1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util;
27
28 import java.util.Map.Entry;
29 import sun.misc.SharedSecrets;
30
31 /**
32 * A specialized {@link Map} implementation for use with enum type keys. All
33 * of the keys in an enum map must come from a single enum type that is
34 * specified, explicitly or implicitly, when the map is created. Enum maps
35 * are represented internally as arrays. This representation is extremely
36 * compact and efficient.
37 *
38 * <p>Enum maps are maintained in the <i>natural order</i> of their keys
39 * (the order in which the enum constants are declared). This is reflected
40 * in the iterators returned by the collections views ({@link #keySet()},
41 * {@link #entrySet()}, and {@link #values()}).
42 *
43 * <p>Iterators returned by the collection views are <i>weakly consistent</i>:
44 * they will never throw {@link ConcurrentModificationException} and they may
45 * or may not show the effects of any modifications to the map that occur while
46 * the iteration is in progress.
47 *
48 * <p>Null keys are not permitted. Attempts to insert a null key will
49 * throw {@link NullPointerException}. Attempts to test for the
50 * presence of a null key or to remove one will, however, function properly.
51 * Null values are permitted.
52
53 * <P>Like most collection implementations <tt>EnumMap</tt> is not
54 * synchronized. If multiple threads access an enum map concurrently, and at
55 * least one of the threads modifies the map, it should be synchronized
56 * externally. This is typically accomplished by synchronizing on some
57 * object that naturally encapsulates the enum map. If no such object exists,
58 * the map should be "wrapped" using the {@link Collections#synchronizedMap}
59 * method. This is best done at creation time, to prevent accidental
60 * unsynchronized access:
61 *
62 * <pre>
63 * Map<EnumKey, V> m
64 * = Collections.synchronizedMap(new EnumMap<EnumKey, V>(...));
65 * </pre>
66 *
67 * <p>Implementation note: All basic operations execute in constant time.
68 * They are likely (though not guaranteed) to be faster than their
69 * {@link HashMap} counterparts.
70 *
71 * <p>This class is a member of the
72 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
73 * Java Collections Framework</a>.
74 *
75 * @author Josh Bloch
76 * @see EnumSet
77 * @since 1.5
78 */
79 public class EnumMap<K extends Enum<K>, V> extends AbstractMap<K, V>
80 implements java.io.Serializable, Cloneable
81 {
82 /**
83 * The <tt>Class</tt> object for the enum type of all the keys of this map.
84 *
85 * @serial
86 */
87 private final Class<K> keyType;
88
89 /**
90 * All of the values comprising K. (Cached for performance.)
91 */
92 private transient K[] keyUniverse;
93
94 /**
95 * Array representation of this map. The ith element is the value
96 * to which universe[i] is currently mapped, or null if it isn't
97 * mapped to anything, or NULL if it's mapped to null.
98 */
99 private transient Object[] vals;
100
101 /**
102 * The number of mappings in this map.
103 */
104 private transient int size = 0;
105
106 /**
107 * Distinguished non-null value for representing null values.
108 */
109 private static final Object NULL = new Object() {
110 public int hashCode() {
111 return 0;
112 }
113
114 public String toString() {
115 return "java.util.EnumMap.NULL";
116 }
117 };
118
119 private Object maskNull(Object value) {
120 return (value == null ? NULL : value);
121 }
122
123 @SuppressWarnings("unchecked")
124 private V unmaskNull(Object value) {
125 return (V)(value == NULL ? null : value);
126 }
127
128 private static final Enum<?>[] ZERO_LENGTH_ENUM_ARRAY = new Enum<?>[0];
129
130 /**
131 * Creates an empty enum map with the specified key type.
132 *
133 * @param keyType the class object of the key type for this enum map
134 * @throws NullPointerException if <tt>keyType</tt> is null
135 */
136 public EnumMap(Class<K> keyType) {
137 this.keyType = keyType;
138 keyUniverse = getKeyUniverse(keyType);
139 vals = new Object[keyUniverse.length];
140 }
141
142 /**
143 * Creates an enum map with the same key type as the specified enum
144 * map, initially containing the same mappings (if any).
145 *
146 * @param m the enum map from which to initialize this enum map
147 * @throws NullPointerException if <tt>m</tt> is null
148 */
149 public EnumMap(EnumMap<K, ? extends V> m) {
150 keyType = m.keyType;
151 keyUniverse = m.keyUniverse;
152 vals = m.vals.clone();
153 size = m.size;
154 }
155
156 /**
157 * Creates an enum map initialized from the specified map. If the
158 * specified map is an <tt>EnumMap</tt> instance, this constructor behaves
159 * identically to {@link #EnumMap(EnumMap)}. Otherwise, the specified map
160 * must contain at least one mapping (in order to determine the new
161 * enum map's key type).
162 *
163 * @param m the map from which to initialize this enum map
164 * @throws IllegalArgumentException if <tt>m</tt> is not an
165 * <tt>EnumMap</tt> instance and contains no mappings
166 * @throws NullPointerException if <tt>m</tt> is null
167 */
168 public EnumMap(Map<K, ? extends V> m) {
169 if (m instanceof EnumMap) {
170 EnumMap<K, ? extends V> em = (EnumMap<K, ? extends V>) m;
171 keyType = em.keyType;
172 keyUniverse = em.keyUniverse;
173 vals = em.vals.clone();
174 size = em.size;
175 } else {
176 if (m.isEmpty())
177 throw new IllegalArgumentException("Specified map is empty");
178 keyType = m.keySet().iterator().next().getDeclaringClass();
179 keyUniverse = getKeyUniverse(keyType);
180 vals = new Object[keyUniverse.length];
181 putAll(m);
182 }
183 }
184
185 // Query Operations
186
187 /**
188 * Returns the number of key-value mappings in this map.
189 *
190 * @return the number of key-value mappings in this map
191 */
192 public int size() {
193 return size;
194 }
195
196 /**
197 * Returns <tt>true</tt> if this map maps one or more keys to the
198 * specified value.
199 *
200 * @param value the value whose presence in this map is to be tested
201 * @return <tt>true</tt> if this map maps one or more keys to this value
202 */
203 public boolean containsValue(Object value) {
204 value = maskNull(value);
205
206 for (Object val : vals)
207 if (value.equals(val))
208 return true;
209
210 return false;
211 }
212
213 /**
214 * Returns <tt>true</tt> if this map contains a mapping for the specified
215 * key.
216 *
217 * @param key the key whose presence in this map is to be tested
218 * @return <tt>true</tt> if this map contains a mapping for the specified
219 * key
220 */
221 public boolean containsKey(Object key) {
222 return isValidKey(key) && vals[((Enum<?>)key).ordinal()] != null;
223 }
224
225 private boolean containsMapping(Object key, Object value) {
226 return isValidKey(key) &&
227 maskNull(value).equals(vals[((Enum<?>)key).ordinal()]);
228 }
229
230 /**
231 * Returns the value to which the specified key is mapped,
232 * or {@code null} if this map contains no mapping for the key.
233 *
234 * <p>More formally, if this map contains a mapping from a key
235 * {@code k} to a value {@code v} such that {@code (key == k)},
236 * then this method returns {@code v}; otherwise it returns
237 * {@code null}. (There can be at most one such mapping.)
238 *
239 * <p>A return value of {@code null} does not <i>necessarily</i>
240 * indicate that the map contains no mapping for the key; it's also
241 * possible that the map explicitly maps the key to {@code null}.
242 * The {@link #containsKey containsKey} operation may be used to
243 * distinguish these two cases.
244 */
245 public V get(Object key) {
246 return (isValidKey(key) ?
247 unmaskNull(vals[((Enum<?>)key).ordinal()]) : null);
248 }
249
250 // Modification Operations
251
252 /**
253 * Associates the specified value with the specified key in this map.
254 * If the map previously contained a mapping for this key, the old
255 * value is replaced.
256 *
257 * @param key the key with which the specified value is to be associated
258 * @param value the value to be associated with the specified key
259 *
260 * @return the previous value associated with specified key, or
261 * <tt>null</tt> if there was no mapping for key. (A <tt>null</tt>
262 * return can also indicate that the map previously associated
263 * <tt>null</tt> with the specified key.)
264 * @throws NullPointerException if the specified key is null
265 */
266 public V put(K key, V value) {
267 typeCheck(key);
268
269 int index = key.ordinal();
270 Object oldValue = vals[index];
271 vals[index] = maskNull(value);
272 if (oldValue == null)
273 size++;
274 return unmaskNull(oldValue);
275 }
276
277 /**
278 * Removes the mapping for this key from this map if present.
279 *
280 * @param key the key whose mapping is to be removed from the map
281 * @return the previous value associated with specified key, or
282 * <tt>null</tt> if there was no entry for key. (A <tt>null</tt>
283 * return can also indicate that the map previously associated
284 * <tt>null</tt> with the specified key.)
285 */
286 public V remove(Object key) {
287 if (!isValidKey(key))
288 return null;
289 int index = ((Enum<?>)key).ordinal();
290 Object oldValue = vals[index];
291 vals[index] = null;
292 if (oldValue != null)
293 size--;
294 return unmaskNull(oldValue);
295 }
296
297 private boolean removeMapping(Object key, Object value) {
298 if (!isValidKey(key))
299 return false;
300 int index = ((Enum<?>)key).ordinal();
301 if (maskNull(value).equals(vals[index])) {
302 vals[index] = null;
303 size--;
304 return true;
305 }
306 return false;
307 }
308
309 /**
310 * Returns true if key is of the proper type to be a key in this
311 * enum map.
312 */
313 private boolean isValidKey(Object key) {
314 if (key == null)
315 return false;
316
317 // Cheaper than instanceof Enum followed by getDeclaringClass
318 Class<?> keyClass = key.getClass();
319 return keyClass == keyType || keyClass.getSuperclass() == keyType;
320 }
321
322 // Bulk Operations
323
324 /**
325 * Copies all of the mappings from the specified map to this map.
326 * These mappings will replace any mappings that this map had for
327 * any of the keys currently in the specified map.
328 *
329 * @param m the mappings to be stored in this map
330 * @throws NullPointerException the specified map is null, or if
331 * one or more keys in the specified map are null
332 */
333 public void putAll(Map<? extends K, ? extends V> m) {
334 if (m instanceof EnumMap) {
335 EnumMap<?, ?> em = (EnumMap<?, ?>)m;
336 if (em.keyType != keyType) {
337 if (em.isEmpty())
338 return;
339 throw new ClassCastException(em.keyType + " != " + keyType);
340 }
341
342 for (int i = 0; i < keyUniverse.length; i++) {
343 Object emValue = em.vals[i];
344 if (emValue != null) {
345 if (vals[i] == null)
346 size++;
347 vals[i] = emValue;
348 }
349 }
350 } else {
351 super.putAll(m);
352 }
353 }
354
355 /**
356 * Removes all mappings from this map.
357 */
358 public void clear() {
359 Arrays.fill(vals, null);
360 size = 0;
361 }
362
363 // Views
364
365 /**
366 * This field is initialized to contain an instance of the entry set
367 * view the first time this view is requested. The view is stateless,
368 * so there's no reason to create more than one.
369 */
370 private transient Set<Map.Entry<K,V>> entrySet;
371
372 /**
373 * Returns a {@link Set} view of the keys contained in this map.
374 * The returned set obeys the general contract outlined in
375 * {@link Map#keySet()}. The set's iterator will return the keys
376 * in their natural order (the order in which the enum constants
377 * are declared).
378 *
379 * @return a set view of the keys contained in this enum map
380 */
381 public Set<K> keySet() {
382 Set<K> ks = keySet;
383 if (ks != null)
384 return ks;
385 else
386 return keySet = new KeySet();
387 }
388
389 private class KeySet extends AbstractSet<K> {
390 public Iterator<K> iterator() {
391 return new KeyIterator();
392 }
393 public int size() {
394 return size;
395 }
396 public boolean contains(Object o) {
397 return containsKey(o);
398 }
399 public boolean remove(Object o) {
400 int oldSize = size;
401 EnumMap.this.remove(o);
402 return size != oldSize;
403 }
404 public void clear() {
405 EnumMap.this.clear();
406 }
407 }
408
409 /**
410 * Returns a {@link Collection} view of the values contained in this map.
411 * The returned collection obeys the general contract outlined in
412 * {@link Map#values()}. The collection's iterator will return the
413 * values in the order their corresponding keys appear in map,
414 * which is their natural order (the order in which the enum constants
415 * are declared).
416 *
417 * @return a collection view of the values contained in this map
418 */
419 public Collection<V> values() {
420 Collection<V> vs = values;
421 if (vs != null)
422 return vs;
423 else
424 return values = new Values();
425 }
426
427 private class Values extends AbstractCollection<V> {
428 public Iterator<V> iterator() {
429 return new ValueIterator();
430 }
431 public int size() {
432 return size;
433 }
434 public boolean contains(Object o) {
435 return containsValue(o);
436 }
437 public boolean remove(Object o) {
438 o = maskNull(o);
439
440 for (int i = 0; i < vals.length; i++) {
441 if (o.equals(vals[i])) {
442 vals[i] = null;
443 size--;
444 return true;
445 }
446 }
447 return false;
448 }
449 public void clear() {
450 EnumMap.this.clear();
451 }
452 }
453
454 /**
455 * Returns a {@link Set} view of the mappings contained in this map.
456 * The returned set obeys the general contract outlined in
457 * {@link Map#keySet()}. The set's iterator will return the
458 * mappings in the order their keys appear in map, which is their
459 * natural order (the order in which the enum constants are declared).
460 *
461 * @return a set view of the mappings contained in this enum map
462 */
463 public Set<Map.Entry<K,V>> entrySet() {
464 Set<Map.Entry<K,V>> es = entrySet;
465 if (es != null)
466 return es;
467 else
468 return entrySet = new EntrySet();
469 }
470
471 private class EntrySet extends AbstractSet<Map.Entry<K,V>> {
472 public Iterator<Map.Entry<K,V>> iterator() {
473 return new EntryIterator();
474 }
475
476 public boolean contains(Object o) {
477 if (!(o instanceof Map.Entry))
478 return false;
479 Map.Entry<?,?> entry = (Map.Entry<?,?>)o;
480 return containsMapping(entry.getKey(), entry.getValue());
481 }
482 public boolean remove(Object o) {
483 if (!(o instanceof Map.Entry))
484 return false;
485 Map.Entry<?,?> entry = (Map.Entry<?,?>)o;
486 return removeMapping(entry.getKey(), entry.getValue());
487 }
488 public int size() {
489 return size;
490 }
491 public void clear() {
492 EnumMap.this.clear();
493 }
494 public Object[] toArray() {
495 return fillEntryArray(new Object[size]);
496 }
497 @SuppressWarnings("unchecked")
498 public <T> T[] toArray(T[] a) {
499 int size = size();
500 if (a.length < size)
501 a = (T[])java.lang.reflect.Array
502 .newInstance(a.getClass().getComponentType(), size);
503 if (a.length > size)
504 a[size] = null;
505 return (T[]) fillEntryArray(a);
506 }
507 private Object[] fillEntryArray(Object[] a) {
508 int j = 0;
509 for (int i = 0; i < vals.length; i++)
510 if (vals[i] != null)
511 a[j++] = new AbstractMap.SimpleEntry<>(
512 keyUniverse[i], unmaskNull(vals[i]));
513 return a;
514 }
515 }
516
517 private abstract class EnumMapIterator<T> implements Iterator<T> {
518 // Lower bound on index of next element to return
519 int index = 0;
520
521 // Index of last returned element, or -1 if none
522 int lastReturnedIndex = -1;
523
524 public boolean hasNext() {
525 while (index < vals.length && vals[index] == null)
526 index++;
527 return index != vals.length;
528 }
529
530 public void remove() {
531 checkLastReturnedIndex();
532
533 if (vals[lastReturnedIndex] != null) {
534 vals[lastReturnedIndex] = null;
535 size--;
536 }
537 lastReturnedIndex = -1;
538 }
539
540 private void checkLastReturnedIndex() {
541 if (lastReturnedIndex < 0)
542 throw new IllegalStateException();
543 }
544 }
545
546 private class KeyIterator extends EnumMapIterator<K> {
547 public K next() {
548 if (!hasNext())
549 throw new NoSuchElementException();
550 lastReturnedIndex = index++;
551 return keyUniverse[lastReturnedIndex];
552 }
553 }
554
555 private class ValueIterator extends EnumMapIterator<V> {
556 public V next() {
557 if (!hasNext())
558 throw new NoSuchElementException();
559 lastReturnedIndex = index++;
560 return unmaskNull(vals[lastReturnedIndex]);
561 }
562 }
563
564 private class EntryIterator extends EnumMapIterator<Map.Entry<K,V>> {
565 private Entry lastReturnedEntry;
566
567 public Map.Entry<K,V> next() {
568 if (!hasNext())
569 throw new NoSuchElementException();
570 lastReturnedEntry = new Entry(index++);
571 return lastReturnedEntry;
572 }
573
574 public void remove() {
575 lastReturnedIndex =
576 ((null == lastReturnedEntry) ? -1 : lastReturnedEntry.index);
577 super.remove();
578 lastReturnedEntry.index = lastReturnedIndex;
579 lastReturnedEntry = null;
580 }
581
582 private class Entry implements Map.Entry<K,V> {
583 private int index;
584
585 private Entry(int index) {
586 this.index = index;
587 }
588
589 public K getKey() {
590 checkIndexForEntryUse();
591 return keyUniverse[index];
592 }
593
594 public V getValue() {
595 checkIndexForEntryUse();
596 return unmaskNull(vals[index]);
597 }
598
599 public V setValue(V value) {
600 checkIndexForEntryUse();
601 V oldValue = unmaskNull(vals[index]);
602 vals[index] = maskNull(value);
603 return oldValue;
604 }
605
606 public boolean equals(Object o) {
607 if (index < 0)
608 return o == this;
609
610 if (!(o instanceof Map.Entry))
611 return false;
612
613 Map.Entry<?,?> e = (Map.Entry<?,?>)o;
614 V ourValue = unmaskNull(vals[index]);
615 Object hisValue = e.getValue();
616 return (e.getKey() == keyUniverse[index] &&
617 (ourValue == hisValue ||
618 (ourValue != null && ourValue.equals(hisValue))));
619 }
620
621 public int hashCode() {
622 if (index < 0)
623 return super.hashCode();
624
625 return entryHashCode(index);
626 }
627
628 public String toString() {
629 if (index < 0)
630 return super.toString();
631
632 return keyUniverse[index] + "="
633 + unmaskNull(vals[index]);
634 }
635
636 private void checkIndexForEntryUse() {
637 if (index < 0)
638 throw new IllegalStateException("Entry was removed");
639 }
640 }
641 }
642
643 // Comparison and hashing
644
645 /**
646 * Compares the specified object with this map for equality. Returns
647 * <tt>true</tt> if the given object is also a map and the two maps
648 * represent the same mappings, as specified in the {@link
649 * Map#equals(Object)} contract.
650 *
651 * @param o the object to be compared for equality with this map
652 * @return <tt>true</tt> if the specified object is equal to this map
653 */
654 public boolean equals(Object o) {
655 if (this == o)
656 return true;
657 if (o instanceof EnumMap)
658 return equals((EnumMap<?,?>)o);
659 if (!(o instanceof Map))
660 return false;
661
662 Map<?,?> m = (Map<?,?>)o;
663 if (size != m.size())
664 return false;
665
666 for (int i = 0; i < keyUniverse.length; i++) {
667 if (null != vals[i]) {
668 K key = keyUniverse[i];
669 V value = unmaskNull(vals[i]);
670 if (null == value) {
671 if (!((null == m.get(key)) && m.containsKey(key)))
672 return false;
673 } else {
674 if (!value.equals(m.get(key)))
675 return false;
676 }
677 }
678 }
679
680 return true;
681 }
682
683 private boolean equals(EnumMap<?,?> em) {
684 if (em.keyType != keyType)
685 return size == 0 && em.size == 0;
686
687 // Key types match, compare each value
688 for (int i = 0; i < keyUniverse.length; i++) {
689 Object ourValue = vals[i];
690 Object hisValue = em.vals[i];
691 if (hisValue != ourValue &&
692 (hisValue == null || !hisValue.equals(ourValue)))
693 return false;
694 }
695 return true;
696 }
697
698 /**
699 * Returns the hash code value for this map. The hash code of a map is
700 * defined to be the sum of the hash codes of each entry in the map.
701 */
702 public int hashCode() {
703 int h = 0;
704
705 for (int i = 0; i < keyUniverse.length; i++) {
706 if (null != vals[i]) {
707 h += entryHashCode(i);
708 }
709 }
710
711 return h;
712 }
713
714 private int entryHashCode(int index) {
715 return (keyUniverse[index].hashCode() ^ vals[index].hashCode());
716 }
717
718 /**
719 * Returns a shallow copy of this enum map. (The values themselves
720 * are not cloned.
721 *
722 * @return a shallow copy of this enum map
723 */
724 @SuppressWarnings("unchecked")
725 public EnumMap<K, V> clone() {
726 EnumMap<K, V> result = null;
727 try {
728 result = (EnumMap<K, V>) super.clone();
729 } catch(CloneNotSupportedException e) {
730 throw new AssertionError();
731 }
732 result.vals = result.vals.clone();
733 result.entrySet = null;
734 return result;
735 }
736
737 /**
738 * Throws an exception if e is not of the correct type for this enum set.
739 */
740 private void typeCheck(K key) {
741 Class<?> keyClass = key.getClass();
742 if (keyClass != keyType && keyClass.getSuperclass() != keyType)
743 throw new ClassCastException(keyClass + " != " + keyType);
744 }
745
746 /**
747 * Returns all of the values comprising K.
748 * The result is uncloned, cached, and shared by all callers.
749 */
750 private static <K extends Enum<K>> K[] getKeyUniverse(Class<K> keyType) {
751 return SharedSecrets.getJavaLangAccess()
752 .getEnumConstantsShared(keyType);
753 }
754
755 private static final long serialVersionUID = 458661240069192865L;
756
757 /**
758 * Save the state of the <tt>EnumMap</tt> instance to a stream (i.e.,
759 * serialize it).
760 *
761 * @serialData The <i>size</i> of the enum map (the number of key-value
762 * mappings) is emitted (int), followed by the key (Object)
763 * and value (Object) for each key-value mapping represented
764 * by the enum map.
765 */
766 private void writeObject(java.io.ObjectOutputStream s)
767 throws java.io.IOException
768 {
769 // Write out the key type and any hidden stuff
770 s.defaultWriteObject();
771
772 // Write out size (number of Mappings)
773 s.writeInt(size);
774
775 // Write out keys and values (alternating)
776 int entriesToBeWritten = size;
777 for (int i = 0; entriesToBeWritten > 0; i++) {
778 if (null != vals[i]) {
779 s.writeObject(keyUniverse[i]);
780 s.writeObject(unmaskNull(vals[i]));
781 entriesToBeWritten--;
782 }
783 }
784 }
785
786 /**
787 * Reconstitute the <tt>EnumMap</tt> instance from a stream (i.e.,
788 * deserialize it).
789 */
790 @SuppressWarnings("unchecked")
791 private void readObject(java.io.ObjectInputStream s)
792 throws java.io.IOException, ClassNotFoundException
793 {
794 // Read in the key type and any hidden stuff
795 s.defaultReadObject();
796
797 keyUniverse = getKeyUniverse(keyType);
798 vals = new Object[keyUniverse.length];
799
800 // Read in size (number of Mappings)
801 int size = s.readInt();
802
803 // Read the keys and values, and put the mappings in the HashMap
804 for (int i = 0; i < size; i++) {
805 K key = (K) s.readObject();
806 V value = (V) s.readObject();
807 put(key, value);
808 }
809 }
810 }