value with the specified key in this map
201 <     * (optional operation).  If the map previously contained a mapping for
202 <     * this key, the old value is replaced.<p>
193 >     * {@inheritDoc}
194       *
195 <     * This implementation always throws an
195 >     * <p>This implementation always throws an
196       * <tt>UnsupportedOperationException</tt>.
197       *
198 <     * @param key key with which the specified value is to be associated.
199 <     * @param value value to be associated with the specified key.
200 <     *
201 <     * @return the previous value associated with specified key, or <tt>null</tt>
211 <     *         if there was no mapping for key.  (A <tt>null</tt> return can
212 <     *         also indicate that the map previously associated <tt>null</tt>
213 <     *         with the specified key, if the implementation supports
214 <     *         <tt>null</tt> values.)
215 <     *
216 <     * @throws UnsupportedOperationException if the <tt>put</tt> operation
217 <     *         is not supported by this map.
218 <     * @throws ClassCastException if the class of the specified key or value
219 <     *         prevents it from being stored in this map.
220 <     * @throws IllegalArgumentException if some aspect of this key or value
221 <     *         prevents it from being stored in this map.
222 <     * @throws NullPointerException if this map does not permit <tt>null</tt>
223 <     *         keys or values, and the specified key or value is <tt>null</tt>.
198 >     * @throws UnsupportedOperationException {@inheritDoc}
199 >     * @throws ClassCastException            {@inheritDoc}
200 >     * @throws NullPointerException          {@inheritDoc}
201 >     * @throws IllegalArgumentException      {@inheritDoc}
202       */
203      public V put(K key, V value) {
204 <        throw new UnsupportedOperationException();
204 >        throw new UnsupportedOperationException();
205      }
206  
207      /**
208 <     * Removes the mapping for this key from this map if present (optional
231 <     * operation). <p>
208 >     * {@inheritDoc}
209       *
210 <     * This implementation iterates over <tt>entrySet()</tt> searching for an
210 >     * <p>This implementation iterates over <tt>entrySet()</tt> searching for an
211       * entry with the specified key.  If such an entry is found, its value is
212       * obtained with its <tt>getValue</tt> operation, the entry is removed
213       * from the collection (and the backing map) with the iterator's
214       * <tt>remove</tt> operation, and the saved value is returned.  If the
215       * iteration terminates without finding such an entry, <tt>null</tt> is
216       * returned.  Note that this implementation requires linear time in the
217 <     * size of the map; many implementations will override this method.<p>
217 >     * size of the map; many implementations will override this method.
218 >     *
219 >     * <p>Note that this implementation throws an
220 >     * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt>
221 >     * iterator does not support the <tt>remove</tt> method and this map
222 >     * contains a mapping for the specified key.
223       *
224 <     * Note that this implementation throws an
225 <     * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> iterator
226 <     * does not support the <tt>remove</tt> method and this map contains a
245 <     * mapping for the specified key.
246 <     *
247 <     * @param key key whose mapping is to be removed from the map.
248 <     * @return the previous value associated with specified key, or <tt>null</tt>
249 <     *         if there was no entry for key.  (A <tt>null</tt> return can
250 <     *         also indicate that the map previously associated <tt>null</tt>
251 <     *         with the specified key, if the implementation supports
252 <     *         <tt>null</tt> values.)
253 <     * @throws UnsupportedOperationException if the <tt>remove</tt> operation
254 <     *         is not supported by this map.
224 >     * @throws UnsupportedOperationException {@inheritDoc}
225 >     * @throws ClassCastException            {@inheritDoc}
226 >     * @throws NullPointerException          {@inheritDoc}
227       */
228      public V remove(Object key) {
229 <        Iterator<Entry<K,V>> i = entrySet().iterator();
230 <        Entry<K,V> correctEntry = null;
231 <        if (key==null) {
232 <            while (correctEntry==null && i.hasNext()) {
233 <                Entry<K,V> e = i.next();
234 <                if (e.getKey()==null)
235 <                    correctEntry = e;
236 <            }
237 <        } else {
238 <            while (correctEntry==null && i.hasNext()) {
239 <                Entry<K,V> e = i.next();
240 <                if (key.equals(e.getKey()))
241 <                    correctEntry = e;
242 <            }
243 <        }
244 <
245 <        V oldValue = null;
246 <        if (correctEntry !=null) {
247 <            oldValue = correctEntry.getValue();
248 <            i.remove();
249 <        }
250 <        return oldValue;
229 >        Iterator<Entry<K,V>> i = entrySet().iterator();
230 >        Entry<K,V> correctEntry = null;
231 >        if (key==null) {
232 >            while (correctEntry==null && i.hasNext()) {
233 >                Entry<K,V> e = i.next();
234 >                if (e.getKey()==null)
235 >                    correctEntry = e;
236 >            }
237 >        } else {
238 >            while (correctEntry==null && i.hasNext()) {
239 >                Entry<K,V> e = i.next();
240 >                if (key.equals(e.getKey()))
241 >                    correctEntry = e;
242 >            }
243 >        }
244 >
245 >        V oldValue = null;
246 >        if (correctEntry !=null) {
247 >            oldValue = correctEntry.getValue();
248 >            i.remove();
249 >        }
250 >        return oldValue;
251      }
252  
253  
254      // Bulk Operations
255  
256      /**
257 <     * Copies all of the mappings from the specified map to this map
286 <     * (optional operation).  These mappings will replace any mappings that
287 <     * this map had for any of the keys currently in the specified map.<p>
257 >     * {@inheritDoc}
258       *
259 <     * This implementation iterates over the specified map's
259 >     * <p>This implementation iterates over the specified map's
260       * <tt>entrySet()</tt> collection, and calls this map's <tt>put</tt>
261 <     * operation once for each entry returned by the iteration.<p>
261 >     * operation once for each entry returned by the iteration.
262       *
263 <     * Note that this implementation throws an
263 >     * <p>Note that this implementation throws an
264       * <tt>UnsupportedOperationException</tt> if this map does not support
265       * the <tt>put</tt> operation and the specified map is nonempty.
266       *
267 <     * @param t mappings to be stored in this map.
268 <     *
269 <     * @throws UnsupportedOperationException if the <tt>putAll</tt> operation
270 <     *         is not supported by this map.
301 <     * @throws ClassCastException if the class of a key or value in the
302 <     *         specified map prevents it from being stored in this map.
303 <     * @throws IllegalArgumentException if some aspect of a key or value in
304 <     *         the specified map prevents it from being stored in this map.
305 <     * @throws NullPointerException if the specified map is <tt>null</tt>, or if
306 <     *         this map does not permit <tt>null</tt> keys or values, and the
307 <     *         specified map contains <tt>null</tt> keys or values.
267 >     * @throws UnsupportedOperationException {@inheritDoc}
268 >     * @throws ClassCastException            {@inheritDoc}
269 >     * @throws NullPointerException          {@inheritDoc}
270 >     * @throws IllegalArgumentException      {@inheritDoc}
271       */
272 <    public void putAll(Map<? extends K, ? extends V> t) {
273 <        Iterator<? extends Entry<? extends K, ? extends V>> i = t.entrySet().iterator();
274 <        while (i.hasNext()) {
312 <            Entry<? extends K, ? extends V> e = i.next();
313 <            put(e.getKey(), e.getValue());
314 <        }
272 >    public void putAll(Map<? extends K, ? extends V> m) {
273 >        for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
274 >            put(e.getKey(), e.getValue());
275      }
276  
277      /**
278 <     * Removes all mappings from this map (optional operation). <p>
278 >     * {@inheritDoc}
279       *
280 <     * This implementation calls <tt>entrySet().clear()</tt>.
280 >     * <p>This implementation calls <tt>entrySet().clear()</tt>.
281       *
282 <     * Note that this implementation throws an
282 >     * <p>Note that this implementation throws an
283       * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt>
284       * does not support the <tt>clear</tt> operation.
285       *
286 <     * @throws UnsupportedOperationException if the <tt>clear</tt> operation
327 <     *         is not supported by this map.
286 >     * @throws UnsupportedOperationException {@inheritDoc}
287       */
288      public void clear() {
289 <        entrySet().clear();
289 >        entrySet().clear();
290      }
291  
292  
# Line 342 | Line 301 | public abstract class AbstractMap<K,V> i
301      transient volatile Collection<V> values = null;
302  
303      /**
304 <     * Returns a {@link Set} view of the keys contained in this map.
346 <     * The set is backed by the map, so changes to the map are
347 <     * reflected in the set, and vice-versa.  If the map is modified
348 <     * while an iteration over the set is in progress (except through
349 <     * the iterator's own <tt>remove</tt> operation), the results of
350 <     * the iteration are undefined.  The set supports element removal,
351 <     * which removes the corresponding mapping from the map, via the
352 <     * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
353 <     * <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt>
354 <     * operations.  It does not support the add or <tt>addAll</tt>
355 <     * operations.
304 >     * {@inheritDoc}
305       *
306       * <p>This implementation returns a set that subclasses {@link AbstractSet}.
307       * The subclass's iterator method returns a "wrapper object" over this
# Line 367 | Line 316 | public abstract class AbstractMap<K,V> i
316       * method will not all return the same set.
317       */
318      public Set<K> keySet() {
319 <        if (keySet == null) {
320 <            keySet = new AbstractSet<K>() {
321 <                public Iterator<K> iterator() {
322 <                    return new Iterator<K>() {
323 <                        private Iterator<Entry<K,V>> i = entrySet().iterator();
324 <
325 <                        public boolean hasNext() {
326 <                            return i.hasNext();
327 <                        }
328 <
329 <                        public K next() {
330 <                            return i.next().getKey();
331 <                        }
332 <
333 <                        public void remove() {
334 <                            i.remove();
335 <                        }
319 >        if (keySet == null) {
320 >            keySet = new AbstractSet<K>() {
321 >                public Iterator<K> iterator() {
322 >                    return new Iterator<K>() {
323 >                        private Iterator<Entry<K,V>> i = entrySet().iterator();
324 >
325 >                        public boolean hasNext() {
326 >                            return i.hasNext();
327 >                        }
328 >
329 >                        public K next() {
330 >                            return i.next().getKey();
331 >                        }
332 >
333 >                        public void remove() {
334 >                            i.remove();
335 >                        }
336                      };
337 <                }
337 >                }
338 >
339 >                public int size() {
340 >                    return AbstractMap.this.size();
341 >                }
342 >
343 >                public boolean isEmpty() {
344 >                    return AbstractMap.this.isEmpty();
345 >                }
346 >
347 >                public void clear() {
348 >                    AbstractMap.this.clear();
349 >                }
350  
351 <                public int size() {
352 <                    return AbstractMap.this.size();
353 <                }
354 <
355 <                public boolean contains(Object k) {
356 <                    return AbstractMap.this.containsKey(k);
396 <                }
397 <            };
398 <        }
399 <        return keySet;
351 >                public boolean contains(Object k) {
352 >                    return AbstractMap.this.containsKey(k);
353 >                }
354 >            };
355 >        }
356 >        return keySet;
357      }
358  
359      /**
360 <     * Returns a {@link Collection} view of the values contained in this map.
404 <     * The collection is backed by the map, so changes to the map are
405 <     * reflected in the collection, and vice-versa.  If the map is
406 <     * modified while an iteration over the collection is in progress
407 <     * (except through the iterator's own <tt>remove</tt> operation),
408 <     * the results of the iteration are undefined.  The collection
409 <     * supports element removal, which removes the corresponding
410 <     * mapping from the map, via the <tt>Iterator.remove</tt>,
411 <     * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
412 <     * <tt>retainAll</tt> and <tt>clear</tt> operations.  It does not
413 <     * support the add or <tt>addAll</tt> operations.
360 >     * {@inheritDoc}
361       *
362       * <p>This implementation returns a collection that subclasses {@link
363       * AbstractCollection}.  The subclass's iterator method returns a
# Line 423 | Line 370 | public abstract class AbstractMap<K,V> i
370       * returned in response to all subsequent calls.  No synchronization is
371       * performed, so there is a slight chance that multiple calls to this
372       * method will not all return the same collection.
426     *
427     * @return a collection view of the values contained in this map.
373       */
374      public Collection<V> values() {
375 <        if (values == null) {
376 <            values = new AbstractCollection<V>() {
377 <                public Iterator<V> iterator() {
378 <                    return new Iterator<V>() {
379 <                        private Iterator<Entry<K,V>> i = entrySet().iterator();
380 <
381 <                        public boolean hasNext() {
382 <                            return i.hasNext();
383 <                        }
384 <
385 <                        public V next() {
386 <                            return i.next().getValue();
387 <                        }
388 <
389 <                        public void remove() {
390 <                            i.remove();
391 <                        }
375 >        if (values == null) {
376 >            values = new AbstractCollection<V>() {
377 >                public Iterator<V> iterator() {
378 >                    return new Iterator<V>() {
379 >                        private Iterator<Entry<K,V>> i = entrySet().iterator();
380 >
381 >                        public boolean hasNext() {
382 >                            return i.hasNext();
383 >                        }
384 >
385 >                        public V next() {
386 >                            return i.next().getValue();
387 >                        }
388 >
389 >                        public void remove() {
390 >                            i.remove();
391 >                        }
392                      };
393                  }
394  
395 <                public int size() {
396 <                    return AbstractMap.this.size();
397 <                }
398 <
399 <                public boolean contains(Object v) {
400 <                    return AbstractMap.this.containsValue(v);
401 <                }
402 <            };
403 <        }
404 <        return values;
395 >                public int size() {
396 >                    return AbstractMap.this.size();
397 >                }
398 >
399 >                public boolean isEmpty() {
400 >                    return AbstractMap.this.isEmpty();
401 >                }
402 >
403 >                public void clear() {
404 >                    AbstractMap.this.clear();
405 >                }
406 >
407 >                public boolean contains(Object v) {
408 >                    return AbstractMap.this.containsValue(v);
409 >                }
410 >            };
411 >        }
412 >        return values;
413      }
414  
415      public abstract Set<Entry<K,V>> entrySet();
# Line 467 | Line 420 | public abstract class AbstractMap<K,V> i
420      /**
421       * Compares the specified object with this map for equality.  Returns
422       * <tt>true</tt> if the given object is also a map and the two maps
423 <     * represent the same mappings.  More formally, two maps <tt>t1</tt> and
424 <     * <tt>t2</tt> represent the same mappings if
425 <     * <tt>t1.keySet().equals(t2.keySet())</tt> and for every key <tt>k</tt>
473 <     * in <tt>t1.keySet()</tt>, <tt> (t1.get(k)==null ? t2.get(k)==null :
474 <     * t1.get(k).equals(t2.get(k))) </tt>.  This ensures that the
423 >     * represent the same mappings.  More formally, two maps <tt>m1</tt> and
424 >     * <tt>m2</tt> represent the same mappings if
425 >     * <tt>m1.entrySet().equals(m2.entrySet())</tt>.  This ensures that the
426       * <tt>equals</tt> method works properly across different implementations
427 <     * of the map interface.<p>
427 >     * of the <tt>Map</tt> interface.
428       *
429 <     * This implementation first checks if the specified object is this map;
429 >     * <p>This implementation first checks if the specified object is this map;
430       * if so it returns <tt>true</tt>.  Then, it checks if the specified
431       * object is a map whose size is identical to the size of this map; if
432       * not, it returns <tt>false</tt>.  If so, it iterates over this map's
# Line 484 | Line 435 | public abstract class AbstractMap<K,V> i
435       * fails to contain such a mapping, <tt>false</tt> is returned.  If the
436       * iteration completes, <tt>true</tt> is returned.
437       *
438 <     * @param o object to be compared for equality with this map.
439 <     * @return <tt>true</tt> if the specified object is equal to this map.
438 >     * @param o object to be compared for equality with this map
439 >     * @return <tt>true</tt> if the specified object is equal to this map
440       */
441      public boolean equals(Object o) {
442 <        if (o == this)
443 <            return true;
442 >        if (o == this)
443 >            return true;
444  
445 <        if (!(o instanceof Map))
446 <            return false;
447 <        Map<K,V> t = (Map<K,V>) o;
448 <        if (t.size() != size())
449 <            return false;
445 >        if (!(o instanceof Map))
446 >            return false;
447 >        Map<K,V> m = (Map<K,V>) o;
448 >        if (m.size() != size())
449 >            return false;
450  
451          try {
452              Iterator<Entry<K,V>> i = entrySet().iterator();
453              while (i.hasNext()) {
454                  Entry<K,V> e = i.next();
455 <                K key = e.getKey();
455 >                K key = e.getKey();
456                  V value = e.getValue();
457                  if (value == null) {
458 <                    if (!(t.get(key)==null && t.containsKey(key)))
458 >                    if (!(m.get(key)==null && m.containsKey(key)))
459                          return false;
460                  } else {
461 <                    if (!value.equals(t.get(key)))
461 >                    if (!value.equals(m.get(key)))
462                          return false;
463                  }
464              }
# Line 517 | Line 468 | public abstract class AbstractMap<K,V> i
468              return false;
469          }
470  
471 <        return true;
471 >        return true;
472      }
473  
474      /**
475       * Returns the hash code value for this map.  The hash code of a map is
476       * defined to be the sum of the hash codes of each entry in the map's
477 <     * <tt>entrySet()</tt> view.  This ensures that <tt>t1.equals(t2)</tt>
478 <     * implies that <tt>t1.hashCode()==t2.hashCode()</tt> for any two maps
479 <     * <tt>t1</tt> and <tt>t2</tt>, as required by the general contract of
480 <     * Object.hashCode.<p>
481 <     *
482 <     * This implementation iterates over <tt>entrySet()</tt>, calling
483 <     * <tt>hashCode</tt> on each element (entry) in the Collection, and adding
484 <     * up the results.
477 >     * <tt>entrySet()</tt> view.  This ensures that <tt>m1.equals(m2)</tt>
478 >     * implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps
479 >     * <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of
480 >     * {@link Object#hashCode}.
481 >     *
482 >     * <p>This implementation iterates over <tt>entrySet()</tt>, calling
483 >     * {@link Map.Entry#hashCode hashCode()} on each element (entry) in the
484 >     * set, and adding up the results.
485       *
486 <     * @return the hash code value for this map.
486 >     * @return the hash code value for this map
487       * @see Map.Entry#hashCode()
537     * @see Object#hashCode()
488       * @see Object#equals(Object)
489       * @see Set#equals(Object)
490       */
491      public int hashCode() {
492 <        int h = 0;
493 <        Iterator<Entry<K,V>> i = entrySet().iterator();
494 <        while (i.hasNext())
495 <            h += i.next().hashCode();
496 <        return h;
492 >        int h = 0;
493 >        Iterator<Entry<K,V>> i = entrySet().iterator();
494 >        while (i.hasNext())
495 >            h += i.next().hashCode();
496 >        return h;
497      }
498  
499      /**
# Line 554 | Line 504 | public abstract class AbstractMap<K,V> i
504       * <tt>", "</tt> (comma and space).  Each key-value mapping is rendered as
505       * the key followed by an equals sign (<tt>"="</tt>) followed by the
506       * associated value.  Keys and values are converted to strings as by
507 <     * <tt>String.valueOf(Object)</tt>.<p>
558 <     *
559 <     * This implementation creates an empty string buffer, appends a left
560 <     * brace, and iterates over the map's <tt>entrySet</tt> view, appending
561 <     * the string representation of each <tt>map.entry</tt> in turn.  After
562 <     * appending each entry except the last, the string <tt>", "</tt> is
563 <     * appended.  Finally a right brace is appended.  A string is obtained
564 <     * from the stringbuffer, and returned.
507 >     * {@link String#valueOf(Object)}.
508       *
509 <     * @return a String representation of this map.
509 >     * @return a string representation of this map
510       */
511      public String toString() {
512 <        StringBuffer buf = new StringBuffer();
513 <        buf.append("{");
514 <
515 <        Iterator<Entry<K,V>> i = entrySet().iterator();
516 <        boolean hasNext = i.hasNext();
517 <        while (hasNext) {
518 <            Entry<K,V> e = i.next();
519 <            K key = e.getKey();
512 >        Iterator<Entry<K,V>> i = entrySet().iterator();
513 >        if (! i.hasNext())
514 >            return "{}";
515 >
516 >        StringBuilder sb = new StringBuilder();
517 >        sb.append('{');
518 >        for (;;) {
519 >            Entry<K,V> e = i.next();
520 >            K key = e.getKey();
521              V value = e.getValue();
522 <            if (key == this)
523 <                buf.append("(this Map)");
524 <            else
525 <                buf.append(key);
526 <            buf.append("=");
527 <            if (value == this)
584 <                buf.append("(this Map)");
585 <            else
586 <                buf.append(value);
587 <            hasNext = i.hasNext();
588 <            if (hasNext)
589 <                buf.append(", ");
522 >            sb.append(key   == this ? "(this Map)" : key);
523 >            sb.append('=');
524 >            sb.append(value == this ? "(this Map)" : value);
525 >            if (! i.hasNext())
526 >                return sb.append('}').toString();
527 >            sb.append(", ");
528          }
591
592        buf.append("}");
593        return buf.toString();
529      }
530  
531      /**
532       * Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys
533       * and values themselves are not cloned.
534       *
535 <     * @return a shallow copy of this map.
535 >     * @return a shallow copy of this map
536       */
537      protected Object clone() throws CloneNotSupportedException {
538          AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone();
# Line 611 | Line 546 | public abstract class AbstractMap<K,V> i
546       * Test for equality, checking for nulls.
547       */
548      private static boolean eq(Object o1, Object o2) {
549 <        return (o1 == null ? o2 == null : o1.equals(o2));
549 >        return o1 == null ? o2 == null : o1.equals(o2);
550      }
551  
552      // Implementation Note: SimpleEntry and SimpleImmutableEntry
# Line 628 | Line 563 | public abstract class AbstractMap<K,V> i
563       * facilitates the process of building custom map
564       * implementations. For example, it may be convenient to return
565       * arrays of <tt>SimpleEntry</tt> instances in method
566 <     * <tt>Map.entrySet().toArray</tt>
566 >     * <tt>Map.entrySet().toArray</tt>.
567 >     *
568 >     * @since 1.6
569       */
570 <    public static class SimpleEntry<K,V> implements Entry<K,V> {
571 <        private final K key;
572 <        private V value;
570 >    public static class SimpleEntry<K,V>
571 >        implements Entry<K,V>, java.io.Serializable
572 >    {
573 >        private static final long serialVersionUID = -8499721149061103585L;
574 >
575 >        private final K key;
576 >        private V value;
577  
578          /**
579           * Creates an entry representing a mapping from the specified
# Line 641 | Line 582 | public abstract class AbstractMap<K,V> i
582           * @param key the key represented by this entry
583           * @param value the value represented by this entry
584           */
585 <        public SimpleEntry(K key, V value) {
586 <            this.key   = key;
585 >        public SimpleEntry(K key, V value) {
586 >            this.key   = key;
587              this.value = value;
588 <        }
588 >        }
589  
590          /**
591           * Creates an entry representing the same mapping as the
592           * specified entry.
593           *
594 <         * @param entry the entry to copy.
594 >         * @param entry the entry to copy
595           */
596 <        public SimpleEntry(Entry<? extends K, ? extends V> entry) {
597 <            this.key   = entry.getKey();
596 >        public SimpleEntry(Entry<? extends K, ? extends V> entry) {
597 >            this.key   = entry.getKey();
598              this.value = entry.getValue();
599 <        }
599 >        }
600 >
601 >        /**
602 >         * Returns the key corresponding to this entry.
603 >         *
604 >         * @return the key corresponding to this entry
605 >         */
606 >        public K getKey() {
607 >            return key;
608 >        }
609 >
610 >        /**
611 >         * Returns the value corresponding to this entry.
612 >         *
613 >         * @return the value corresponding to this entry
614 >         */
615 >        public V getValue() {
616 >            return value;
617 >        }
618  
619 <        /**
620 <         * Returns the key corresponding to this entry.
621 <         *
622 <         * @return the key corresponding to this entry.
623 <         */
624 <        public K getKey() {
625 <            return key;
626 <        }
627 <
628 <        /**
629 <         * Returns the value corresponding to this entry.
630 <         *
631 <         * @return the value corresponding to this entry.
632 <         */
633 <        public V getValue() {
634 <            return value;
635 <        }
636 <
637 <        /**
638 <         * Replaces the value corresponding to this entry with the specified
639 <         * value.
640 <         *
641 <         * @param value new value to be stored in this entry.
642 <         * @return the old value corresponding to the entry.
643 <         */
644 <        public V setValue(V value) {
645 <            V oldValue = this.value;
646 <            this.value = value;
647 <            return oldValue;
648 <        }
649 <
650 <        public boolean equals(Object o) {
651 <            if (!(o instanceof Map.Entry))
652 <                return false;
653 <            Map.Entry e = (Map.Entry)o;
654 <            return eq(key, e.getKey()) && eq(value, e.getValue());
655 <        }
656 <
657 <        public int hashCode() {
658 <            return ((key   == null)   ? 0 :   key.hashCode()) ^
659 <                   ((value == null)   ? 0 : value.hashCode());
660 <        }
619 >        /**
620 >         * Replaces the value corresponding to this entry with the specified
621 >         * value.
622 >         *
623 >         * @param value new value to be stored in this entry
624 >         * @return the old value corresponding to the entry
625 >         */
626 >        public V setValue(V value) {
627 >            V oldValue = this.value;
628 >            this.value = value;
629 >            return oldValue;
630 >        }
631 >
632 >        /**
633 >         * Compares the specified object with this entry for equality.
634 >         * Returns {@code true} if the given object is also a map entry and
635 >         * the two entries represent the same mapping.  More formally, two
636 >         * entries {@code e1} and {@code e2} represent the same mapping
637 >         * if<pre>
638 >         *   (e1.getKey()==null ?
639 >         *    e2.getKey()==null :
640 >         *    e1.getKey().equals(e2.getKey()))
641 >         *   &amp;&amp;
642 >         *   (e1.getValue()==null ?
643 >         *    e2.getValue()==null :
644 >         *    e1.getValue().equals(e2.getValue()))</pre>
645 >         * This ensures that the {@code equals} method works properly across
646 >         * different implementations of the {@code Map.Entry} interface.
647 >         *
648 >         * @param o object to be compared for equality with this map entry
649 >         * @return {@code true} if the specified object is equal to this map
650 >         *         entry
651 >         * @see    #hashCode
652 >         */
653 >        public boolean equals(Object o) {
654 >            if (!(o instanceof Map.Entry))
655 >                return false;
656 >            Map.Entry e = (Map.Entry)o;
657 >            return eq(key, e.getKey()) && eq(value, e.getValue());
658 >        }
659 >
660 >        /**
661 >         * Returns the hash code value for this map entry.  The hash code
662 >         * of a map entry {@code e} is defined to be: <pre>
663 >         *   (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
664 >         *   (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
665 >         * This ensures that {@code e1.equals(e2)} implies that
666 >         * {@code e1.hashCode()==e2.hashCode()} for any two Entries
667 >         * {@code e1} and {@code e2}, as required by the general
668 >         * contract of {@link Object#hashCode}.
669 >         *
670 >         * @return the hash code value for this map entry
671 >         * @see    #equals
672 >         */
673 >        public int hashCode() {
674 >            return (key   == null ? 0 :   key.hashCode()) ^
675 >                   (value == null ? 0 : value.hashCode());
676 >        }
677  
678          /**
679           * Returns a String representation of this map entry.  This
# Line 706 | Line 681 | public abstract class AbstractMap<K,V> i
681           * entry's key followed by the equals character ("<tt>=</tt>")
682           * followed by the string representation of this entry's value.
683           *
684 <         * @return a String representation of this map entry.
684 >         * @return a String representation of this map entry
685           */
686 <        public String toString() {
687 <            return key + "=" + value;
688 <        }
686 >        public String toString() {
687 >            return key + "=" + value;
688 >        }
689  
690      }
691  
692      /**
693 <     * An Entry maintaining an immutable key and value, This class
693 >     * An Entry maintaining an immutable key and value.  This class
694       * does not support method <tt>setValue</tt>.  This class may be
695       * convenient in methods that return thread-safe snapshots of
696       * key-value mappings.
697 +     *
698 +     * @since 1.6
699       */
700 <    public static class SimpleImmutableEntry<K,V> implements Entry<K,V> {
701 <        private final K key;
702 <        private final V value;
700 >    public static class SimpleImmutableEntry<K,V>
701 >        implements Entry<K,V>, java.io.Serializable
702 >    {
703 >        private static final long serialVersionUID = 7138329143949025153L;
704 >
705 >        private final K key;
706 >        private final V value;
707  
708          /**
709           * Creates an entry representing a mapping from the specified
# Line 731 | Line 712 | public abstract class AbstractMap<K,V> i
712           * @param key the key represented by this entry
713           * @param value the value represented by this entry
714           */
715 <        public SimpleImmutableEntry(K key, V value) {
716 <            this.key   = key;
715 >        public SimpleImmutableEntry(K key, V value) {
716 >            this.key   = key;
717              this.value = value;
718 <        }
718 >        }
719  
720          /**
721           * Creates an entry representing the same mapping as the
722           * specified entry.
723           *
724 <         * @param entry the entry to copy.
724 >         * @param entry the entry to copy
725           */
726 <        public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) {
727 <            this.key   = entry.getKey();
726 >        public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) {
727 >            this.key   = entry.getKey();
728              this.value = entry.getValue();
729 <        }
729 >        }
730 >
731 >        /**
732 >         * Returns the key corresponding to this entry.
733 >         *
734 >         * @return the key corresponding to this entry
735 >         */
736 >        public K getKey() {
737 >            return key;
738 >        }
739 >
740 >        /**
741 >         * Returns the value corresponding to this entry.
742 >         *
743 >         * @return the value corresponding to this entry
744 >         */
745 >        public V getValue() {
746 >            return value;
747 >        }
748  
749 <        /**
750 <         * Returns the key corresponding to this entry.
751 <         *
753 <         * @return the key corresponding to this entry.
754 <         */
755 <        public K getKey() {
756 <            return key;
757 <        }
758 <
759 <        /**
760 <         * Returns the value corresponding to this entry.
761 <         *
762 <         * @return the value corresponding to this entry.
763 <         */
764 <        public V getValue() {
765 <            return value;
766 <        }
767 <
768 <        /**
769 <         * Replaces the value corresponding to this entry with the specified
770 <         * value (optional operation).  This implementation simply throws
749 >        /**
750 >         * Replaces the value corresponding to this entry with the specified
751 >         * value (optional operation).  This implementation simply throws
752           * <tt>UnsupportedOperationException</tt>, as this class implements
753           * an <i>immutable</i> map entry.
754 <         *
755 <         * @param value new value to be stored in this entry.
756 <         * @return (Does not return)
757 <         * @throws UnsupportedOperationException always
754 >         *
755 >         * @param value new value to be stored in this entry
756 >         * @return (Does not return)
757 >         * @throws UnsupportedOperationException always
758           */
759 <        public V setValue(V value) {
759 >        public V setValue(V value) {
760              throw new UnsupportedOperationException();
761          }
762  
763 <        public boolean equals(Object o) {
764 <            if (!(o instanceof Map.Entry))
765 <                return false;
766 <            Map.Entry e = (Map.Entry)o;
767 <            return eq(key, e.getKey()) && eq(value, e.getValue());
768 <        }
769 <
770 <        public int hashCode() {
771 <            return ((key   == null)   ? 0 :   key.hashCode()) ^
772 <                   ((value == null)   ? 0 : value.hashCode());
773 <        }
763 >        /**
764 >         * Compares the specified object with this entry for equality.
765 >         * Returns {@code true} if the given object is also a map entry and
766 >         * the two entries represent the same mapping.  More formally, two
767 >         * entries {@code e1} and {@code e2} represent the same mapping
768 >         * if<pre>
769 >         *   (e1.getKey()==null ?
770 >         *    e2.getKey()==null :
771 >         *    e1.getKey().equals(e2.getKey()))
772 >         *   &amp;&amp;
773 >         *   (e1.getValue()==null ?
774 >         *    e2.getValue()==null :
775 >         *    e1.getValue().equals(e2.getValue()))</pre>
776 >         * This ensures that the {@code equals} method works properly across
777 >         * different implementations of the {@code Map.Entry} interface.
778 >         *
779 >         * @param o object to be compared for equality with this map entry
780 >         * @return {@code true} if the specified object is equal to this map
781 >         *         entry
782 >         * @see    #hashCode
783 >         */
784 >        public boolean equals(Object o) {
785 >            if (!(o instanceof Map.Entry))
786 >                return false;
787 >            Map.Entry e = (Map.Entry)o;
788 >            return eq(key, e.getKey()) && eq(value, e.getValue());
789 >        }
790 >
791 >        /**
792 >         * Returns the hash code value for this map entry.  The hash code
793 >         * of a map entry {@code e} is defined to be: <pre>
794 >         *   (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
795 >         *   (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
796 >         * This ensures that {@code e1.equals(e2)} implies that
797 >         * {@code e1.hashCode()==e2.hashCode()} for any two Entries
798 >         * {@code e1} and {@code e2}, as required by the general
799 >         * contract of {@link Object#hashCode}.
800 >         *
801 >         * @return the hash code value for this map entry
802 >         * @see    #equals
803 >         */
804 >        public int hashCode() {
805 >            return (key   == null ? 0 :   key.hashCode()) ^
806 >                   (value == null ? 0 : value.hashCode());
807 >        }
808  
809          /**
810           * Returns a String representation of this map entry.  This
# Line 797 | Line 812 | public abstract class AbstractMap<K,V> i
812           * entry's key followed by the equals character ("<tt>=</tt>")
813           * followed by the string representation of this entry's value.
814           *
815 <         * @return a String representation of this map entry.
815 >         * @return a String representation of this map entry
816           */
817 <        public String toString() {
818 <            return key + "=" + value;
819 <        }
817 >        public String toString() {
818 >            return key + "=" + value;
819 >        }
820  
821      }
822  

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