[cvs] / jsr166 / src / main / java / util / HashMap.java Repository:
ViewVC logotype

Annotation of /jsr166/src/main/java/util/HashMap.java

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.3 - (view) (download)

1 : jsr166 1.1 /*
2 : jsr166 1.3 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 : jsr166 1.1 * 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.io.IOException;
29 :     import java.io.InvalidObjectException;
30 :     import java.io.Serializable;
31 :     import java.lang.reflect.ParameterizedType;
32 :     import java.lang.reflect.Type;
33 :     import java.util.function.BiConsumer;
34 :     import java.util.function.BiFunction;
35 :     import java.util.function.Consumer;
36 :     import java.util.function.Function;
37 : jsr166 1.3 import jdk.internal.misc.SharedSecrets;
38 : jsr166 1.1
39 :     /**
40 :     * Hash table based implementation of the {@code Map} interface. This
41 :     * implementation provides all of the optional map operations, and permits
42 :     * {@code null} values and the {@code null} key. (The {@code HashMap}
43 :     * class is roughly equivalent to {@code Hashtable}, except that it is
44 :     * unsynchronized and permits nulls.) This class makes no guarantees as to
45 :     * the order of the map; in particular, it does not guarantee that the order
46 :     * will remain constant over time.
47 :     *
48 :     * <p>This implementation provides constant-time performance for the basic
49 :     * operations ({@code get} and {@code put}), assuming the hash function
50 :     * disperses the elements properly among the buckets. Iteration over
51 :     * collection views requires time proportional to the "capacity" of the
52 :     * {@code HashMap} instance (the number of buckets) plus its size (the number
53 :     * of key-value mappings). Thus, it's very important not to set the initial
54 :     * capacity too high (or the load factor too low) if iteration performance is
55 :     * important.
56 :     *
57 :     * <p>An instance of {@code HashMap} has two parameters that affect its
58 :     * performance: <i>initial capacity</i> and <i>load factor</i>. The
59 :     * <i>capacity</i> is the number of buckets in the hash table, and the initial
60 :     * capacity is simply the capacity at the time the hash table is created. The
61 :     * <i>load factor</i> is a measure of how full the hash table is allowed to
62 :     * get before its capacity is automatically increased. When the number of
63 :     * entries in the hash table exceeds the product of the load factor and the
64 :     * current capacity, the hash table is <i>rehashed</i> (that is, internal data
65 :     * structures are rebuilt) so that the hash table has approximately twice the
66 :     * number of buckets.
67 :     *
68 :     * <p>As a general rule, the default load factor (.75) offers a good
69 :     * tradeoff between time and space costs. Higher values decrease the
70 :     * space overhead but increase the lookup cost (reflected in most of
71 :     * the operations of the {@code HashMap} class, including
72 :     * {@code get} and {@code put}). The expected number of entries in
73 :     * the map and its load factor should be taken into account when
74 :     * setting its initial capacity, so as to minimize the number of
75 :     * rehash operations. If the initial capacity is greater than the
76 :     * maximum number of entries divided by the load factor, no rehash
77 :     * operations will ever occur.
78 :     *
79 :     * <p>If many mappings are to be stored in a {@code HashMap}
80 :     * instance, creating it with a sufficiently large capacity will allow
81 :     * the mappings to be stored more efficiently than letting it perform
82 :     * automatic rehashing as needed to grow the table. Note that using
83 :     * many keys with the same {@code hashCode()} is a sure way to slow
84 :     * down performance of any hash table. To ameliorate impact, when keys
85 :     * are {@link Comparable}, this class may use comparison order among
86 :     * keys to help break ties.
87 :     *
88 :     * <p><strong>Note that this implementation is not synchronized.</strong>
89 :     * If multiple threads access a hash map concurrently, and at least one of
90 :     * the threads modifies the map structurally, it <i>must</i> be
91 :     * synchronized externally. (A structural modification is any operation
92 :     * that adds or deletes one or more mappings; merely changing the value
93 :     * associated with a key that an instance already contains is not a
94 :     * structural modification.) This is typically accomplished by
95 :     * synchronizing on some object that naturally encapsulates the map.
96 :     *
97 :     * If no such object exists, the map should be "wrapped" using the
98 :     * {@link Collections#synchronizedMap Collections.synchronizedMap}
99 :     * method. This is best done at creation time, to prevent accidental
100 :     * unsynchronized access to the map:<pre>
101 :     * Map m = Collections.synchronizedMap(new HashMap(...));</pre>
102 :     *
103 :     * <p>The iterators returned by all of this class's "collection view methods"
104 :     * are <i>fail-fast</i>: if the map is structurally modified at any time after
105 :     * the iterator is created, in any way except through the iterator's own
106 :     * {@code remove} method, the iterator will throw a
107 :     * {@link ConcurrentModificationException}. Thus, in the face of concurrent
108 :     * modification, the iterator fails quickly and cleanly, rather than risking
109 :     * arbitrary, non-deterministic behavior at an undetermined time in the
110 :     * future.
111 :     *
112 :     * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
113 :     * as it is, generally speaking, impossible to make any hard guarantees in the
114 :     * presence of unsynchronized concurrent modification. Fail-fast iterators
115 :     * throw {@code ConcurrentModificationException} on a best-effort basis.
116 :     * Therefore, it would be wrong to write a program that depended on this
117 :     * exception for its correctness: <i>the fail-fast behavior of iterators
118 :     * should be used only to detect bugs.</i>
119 :     *
120 :     * <p>This class is a member of the
121 :     * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
122 :     * Java Collections Framework</a>.
123 :     *
124 :     * @param <K> the type of keys maintained by this map
125 :     * @param <V> the type of mapped values
126 :     *
127 :     * @author Doug Lea
128 :     * @author Josh Bloch
129 :     * @author Arthur van Hoff
130 :     * @author Neal Gafter
131 :     * @see Object#hashCode()
132 :     * @see Collection
133 :     * @see Map
134 :     * @see TreeMap
135 :     * @see Hashtable
136 :     * @since 1.2
137 :     */
138 :     public class HashMap<K,V> extends AbstractMap<K,V>
139 :     implements Map<K,V>, Cloneable, Serializable {
140 :    
141 :     private static final long serialVersionUID = 362498820763181265L;
142 :    
143 :     /*
144 :     * Implementation notes.
145 :     *
146 :     * This map usually acts as a binned (bucketed) hash table, but
147 :     * when bins get too large, they are transformed into bins of
148 :     * TreeNodes, each structured similarly to those in
149 :     * java.util.TreeMap. Most methods try to use normal bins, but
150 :     * relay to TreeNode methods when applicable (simply by checking
151 :     * instanceof a node). Bins of TreeNodes may be traversed and
152 :     * used like any others, but additionally support faster lookup
153 :     * when overpopulated. However, since the vast majority of bins in
154 :     * normal use are not overpopulated, checking for existence of
155 :     * tree bins may be delayed in the course of table methods.
156 :     *
157 :     * Tree bins (i.e., bins whose elements are all TreeNodes) are
158 :     * ordered primarily by hashCode, but in the case of ties, if two
159 :     * elements are of the same "class C implements Comparable<C>",
160 :     * type then their compareTo method is used for ordering. (We
161 :     * conservatively check generic types via reflection to validate
162 :     * this -- see method comparableClassFor). The added complexity
163 :     * of tree bins is worthwhile in providing worst-case O(log n)
164 :     * operations when keys either have distinct hashes or are
165 :     * orderable, Thus, performance degrades gracefully under
166 :     * accidental or malicious usages in which hashCode() methods
167 :     * return values that are poorly distributed, as well as those in
168 :     * which many keys share a hashCode, so long as they are also
169 :     * Comparable. (If neither of these apply, we may waste about a
170 :     * factor of two in time and space compared to taking no
171 :     * precautions. But the only known cases stem from poor user
172 :     * programming practices that are already so slow that this makes
173 :     * little difference.)
174 :     *
175 :     * Because TreeNodes are about twice the size of regular nodes, we
176 :     * use them only when bins contain enough nodes to warrant use
177 :     * (see TREEIFY_THRESHOLD). And when they become too small (due to
178 :     * removal or resizing) they are converted back to plain bins. In
179 :     * usages with well-distributed user hashCodes, tree bins are
180 :     * rarely used. Ideally, under random hashCodes, the frequency of
181 :     * nodes in bins follows a Poisson distribution
182 :     * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
183 :     * parameter of about 0.5 on average for the default resizing
184 :     * threshold of 0.75, although with a large variance because of
185 :     * resizing granularity. Ignoring variance, the expected
186 :     * occurrences of list size k are (exp(-0.5) * pow(0.5, k) /
187 :     * factorial(k)). The first values are:
188 :     *
189 :     * 0: 0.60653066
190 :     * 1: 0.30326533
191 :     * 2: 0.07581633
192 :     * 3: 0.01263606
193 :     * 4: 0.00157952
194 :     * 5: 0.00015795
195 :     * 6: 0.00001316
196 :     * 7: 0.00000094
197 :     * 8: 0.00000006
198 :     * more: less than 1 in ten million
199 :     *
200 :     * The root of a tree bin is normally its first node. However,
201 :     * sometimes (currently only upon Iterator.remove), the root might
202 :     * be elsewhere, but can be recovered following parent links
203 :     * (method TreeNode.root()).
204 :     *
205 :     * All applicable internal methods accept a hash code as an
206 :     * argument (as normally supplied from a public method), allowing
207 :     * them to call each other without recomputing user hashCodes.
208 :     * Most internal methods also accept a "tab" argument, that is
209 :     * normally the current table, but may be a new or old one when
210 :     * resizing or converting.
211 :     *
212 :     * When bin lists are treeified, split, or untreeified, we keep
213 :     * them in the same relative access/traversal order (i.e., field
214 :     * Node.next) to better preserve locality, and to slightly
215 :     * simplify handling of splits and traversals that invoke
216 :     * iterator.remove. When using comparators on insertion, to keep a
217 :     * total ordering (or as close as is required here) across
218 :     * rebalancings, we compare classes and identityHashCodes as
219 :     * tie-breakers.
220 :     *
221 :     * The use and transitions among plain vs tree modes is
222 :     * complicated by the existence of subclass LinkedHashMap. See
223 :     * below for hook methods defined to be invoked upon insertion,
224 :     * removal and access that allow LinkedHashMap internals to
225 :     * otherwise remain independent of these mechanics. (This also
226 :     * requires that a map instance be passed to some utility methods
227 :     * that may create new nodes.)
228 :     *
229 :     * The concurrent-programming-like SSA-based coding style helps
230 :     * avoid aliasing errors amid all of the twisty pointer operations.
231 :     */
232 :    
233 :     /**
234 :     * The default initial capacity - MUST be a power of two.
235 :     */
236 :     static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
237 :    
238 :     /**
239 :     * The maximum capacity, used if a higher value is implicitly specified
240 :     * by either of the constructors with arguments.
241 :     * MUST be a power of two <= 1<<30.
242 :     */
243 :     static final int MAXIMUM_CAPACITY = 1 << 30;
244 :    
245 :     /**
246 :     * The load factor used when none specified in constructor.
247 :     */
248 :     static final float DEFAULT_LOAD_FACTOR = 0.75f;
249 :    
250 :     /**
251 :     * The bin count threshold for using a tree rather than list for a
252 :     * bin. Bins are converted to trees when adding an element to a
253 :     * bin with at least this many nodes. The value must be greater
254 :     * than 2 and should be at least 8 to mesh with assumptions in
255 :     * tree removal about conversion back to plain bins upon
256 :     * shrinkage.
257 :     */
258 :     static final int TREEIFY_THRESHOLD = 8;
259 :    
260 :     /**
261 :     * The bin count threshold for untreeifying a (split) bin during a
262 :     * resize operation. Should be less than TREEIFY_THRESHOLD, and at
263 :     * most 6 to mesh with shrinkage detection under removal.
264 :     */
265 :     static final int UNTREEIFY_THRESHOLD = 6;
266 :    
267 :     /**
268 :     * The smallest table capacity for which bins may be treeified.
269 :     * (Otherwise the table is resized if too many nodes in a bin.)
270 :     * Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
271 :     * between resizing and treeification thresholds.
272 :     */
273 :     static final int MIN_TREEIFY_CAPACITY = 64;
274 :    
275 :     /**
276 :     * Basic hash bin node, used for most entries. (See below for
277 :     * TreeNode subclass, and in LinkedHashMap for its Entry subclass.)
278 :     */
279 :     static class Node<K,V> implements Map.Entry<K,V> {
280 :     final int hash;
281 :     final K key;
282 :     V value;
283 :     Node<K,V> next;
284 :    
285 :     Node(int hash, K key, V value, Node<K,V> next) {
286 :     this.hash = hash;
287 :     this.key = key;
288 :     this.value = value;
289 :     this.next = next;
290 :     }
291 :    
292 :     public final K getKey() { return key; }
293 :     public final V getValue() { return value; }
294 :     public final String toString() { return key + "=" + value; }
295 :    
296 :     public final int hashCode() {
297 :     return Objects.hashCode(key) ^ Objects.hashCode(value);
298 :     }
299 :    
300 :     public final V setValue(V newValue) {
301 :     V oldValue = value;
302 :     value = newValue;
303 :     return oldValue;
304 :     }
305 :    
306 :     public final boolean equals(Object o) {
307 :     if (o == this)
308 :     return true;
309 :     if (o instanceof Map.Entry) {
310 :     Map.Entry<?,?> e = (Map.Entry<?,?>)o;
311 :     if (Objects.equals(key, e.getKey()) &&
312 :     Objects.equals(value, e.getValue()))
313 :     return true;
314 :     }
315 :     return false;
316 :     }
317 :     }
318 :    
319 :     /* ---------------- Static utilities -------------- */
320 :    
321 :     /**
322 :     * Computes key.hashCode() and spreads (XORs) higher bits of hash
323 :     * to lower. Because the table uses power-of-two masking, sets of
324 :     * hashes that vary only in bits above the current mask will
325 :     * always collide. (Among known examples are sets of Float keys
326 :     * holding consecutive whole numbers in small tables.) So we
327 :     * apply a transform that spreads the impact of higher bits
328 :     * downward. There is a tradeoff between speed, utility, and
329 :     * quality of bit-spreading. Because many common sets of hashes
330 :     * are already reasonably distributed (so don't benefit from
331 :     * spreading), and because we use trees to handle large sets of
332 :     * collisions in bins, we just XOR some shifted bits in the
333 :     * cheapest possible way to reduce systematic lossage, as well as
334 :     * to incorporate impact of the highest bits that would otherwise
335 :     * never be used in index calculations because of table bounds.
336 :     */
337 :     static final int hash(Object key) {
338 :     int h;
339 :     return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
340 :     }
341 :    
342 :     /**
343 :     * Returns x's Class if it is of the form "class C implements
344 :     * Comparable<C>", else null.
345 :     */
346 :     static Class<?> comparableClassFor(Object x) {
347 :     if (x instanceof Comparable) {
348 :     Class<?> c; Type[] ts, as; ParameterizedType p;
349 :     if ((c = x.getClass()) == String.class) // bypass checks
350 :     return c;
351 :     if ((ts = c.getGenericInterfaces()) != null) {
352 :     for (Type t : ts) {
353 :     if ((t instanceof ParameterizedType) &&
354 :     ((p = (ParameterizedType) t).getRawType() ==
355 :     Comparable.class) &&
356 :     (as = p.getActualTypeArguments()) != null &&
357 :     as.length == 1 && as[0] == c) // type arg is c
358 :     return c;
359 :     }
360 :     }
361 :     }
362 :     return null;
363 :     }
364 :    
365 :     /**
366 :     * Returns k.compareTo(x) if x matches kc (k's screened comparable
367 :     * class), else 0.
368 :     */
369 :     @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
370 :     static int compareComparables(Class<?> kc, Object k, Object x) {
371 :     return (x == null || x.getClass() != kc ? 0 :
372 :     ((Comparable)k).compareTo(x));
373 :     }
374 :    
375 :     /**
376 :     * Returns a power of two size for the given target capacity.
377 :     */
378 :     static final int tableSizeFor(int cap) {
379 :     int n = cap - 1;
380 :     n |= n >>> 1;
381 :     n |= n >>> 2;
382 :     n |= n >>> 4;
383 :     n |= n >>> 8;
384 :     n |= n >>> 16;
385 :     return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
386 :     }
387 :    
388 :     /* ---------------- Fields -------------- */
389 :    
390 :     /**
391 :     * The table, initialized on first use, and resized as
392 :     * necessary. When allocated, length is always a power of two.
393 :     * (We also tolerate length zero in some operations to allow
394 :     * bootstrapping mechanics that are currently not needed.)
395 :     */
396 :     transient Node<K,V>[] table;
397 :    
398 :     /**
399 :     * Holds cached entrySet(). Note that AbstractMap fields are used
400 :     * for keySet() and values().
401 :     */
402 :     transient Set<Map.Entry<K,V>> entrySet;
403 :    
404 :     /**
405 :     * The number of key-value mappings contained in this map.
406 :     */
407 :     transient int size;
408 :    
409 :     /**
410 :     * The number of times this HashMap has been structurally modified
411 :     * Structural modifications are those that change the number of mappings in
412 :     * the HashMap or otherwise modify its internal structure (e.g.,
413 :     * rehash). This field is used to make iterators on Collection-views of
414 :     * the HashMap fail-fast. (See ConcurrentModificationException).
415 :     */
416 :     transient int modCount;
417 :    
418 :     /**
419 :     * The next size value at which to resize (capacity * load factor).
420 :     *
421 :     * @serial
422 :     */
423 :     // (The javadoc description is true upon serialization.
424 :     // Additionally, if the table array has not been allocated, this
425 :     // field holds the initial array capacity, or zero signifying
426 :     // DEFAULT_INITIAL_CAPACITY.)
427 :     int threshold;
428 :    
429 :     /**
430 :     * The load factor for the hash table.
431 :     *
432 :     * @serial
433 :     */
434 :     final float loadFactor;
435 :    
436 :     /* ---------------- Public operations -------------- */
437 :    
438 :     /**
439 :     * Constructs an empty {@code HashMap} with the specified initial
440 :     * capacity and load factor.
441 :     *
442 :     * @param initialCapacity the initial capacity
443 :     * @param loadFactor the load factor
444 :     * @throws IllegalArgumentException if the initial capacity is negative
445 :     * or the load factor is nonpositive
446 :     */
447 :     public HashMap(int initialCapacity, float loadFactor) {
448 :     if (initialCapacity < 0)
449 :     throw new IllegalArgumentException("Illegal initial capacity: " +
450 :     initialCapacity);
451 :     if (initialCapacity > MAXIMUM_CAPACITY)
452 :     initialCapacity = MAXIMUM_CAPACITY;
453 :     if (loadFactor <= 0 || Float.isNaN(loadFactor))
454 :     throw new IllegalArgumentException("Illegal load factor: " +
455 :     loadFactor);
456 :     this.loadFactor = loadFactor;
457 :     this.threshold = tableSizeFor(initialCapacity);
458 :     }
459 :    
460 :     /**
461 :     * Constructs an empty {@code HashMap} with the specified initial
462 :     * capacity and the default load factor (0.75).
463 :     *
464 :     * @param initialCapacity the initial capacity.
465 :     * @throws IllegalArgumentException if the initial capacity is negative.
466 :     */
467 :     public HashMap(int initialCapacity) {
468 :     this(initialCapacity, DEFAULT_LOAD_FACTOR);
469 :     }
470 :    
471 :     /**
472 :     * Constructs an empty {@code HashMap} with the default initial capacity
473 :     * (16) and the default load factor (0.75).
474 :     */
475 :     public HashMap() {
476 :     this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
477 :     }
478 :    
479 :     /**
480 :     * Constructs a new {@code HashMap} with the same mappings as the
481 :     * specified {@code Map}. The {@code HashMap} is created with
482 :     * default load factor (0.75) and an initial capacity sufficient to
483 :     * hold the mappings in the specified {@code Map}.
484 :     *
485 :     * @param m the map whose mappings are to be placed in this map
486 :     * @throws NullPointerException if the specified map is null
487 :     */
488 :     public HashMap(Map<? extends K, ? extends V> m) {
489 :     this.loadFactor = DEFAULT_LOAD_FACTOR;
490 :     putMapEntries(m, false);
491 :     }
492 :    
493 :     /**
494 :     * Implements Map.putAll and Map constructor.
495 :     *
496 :     * @param m the map
497 :     * @param evict false when initially constructing this map, else
498 :     * true (relayed to method afterNodeInsertion).
499 :     */
500 :     final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
501 :     int s = m.size();
502 :     if (s > 0) {
503 :     if (table == null) { // pre-size
504 :     float ft = ((float)s / loadFactor) + 1.0F;
505 :     int t = ((ft < (float)MAXIMUM_CAPACITY) ?
506 :     (int)ft : MAXIMUM_CAPACITY);
507 :     if (t > threshold)
508 :     threshold = tableSizeFor(t);
509 :     }
510 :     else if (s > threshold)
511 :     resize();
512 :     for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
513 :     K key = e.getKey();
514 :     V value = e.getValue();
515 :     putVal(hash(key), key, value, false, evict);
516 :     }
517 :     }
518 :     }
519 :    
520 :     /**
521 :     * Returns the number of key-value mappings in this map.
522 :     *
523 :     * @return the number of key-value mappings in this map
524 :     */
525 :     public int size() {
526 :     return size;
527 :     }
528 :    
529 :     /**
530 :     * Returns {@code true} if this map contains no key-value mappings.
531 :     *
532 :     * @return {@code true} if this map contains no key-value mappings
533 :     */
534 :     public boolean isEmpty() {
535 :     return size == 0;
536 :     }
537 :    
538 :     /**
539 :     * Returns the value to which the specified key is mapped,
540 :     * or {@code null} if this map contains no mapping for the key.
541 :     *
542 :     * <p>More formally, if this map contains a mapping from a key
543 :     * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
544 :     * key.equals(k))}, then this method returns {@code v}; otherwise
545 :     * it returns {@code null}. (There can be at most one such mapping.)
546 :     *
547 :     * <p>A return value of {@code null} does not <i>necessarily</i>
548 :     * indicate that the map contains no mapping for the key; it's also
549 :     * possible that the map explicitly maps the key to {@code null}.
550 :     * The {@link #containsKey containsKey} operation may be used to
551 :     * distinguish these two cases.
552 :     *
553 :     * @see #put(Object, Object)
554 :     */
555 :     public V get(Object key) {
556 :     Node<K,V> e;
557 :     return (e = getNode(hash(key), key)) == null ? null : e.value;
558 :     }
559 :    
560 :     /**
561 :     * Implements Map.get and related methods.
562 :     *
563 :     * @param hash hash for key
564 :     * @param key the key
565 :     * @return the node, or null if none
566 :     */
567 :     final Node<K,V> getNode(int hash, Object key) {
568 :     Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
569 :     if ((tab = table) != null && (n = tab.length) > 0 &&
570 :     (first = tab[(n - 1) & hash]) != null) {
571 :     if (first.hash == hash && // always check first node
572 :     ((k = first.key) == key || (key != null && key.equals(k))))
573 :     return first;
574 :     if ((e = first.next) != null) {
575 :     if (first instanceof TreeNode)
576 :     return ((TreeNode<K,V>)first).getTreeNode(hash, key);
577 :     do {
578 :     if (e.hash == hash &&
579 :     ((k = e.key) == key || (key != null && key.equals(k))))
580 :     return e;
581 :     } while ((e = e.next) != null);
582 :     }
583 :     }
584 :     return null;
585 :     }
586 :    
587 :     /**
588 :     * Returns {@code true} if this map contains a mapping for the
589 :     * specified key.
590 :     *
591 :     * @param key The key whose presence in this map is to be tested
592 :     * @return {@code true} if this map contains a mapping for the specified
593 :     * key.
594 :     */
595 :     public boolean containsKey(Object key) {
596 :     return getNode(hash(key), key) != null;
597 :     }
598 :    
599 :     /**
600 :     * Associates the specified value with the specified key in this map.
601 :     * If the map previously contained a mapping for the key, the old
602 :     * value is replaced.
603 :     *
604 :     * @param key key with which the specified value is to be associated
605 :     * @param value value to be associated with the specified key
606 :     * @return the previous value associated with {@code key}, or
607 :     * {@code null} if there was no mapping for {@code key}.
608 :     * (A {@code null} return can also indicate that the map
609 :     * previously associated {@code null} with {@code key}.)
610 :     */
611 :     public V put(K key, V value) {
612 :     return putVal(hash(key), key, value, false, true);
613 :     }
614 :    
615 :     /**
616 :     * Implements Map.put and related methods.
617 :     *
618 :     * @param hash hash for key
619 :     * @param key the key
620 :     * @param value the value to put
621 :     * @param onlyIfAbsent if true, don't change existing value
622 :     * @param evict if false, the table is in creation mode.
623 :     * @return previous value, or null if none
624 :     */
625 :     final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
626 :     boolean evict) {
627 :     Node<K,V>[] tab; Node<K,V> p; int n, i;
628 :     if ((tab = table) == null || (n = tab.length) == 0)
629 :     n = (tab = resize()).length;
630 :     if ((p = tab[i = (n - 1) & hash]) == null)
631 :     tab[i] = newNode(hash, key, value, null);
632 :     else {
633 :     Node<K,V> e; K k;
634 :     if (p.hash == hash &&
635 :     ((k = p.key) == key || (key != null && key.equals(k))))
636 :     e = p;
637 :     else if (p instanceof TreeNode)
638 :     e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
639 :     else {
640 :     for (int binCount = 0; ; ++binCount) {
641 :     if ((e = p.next) == null) {
642 :     p.next = newNode(hash, key, value, null);
643 :     if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
644 :     treeifyBin(tab, hash);
645 :     break;
646 :     }
647 :     if (e.hash == hash &&
648 :     ((k = e.key) == key || (key != null && key.equals(k))))
649 :     break;
650 :     p = e;
651 :     }
652 :     }
653 :     if (e != null) { // existing mapping for key
654 :     V oldValue = e.value;
655 :     if (!onlyIfAbsent || oldValue == null)
656 :     e.value = value;
657 :     afterNodeAccess(e);
658 :     return oldValue;
659 :     }
660 :     }
661 :     ++modCount;
662 :     if (++size > threshold)
663 :     resize();
664 :     afterNodeInsertion(evict);
665 :     return null;
666 :     }
667 :    
668 :     /**
669 :     * Initializes or doubles table size. If null, allocates in
670 :     * accord with initial capacity target held in field threshold.
671 :     * Otherwise, because we are using power-of-two expansion, the
672 :     * elements from each bin must either stay at same index, or move
673 :     * with a power of two offset in the new table.
674 :     *
675 :     * @return the table
676 :     */
677 :     final Node<K,V>[] resize() {
678 :     Node<K,V>[] oldTab = table;
679 :     int oldCap = (oldTab == null) ? 0 : oldTab.length;
680 :     int oldThr = threshold;
681 :     int newCap, newThr = 0;
682 :     if (oldCap > 0) {
683 :     if (oldCap >= MAXIMUM_CAPACITY) {
684 :     threshold = Integer.MAX_VALUE;
685 :     return oldTab;
686 :     }
687 :     else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
688 :     oldCap >= DEFAULT_INITIAL_CAPACITY)
689 :     newThr = oldThr << 1; // double threshold
690 :     }
691 :     else if (oldThr > 0) // initial capacity was placed in threshold
692 :     newCap = oldThr;
693 :     else { // zero initial threshold signifies using defaults
694 :     newCap = DEFAULT_INITIAL_CAPACITY;
695 :     newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
696 :     }
697 :     if (newThr == 0) {
698 :     float ft = (float)newCap * loadFactor;
699 :     newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
700 :     (int)ft : Integer.MAX_VALUE);
701 :     }
702 :     threshold = newThr;
703 :     @SuppressWarnings({"rawtypes","unchecked"})
704 :     Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
705 :     table = newTab;
706 :     if (oldTab != null) {
707 :     for (int j = 0; j < oldCap; ++j) {
708 :     Node<K,V> e;
709 :     if ((e = oldTab[j]) != null) {
710 :     oldTab[j] = null;
711 :     if (e.next == null)
712 :     newTab[e.hash & (newCap - 1)] = e;
713 :     else if (e instanceof TreeNode)
714 :     ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
715 :     else { // preserve order
716 :     Node<K,V> loHead = null, loTail = null;
717 :     Node<K,V> hiHead = null, hiTail = null;
718 :     Node<K,V> next;
719 :     do {
720 :     next = e.next;
721 :     if ((e.hash & oldCap) == 0) {
722 :     if (loTail == null)
723 :     loHead = e;
724 :     else
725 :     loTail.next = e;
726 :     loTail = e;
727 :     }
728 :     else {
729 :     if (hiTail == null)
730 :     hiHead = e;
731 :     else
732 :     hiTail.next = e;
733 :     hiTail = e;
734 :     }
735 :     } while ((e = next) != null);
736 :     if (loTail != null) {
737 :     loTail.next = null;
738 :     newTab[j] = loHead;
739 :     }
740 :     if (hiTail != null) {
741 :     hiTail.next = null;
742 :     newTab[j + oldCap] = hiHead;
743 :     }
744 :     }
745 :     }
746 :     }
747 :     }
748 :     return newTab;
749 :     }
750 :    
751 :     /**
752 :     * Replaces all linked nodes in bin at index for given hash unless
753 :     * table is too small, in which case resizes instead.
754 :     */
755 :     final void treeifyBin(Node<K,V>[] tab, int hash) {
756 :     int n, index; Node<K,V> e;
757 :     if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
758 :     resize();
759 :     else if ((e = tab[index = (n - 1) & hash]) != null) {
760 :     TreeNode<K,V> hd = null, tl = null;
761 :     do {
762 :     TreeNode<K,V> p = replacementTreeNode(e, null);
763 :     if (tl == null)
764 :     hd = p;
765 :     else {
766 :     p.prev = tl;
767 :     tl.next = p;
768 :     }
769 :     tl = p;
770 :     } while ((e = e.next) != null);
771 :     if ((tab[index] = hd) != null)
772 :     hd.treeify(tab);
773 :     }
774 :     }
775 :    
776 :     /**
777 :     * Copies all of the mappings from the specified map to this map.
778 :     * These mappings will replace any mappings that this map had for
779 :     * any of the keys currently in the specified map.
780 :     *
781 :     * @param m mappings to be stored in this map
782 :     * @throws NullPointerException if the specified map is null
783 :     */
784 :     public void putAll(Map<? extends K, ? extends V> m) {
785 :     putMapEntries(m, true);
786 :     }
787 :    
788 :     /**
789 :     * Removes the mapping for the specified key from this map if present.
790 :     *
791 :     * @param key key whose mapping is to be removed from the map
792 :     * @return the previous value associated with {@code key}, or
793 :     * {@code null} if there was no mapping for {@code key}.
794 :     * (A {@code null} return can also indicate that the map
795 :     * previously associated {@code null} with {@code key}.)
796 :     */
797 :     public V remove(Object key) {
798 :     Node<K,V> e;
799 :     return (e = removeNode(hash(key), key, null, false, true)) == null ?
800 :     null : e.value;
801 :     }
802 :    
803 :     /**
804 :     * Implements Map.remove and related methods.
805 :     *
806 :     * @param hash hash for key
807 :     * @param key the key
808 :     * @param value the value to match if matchValue, else ignored
809 :     * @param matchValue if true only remove if value is equal
810 :     * @param movable if false do not move other nodes while removing
811 :     * @return the node, or null if none
812 :     */
813 :     final Node<K,V> removeNode(int hash, Object key, Object value,
814 :     boolean matchValue, boolean movable) {
815 :     Node<K,V>[] tab; Node<K,V> p; int n, index;
816 :     if ((tab = table) != null && (n = tab.length) > 0 &&
817 :     (p = tab[index = (n - 1) & hash]) != null) {
818 :     Node<K,V> node = null, e; K k; V v;
819 :     if (p.hash == hash &&
820 :     ((k = p.key) == key || (key != null && key.equals(k))))
821 :     node = p;
822 :     else if ((e = p.next) != null) {
823 :     if (p instanceof TreeNode)
824 :     node = ((TreeNode<K,V>)p).getTreeNode(hash, key);
825 :     else {
826 :     do {
827 :     if (e.hash == hash &&
828 :     ((k = e.key) == key ||
829 :     (key != null && key.equals(k)))) {
830 :     node = e;
831 :     break;
832 :     }
833 :     p = e;
834 :     } while ((e = e.next) != null);
835 :     }
836 :     }
837 :     if (node != null && (!matchValue || (v = node.value) == value ||
838 :     (value != null && value.equals(v)))) {
839 :     if (node instanceof TreeNode)
840 :     ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable);
841 :     else if (node == p)
842 :     tab[index] = node.next;
843 :     else
844 :     p.next = node.next;
845 :     ++modCount;
846 :     --size;
847 :     afterNodeRemoval(node);
848 :     return node;
849 :     }
850 :     }
851 :     return null;
852 :     }
853 :    
854 :     /**
855 :     * Removes all of the mappings from this map.
856 :     * The map will be empty after this call returns.
857 :     */
858 :     public void clear() {
859 :     Node<K,V>[] tab;
860 :     modCount++;
861 :     if ((tab = table) != null && size > 0) {
862 :     size = 0;
863 :     for (int i = 0; i < tab.length; ++i)
864 :     tab[i] = null;
865 :     }
866 :     }
867 :    
868 :     /**
869 :     * Returns {@code true} if this map maps one or more keys to the
870 :     * specified value.
871 :     *
872 :     * @param value value whose presence in this map is to be tested
873 :     * @return {@code true} if this map maps one or more keys to the
874 :     * specified value
875 :     */
876 :     public boolean containsValue(Object value) {
877 :     Node<K,V>[] tab; V v;
878 :     if ((tab = table) != null && size > 0) {
879 :     for (Node<K,V> e : tab) {
880 :     for (; e != null; e = e.next) {
881 :     if ((v = e.value) == value ||
882 :     (value != null && value.equals(v)))
883 :     return true;
884 :     }
885 :     }
886 :     }
887 :     return false;
888 :     }
889 :    
890 :     /**
891 :     * Returns a {@link Set} view of the keys contained in this map.
892 :     * The set is backed by the map, so changes to the map are
893 :     * reflected in the set, and vice-versa. If the map is modified
894 :     * while an iteration over the set is in progress (except through
895 :     * the iterator's own {@code remove} operation), the results of
896 :     * the iteration are undefined. The set supports element removal,
897 :     * which removes the corresponding mapping from the map, via the
898 :     * {@code Iterator.remove}, {@code Set.remove},
899 :     * {@code removeAll}, {@code retainAll}, and {@code clear}
900 :     * operations. It does not support the {@code add} or {@code addAll}
901 :     * operations.
902 :     *
903 :     * @return a set view of the keys contained in this map
904 :     */
905 :     public Set<K> keySet() {
906 :     Set<K> ks = keySet;
907 :     if (ks == null) {
908 :     ks = new KeySet();
909 :     keySet = ks;
910 :     }
911 :     return ks;
912 :     }
913 :    
914 :     final class KeySet extends AbstractSet<K> {
915 :     public final int size() { return size; }
916 :     public final void clear() { HashMap.this.clear(); }
917 :     public final Iterator<K> iterator() { return new KeyIterator(); }
918 :     public final boolean contains(Object o) { return containsKey(o); }
919 :     public final boolean remove(Object key) {
920 :     return removeNode(hash(key), key, null, false, true) != null;
921 :     }
922 :     public final Spliterator<K> spliterator() {
923 :     return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
924 :     }
925 :     public final void forEach(Consumer<? super K> action) {
926 :     Node<K,V>[] tab;
927 :     if (action == null)
928 :     throw new NullPointerException();
929 :     if (size > 0 && (tab = table) != null) {
930 :     int mc = modCount;
931 :     for (Node<K,V> e : tab) {
932 :     for (; e != null; e = e.next)
933 :     action.accept(e.key);
934 :     }
935 :     if (modCount != mc)
936 :     throw new ConcurrentModificationException();
937 :     }
938 :     }
939 :     }
940 :    
941 :     /**
942 :     * Returns a {@link Collection} view of the values contained in this map.
943 :     * The collection is backed by the map, so changes to the map are
944 :     * reflected in the collection, and vice-versa. If the map is
945 :     * modified while an iteration over the collection is in progress
946 :     * (except through the iterator's own {@code remove} operation),
947 :     * the results of the iteration are undefined. The collection
948 :     * supports element removal, which removes the corresponding
949 :     * mapping from the map, via the {@code Iterator.remove},
950 :     * {@code Collection.remove}, {@code removeAll},
951 :     * {@code retainAll} and {@code clear} operations. It does not
952 :     * support the {@code add} or {@code addAll} operations.
953 :     *
954 :     * @return a view of the values contained in this map
955 :     */
956 :     public Collection<V> values() {
957 :     Collection<V> vs = values;
958 :     if (vs == null) {
959 :     vs = new Values();
960 :     values = vs;
961 :     }
962 :     return vs;
963 :     }
964 :    
965 :     final class Values extends AbstractCollection<V> {
966 :     public final int size() { return size; }
967 :     public final void clear() { HashMap.this.clear(); }
968 :     public final Iterator<V> iterator() { return new ValueIterator(); }
969 :     public final boolean contains(Object o) { return containsValue(o); }
970 :     public final Spliterator<V> spliterator() {
971 :     return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
972 :     }
973 :     public final void forEach(Consumer<? super V> action) {
974 :     Node<K,V>[] tab;
975 :     if (action == null)
976 :     throw new NullPointerException();
977 :     if (size > 0 && (tab = table) != null) {
978 :     int mc = modCount;
979 :     for (Node<K,V> e : tab) {
980 :     for (; e != null; e = e.next)
981 :     action.accept(e.value);
982 :     }
983 :     if (modCount != mc)
984 :     throw new ConcurrentModificationException();
985 :     }
986 :     }
987 :     }
988 :    
989 :     /**
990 :     * Returns a {@link Set} view of the mappings contained in this map.
991 :     * The set is backed by the map, so changes to the map are
992 :     * reflected in the set, and vice-versa. If the map is modified
993 :     * while an iteration over the set is in progress (except through
994 :     * the iterator's own {@code remove} operation, or through the
995 :     * {@code setValue} operation on a map entry returned by the
996 :     * iterator) the results of the iteration are undefined. The set
997 :     * supports element removal, which removes the corresponding
998 :     * mapping from the map, via the {@code Iterator.remove},
999 :     * {@code Set.remove}, {@code removeAll}, {@code retainAll} and
1000 :     * {@code clear} operations. It does not support the
1001 :     * {@code add} or {@code addAll} operations.
1002 :     *
1003 :     * @return a set view of the mappings contained in this map
1004 :     */
1005 :     public Set<Map.Entry<K,V>> entrySet() {
1006 :     Set<Map.Entry<K,V>> es;
1007 :     return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
1008 :     }
1009 :    
1010 :     final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1011 :     public final int size() { return size; }
1012 :     public final void clear() { HashMap.this.clear(); }
1013 :     public final Iterator<Map.Entry<K,V>> iterator() {
1014 :     return new EntryIterator();
1015 :     }
1016 :     public final boolean contains(Object o) {
1017 :     if (!(o instanceof Map.Entry))
1018 :     return false;
1019 :     Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1020 :     Object key = e.getKey();
1021 :     Node<K,V> candidate = getNode(hash(key), key);
1022 :     return candidate != null && candidate.equals(e);
1023 :     }
1024 :     public final boolean remove(Object o) {
1025 :     if (o instanceof Map.Entry) {
1026 :     Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1027 :     Object key = e.getKey();
1028 :     Object value = e.getValue();
1029 :     return removeNode(hash(key), key, value, true, true) != null;
1030 :     }
1031 :     return false;
1032 :     }
1033 :     public final Spliterator<Map.Entry<K,V>> spliterator() {
1034 :     return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
1035 :     }
1036 :     public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1037 :     Node<K,V>[] tab;
1038 :     if (action == null)
1039 :     throw new NullPointerException();
1040 :     if (size > 0 && (tab = table) != null) {
1041 :     int mc = modCount;
1042 :     for (Node<K,V> e : tab) {
1043 :     for (; e != null; e = e.next)
1044 :     action.accept(e);
1045 :     }
1046 :     if (modCount != mc)
1047 :     throw new ConcurrentModificationException();
1048 :     }
1049 :     }
1050 :     }
1051 :    
1052 :     // Overrides of JDK8 Map extension methods
1053 :    
1054 :     @Override
1055 :     public V getOrDefault(Object key, V defaultValue) {
1056 :     Node<K,V> e;
1057 :     return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1058 :     }
1059 :    
1060 :     @Override
1061 :     public V putIfAbsent(K key, V value) {
1062 :     return putVal(hash(key), key, value, true, true);
1063 :     }
1064 :    
1065 :     @Override
1066 :     public boolean remove(Object key, Object value) {
1067 :     return removeNode(hash(key), key, value, true, true) != null;
1068 :     }
1069 :    
1070 :     @Override
1071 :     public boolean replace(K key, V oldValue, V newValue) {
1072 :     Node<K,V> e; V v;
1073 :     if ((e = getNode(hash(key), key)) != null &&
1074 :     ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1075 :     e.value = newValue;
1076 :     afterNodeAccess(e);
1077 :     return true;
1078 :     }
1079 :     return false;
1080 :     }
1081 :    
1082 :     @Override
1083 :     public V replace(K key, V value) {
1084 :     Node<K,V> e;
1085 :     if ((e = getNode(hash(key), key)) != null) {
1086 :     V oldValue = e.value;
1087 :     e.value = value;
1088 :     afterNodeAccess(e);
1089 :     return oldValue;
1090 :     }
1091 :     return null;
1092 :     }
1093 :    
1094 :     /**
1095 :     * {@inheritDoc}
1096 :     *
1097 :     * <p>This method will, on a best-effort basis, throw a
1098 :     * {@link ConcurrentModificationException} if it is detected that the
1099 :     * mapping function modifies this map during computation.
1100 :     *
1101 :     * @throws ConcurrentModificationException if it is detected that the
1102 :     * mapping function modified this map
1103 :     */
1104 :     @Override
1105 :     public V computeIfAbsent(K key,
1106 :     Function<? super K, ? extends V> mappingFunction) {
1107 :     if (mappingFunction == null)
1108 :     throw new NullPointerException();
1109 :     int hash = hash(key);
1110 :     Node<K,V>[] tab; Node<K,V> first; int n, i;
1111 :     int binCount = 0;
1112 :     TreeNode<K,V> t = null;
1113 :     Node<K,V> old = null;
1114 :     if (size > threshold || (tab = table) == null ||
1115 :     (n = tab.length) == 0)
1116 :     n = (tab = resize()).length;
1117 :     if ((first = tab[i = (n - 1) & hash]) != null) {
1118 :     if (first instanceof TreeNode)
1119 :     old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1120 :     else {
1121 :     Node<K,V> e = first; K k;
1122 :     do {
1123 :     if (e.hash == hash &&
1124 :     ((k = e.key) == key || (key != null && key.equals(k)))) {
1125 :     old = e;
1126 :     break;
1127 :     }
1128 :     ++binCount;
1129 :     } while ((e = e.next) != null);
1130 :     }
1131 :     V oldValue;
1132 :     if (old != null && (oldValue = old.value) != null) {
1133 :     afterNodeAccess(old);
1134 :     return oldValue;
1135 :     }
1136 :     }
1137 :     int mc = modCount;
1138 :     V v = mappingFunction.apply(key);
1139 :     if (mc != modCount) { throw new ConcurrentModificationException(); }
1140 :     if (v == null) {
1141 :     return null;
1142 :     } else if (old != null) {
1143 :     old.value = v;
1144 :     afterNodeAccess(old);
1145 :     return v;
1146 :     }
1147 :     else if (t != null)
1148 :     t.putTreeVal(this, tab, hash, key, v);
1149 :     else {
1150 :     tab[i] = newNode(hash, key, v, first);
1151 :     if (binCount >= TREEIFY_THRESHOLD - 1)
1152 :     treeifyBin(tab, hash);
1153 :     }
1154 :     modCount = mc + 1;
1155 :     ++size;
1156 :     afterNodeInsertion(true);
1157 :     return v;
1158 :     }
1159 :    
1160 :     /**
1161 :     * {@inheritDoc}
1162 :     *
1163 :     * <p>This method will, on a best-effort basis, throw a
1164 :     * {@link ConcurrentModificationException} if it is detected that the
1165 :     * remapping function modifies this map during computation.
1166 :     *
1167 :     * @throws ConcurrentModificationException if it is detected that the
1168 :     * remapping function modified this map
1169 :     */
1170 :     @Override
1171 :     public V computeIfPresent(K key,
1172 :     BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1173 :     if (remappingFunction == null)
1174 :     throw new NullPointerException();
1175 :     Node<K,V> e; V oldValue;
1176 :     int hash = hash(key);
1177 :     if ((e = getNode(hash, key)) != null &&
1178 :     (oldValue = e.value) != null) {
1179 :     int mc = modCount;
1180 :     V v = remappingFunction.apply(key, oldValue);
1181 :     if (mc != modCount) { throw new ConcurrentModificationException(); }
1182 :     if (v != null) {
1183 :     e.value = v;
1184 :     afterNodeAccess(e);
1185 :     return v;
1186 :     }
1187 :     else
1188 :     removeNode(hash, key, null, false, true);
1189 :     }
1190 :     return null;
1191 :     }
1192 :    
1193 :     /**
1194 :     * {@inheritDoc}
1195 :     *
1196 :     * <p>This method will, on a best-effort basis, throw a
1197 :     * {@link ConcurrentModificationException} if it is detected that the
1198 :     * remapping function modifies this map during computation.
1199 :     *
1200 :     * @throws ConcurrentModificationException if it is detected that the
1201 :     * remapping function modified this map
1202 :     */
1203 :     @Override
1204 :     public V compute(K key,
1205 :     BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1206 :     if (remappingFunction == null)
1207 :     throw new NullPointerException();
1208 :     int hash = hash(key);
1209 :     Node<K,V>[] tab; Node<K,V> first; int n, i;
1210 :     int binCount = 0;
1211 :     TreeNode<K,V> t = null;
1212 :     Node<K,V> old = null;
1213 :     if (size > threshold || (tab = table) == null ||
1214 :     (n = tab.length) == 0)
1215 :     n = (tab = resize()).length;
1216 :     if ((first = tab[i = (n - 1) & hash]) != null) {
1217 :     if (first instanceof TreeNode)
1218 :     old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1219 :     else {
1220 :     Node<K,V> e = first; K k;
1221 :     do {
1222 :     if (e.hash == hash &&
1223 :     ((k = e.key) == key || (key != null && key.equals(k)))) {
1224 :     old = e;
1225 :     break;
1226 :     }
1227 :     ++binCount;
1228 :     } while ((e = e.next) != null);
1229 :     }
1230 :     }
1231 :     V oldValue = (old == null) ? null : old.value;
1232 :     int mc = modCount;
1233 :     V v = remappingFunction.apply(key, oldValue);
1234 :     if (mc != modCount) { throw new ConcurrentModificationException(); }
1235 :     if (old != null) {
1236 :     if (v != null) {
1237 :     old.value = v;
1238 :     afterNodeAccess(old);
1239 :     }
1240 :     else
1241 :     removeNode(hash, key, null, false, true);
1242 :     }
1243 :     else if (v != null) {
1244 :     if (t != null)
1245 :     t.putTreeVal(this, tab, hash, key, v);
1246 :     else {
1247 :     tab[i] = newNode(hash, key, v, first);
1248 :     if (binCount >= TREEIFY_THRESHOLD - 1)
1249 :     treeifyBin(tab, hash);
1250 :     }
1251 :     modCount = mc + 1;
1252 :     ++size;
1253 :     afterNodeInsertion(true);
1254 :     }
1255 :     return v;
1256 :     }
1257 :    
1258 :     /**
1259 :     * {@inheritDoc}
1260 :     *
1261 :     * <p>This method will, on a best-effort basis, throw a
1262 :     * {@link ConcurrentModificationException} if it is detected that the
1263 :     * remapping function modifies this map during computation.
1264 :     *
1265 :     * @throws ConcurrentModificationException if it is detected that the
1266 :     * remapping function modified this map
1267 :     */
1268 :     @Override
1269 :     public V merge(K key, V value,
1270 :     BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1271 :     if (value == null)
1272 :     throw new NullPointerException();
1273 :     if (remappingFunction == null)
1274 :     throw new NullPointerException();
1275 :     int hash = hash(key);
1276 :     Node<K,V>[] tab; Node<K,V> first; int n, i;
1277 :     int binCount = 0;
1278 :     TreeNode<K,V> t = null;
1279 :     Node<K,V> old = null;
1280 :     if (size > threshold || (tab = table) == null ||
1281 :     (n = tab.length) == 0)
1282 :     n = (tab = resize()).length;
1283 :     if ((first = tab[i = (n - 1) & hash]) != null) {
1284 :     if (first instanceof TreeNode)
1285 :     old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1286 :     else {
1287 :     Node<K,V> e = first; K k;
1288 :     do {
1289 :     if (e.hash == hash &&
1290 :     ((k = e.key) == key || (key != null && key.equals(k)))) {
1291 :     old = e;
1292 :     break;
1293 :     }
1294 :     ++binCount;
1295 :     } while ((e = e.next) != null);
1296 :     }
1297 :     }
1298 :     if (old != null) {
1299 :     V v;
1300 :     if (old.value != null) {
1301 :     int mc = modCount;
1302 :     v = remappingFunction.apply(old.value, value);
1303 :     if (mc != modCount) {
1304 :     throw new ConcurrentModificationException();
1305 :     }
1306 :     } else {
1307 :     v = value;
1308 :     }
1309 :     if (v != null) {
1310 :     old.value = v;
1311 :     afterNodeAccess(old);
1312 :     }
1313 :     else
1314 :     removeNode(hash, key, null, false, true);
1315 :     return v;
1316 :     }
1317 :     if (value != null) {
1318 :     if (t != null)
1319 :     t.putTreeVal(this, tab, hash, key, value);
1320 :     else {
1321 :     tab[i] = newNode(hash, key, value, first);
1322 :     if (binCount >= TREEIFY_THRESHOLD - 1)
1323 :     treeifyBin(tab, hash);
1324 :     }
1325 :     ++modCount;
1326 :     ++size;
1327 :     afterNodeInsertion(true);
1328 :     }
1329 :     return value;
1330 :     }
1331 :    
1332 :     @Override
1333 :     public void forEach(BiConsumer<? super K, ? super V> action) {
1334 :     Node<K,V>[] tab;
1335 :     if (action == null)
1336 :     throw new NullPointerException();
1337 :     if (size > 0 && (tab = table) != null) {
1338 :     int mc = modCount;
1339 :     for (Node<K,V> e : tab) {
1340 :     for (; e != null; e = e.next)
1341 :     action.accept(e.key, e.value);
1342 :     }
1343 :     if (modCount != mc)
1344 :     throw new ConcurrentModificationException();
1345 :     }
1346 :     }
1347 :    
1348 :     @Override
1349 :     public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1350 :     Node<K,V>[] tab;
1351 :     if (function == null)
1352 :     throw new NullPointerException();
1353 :     if (size > 0 && (tab = table) != null) {
1354 :     int mc = modCount;
1355 :     for (Node<K,V> e : tab) {
1356 :     for (; e != null; e = e.next) {
1357 :     e.value = function.apply(e.key, e.value);
1358 :     }
1359 :     }
1360 :     if (modCount != mc)
1361 :     throw new ConcurrentModificationException();
1362 :     }
1363 :     }
1364 :    
1365 :     /* ------------------------------------------------------------ */
1366 :     // Cloning and serialization
1367 :    
1368 :     /**
1369 :     * Returns a shallow copy of this {@code HashMap} instance: the keys and
1370 :     * values themselves are not cloned.
1371 :     *
1372 :     * @return a shallow copy of this map
1373 :     */
1374 :     @SuppressWarnings("unchecked")
1375 :     @Override
1376 :     public Object clone() {
1377 :     HashMap<K,V> result;
1378 :     try {
1379 :     result = (HashMap<K,V>)super.clone();
1380 :     } catch (CloneNotSupportedException e) {
1381 :     // this shouldn't happen, since we are Cloneable
1382 :     throw new InternalError(e);
1383 :     }
1384 :     result.reinitialize();
1385 :     result.putMapEntries(this, false);
1386 :     return result;
1387 :     }
1388 :    
1389 :     // These methods are also used when serializing HashSets
1390 :     final float loadFactor() { return loadFactor; }
1391 :     final int capacity() {
1392 :     return (table != null) ? table.length :
1393 :     (threshold > 0) ? threshold :
1394 :     DEFAULT_INITIAL_CAPACITY;
1395 :     }
1396 :    
1397 :     /**
1398 : jsr166 1.2 * Saves this map to a stream (that is, serializes it).
1399 : jsr166 1.1 *
1400 : jsr166 1.2 * @param s the stream
1401 :     * @throws IOException if an I/O error occurs
1402 : jsr166 1.1 * @serialData The <i>capacity</i> of the HashMap (the length of the
1403 :     * bucket array) is emitted (int), followed by the
1404 :     * <i>size</i> (an int, the number of key-value
1405 :     * mappings), followed by the key (Object) and value (Object)
1406 :     * for each key-value mapping. The key-value mappings are
1407 :     * emitted in no particular order.
1408 :     */
1409 :     private void writeObject(java.io.ObjectOutputStream s)
1410 :     throws IOException {
1411 :     int buckets = capacity();
1412 :     // Write out the threshold, loadfactor, and any hidden stuff
1413 :     s.defaultWriteObject();
1414 :     s.writeInt(buckets);
1415 :     s.writeInt(size);
1416 :     internalWriteEntries(s);
1417 :     }
1418 :    
1419 :     /**
1420 : jsr166 1.2 * Reconstitutes this map from a stream (that is, deserializes it).
1421 :     * @param s the stream
1422 :     * @throws ClassNotFoundException if the class of a serialized object
1423 :     * could not be found
1424 :     * @throws IOException if an I/O error occurs
1425 : jsr166 1.1 */
1426 :     private void readObject(java.io.ObjectInputStream s)
1427 :     throws IOException, ClassNotFoundException {
1428 :     // Read in the threshold (ignored), loadfactor, and any hidden stuff
1429 :     s.defaultReadObject();
1430 :     reinitialize();
1431 :     if (loadFactor <= 0 || Float.isNaN(loadFactor))
1432 :     throw new InvalidObjectException("Illegal load factor: " +
1433 :     loadFactor);
1434 :     s.readInt(); // Read and ignore number of buckets
1435 :     int mappings = s.readInt(); // Read number of mappings (size)
1436 :     if (mappings < 0)
1437 :     throw new InvalidObjectException("Illegal mappings count: " +
1438 :     mappings);
1439 :     else if (mappings > 0) { // (if zero, use defaults)
1440 :     // Size the table using given load factor only if within
1441 :     // range of 0.25...4.0
1442 :     float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1443 :     float fc = (float)mappings / lf + 1.0f;
1444 :     int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1445 :     DEFAULT_INITIAL_CAPACITY :
1446 :     (fc >= MAXIMUM_CAPACITY) ?
1447 :     MAXIMUM_CAPACITY :
1448 :     tableSizeFor((int)fc));
1449 :     float ft = (float)cap * lf;
1450 :     threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1451 :     (int)ft : Integer.MAX_VALUE);
1452 : jsr166 1.3
1453 :     // Check Map.Entry[].class since it's the nearest public type to
1454 :     // what we're actually creating.
1455 :     SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Map.Entry[].class, cap);
1456 : jsr166 1.1 @SuppressWarnings({"rawtypes","unchecked"})
1457 :     Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1458 :     table = tab;
1459 :    
1460 :     // Read the keys and values, and put the mappings in the HashMap
1461 :     for (int i = 0; i < mappings; i++) {
1462 :     @SuppressWarnings("unchecked")
1463 :     K key = (K) s.readObject();
1464 :     @SuppressWarnings("unchecked")
1465 :     V value = (V) s.readObject();
1466 :     putVal(hash(key), key, value, false, false);
1467 :     }
1468 :     }
1469 :     }
1470 :    
1471 :     /* ------------------------------------------------------------ */
1472 :     // iterators
1473 :    
1474 :     abstract class HashIterator {
1475 :     Node<K,V> next; // next entry to return
1476 :     Node<K,V> current; // current entry
1477 :     int expectedModCount; // for fast-fail
1478 :     int index; // current slot
1479 :    
1480 :     HashIterator() {
1481 :     expectedModCount = modCount;
1482 :     Node<K,V>[] t = table;
1483 :     current = next = null;
1484 :     index = 0;
1485 :     if (t != null && size > 0) { // advance to first entry
1486 :     do {} while (index < t.length && (next = t[index++]) == null);
1487 :     }
1488 :     }
1489 :    
1490 :     public final boolean hasNext() {
1491 :     return next != null;
1492 :     }
1493 :    
1494 :     final Node<K,V> nextNode() {
1495 :     Node<K,V>[] t;
1496 :     Node<K,V> e = next;
1497 :     if (modCount != expectedModCount)
1498 :     throw new ConcurrentModificationException();
1499 :     if (e == null)
1500 :     throw new NoSuchElementException();
1501 :     if ((next = (current = e).next) == null && (t = table) != null) {
1502 :     do {} while (index < t.length && (next = t[index++]) == null);
1503 :     }
1504 :     return e;
1505 :     }
1506 :    
1507 :     public final void remove() {
1508 :     Node<K,V> p = current;
1509 :     if (p == null)
1510 :     throw new IllegalStateException();
1511 :     if (modCount != expectedModCount)
1512 :     throw new ConcurrentModificationException();
1513 :     current = null;
1514 :     removeNode(p.hash, p.key, null, false, false);
1515 :     expectedModCount = modCount;
1516 :     }
1517 :     }
1518 :    
1519 :     final class KeyIterator extends HashIterator
1520 :     implements Iterator<K> {
1521 :     public final K next() { return nextNode().key; }
1522 :     }
1523 :    
1524 :     final class ValueIterator extends HashIterator
1525 :     implements Iterator<V> {
1526 :     public final V next() { return nextNode().value; }
1527 :     }
1528 :    
1529 :     final class EntryIterator extends HashIterator
1530 :     implements Iterator<Map.Entry<K,V>> {
1531 :     public final Map.Entry<K,V> next() { return nextNode(); }
1532 :     }
1533 :    
1534 :     /* ------------------------------------------------------------ */
1535 :     // spliterators
1536 :    
1537 :     static class HashMapSpliterator<K,V> {
1538 :     final HashMap<K,V> map;
1539 :     Node<K,V> current; // current node
1540 :     int index; // current index, modified on advance/split
1541 :     int fence; // one past last index
1542 :     int est; // size estimate
1543 :     int expectedModCount; // for comodification checks
1544 :    
1545 :     HashMapSpliterator(HashMap<K,V> m, int origin,
1546 :     int fence, int est,
1547 :     int expectedModCount) {
1548 :     this.map = m;
1549 :     this.index = origin;
1550 :     this.fence = fence;
1551 :     this.est = est;
1552 :     this.expectedModCount = expectedModCount;
1553 :     }
1554 :    
1555 :     final int getFence() { // initialize fence and size on first use
1556 :     int hi;
1557 :     if ((hi = fence) < 0) {
1558 :     HashMap<K,V> m = map;
1559 :     est = m.size;
1560 :     expectedModCount = m.modCount;
1561 :     Node<K,V>[] tab = m.table;
1562 :     hi = fence = (tab == null) ? 0 : tab.length;
1563 :     }
1564 :     return hi;
1565 :     }
1566 :    
1567 :     public final long estimateSize() {
1568 :     getFence(); // force init
1569 :     return (long) est;
1570 :     }
1571 :     }
1572 :    
1573 :     static final class KeySpliterator<K,V>
1574 :     extends HashMapSpliterator<K,V>
1575 :     implements Spliterator<K> {
1576 :     KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1577 :     int expectedModCount) {
1578 :     super(m, origin, fence, est, expectedModCount);
1579 :     }
1580 :    
1581 :     public KeySpliterator<K,V> trySplit() {
1582 :     int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1583 :     return (lo >= mid || current != null) ? null :
1584 :     new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1585 :     expectedModCount);
1586 :     }
1587 :    
1588 :     public void forEachRemaining(Consumer<? super K> action) {
1589 :     int i, hi, mc;
1590 :     if (action == null)
1591 :     throw new NullPointerException();
1592 :     HashMap<K,V> m = map;
1593 :     Node<K,V>[] tab = m.table;
1594 :     if ((hi = fence) < 0) {
1595 :     mc = expectedModCount = m.modCount;
1596 :     hi = fence = (tab == null) ? 0 : tab.length;
1597 :     }
1598 :     else
1599 :     mc = expectedModCount;
1600 :     if (tab != null && tab.length >= hi &&
1601 :     (i = index) >= 0 && (i < (index = hi) || current != null)) {
1602 :     Node<K,V> p = current;
1603 :     current = null;
1604 :     do {
1605 :     if (p == null)
1606 :     p = tab[i++];
1607 :     else {
1608 :     action.accept(p.key);
1609 :     p = p.next;
1610 :     }
1611 :     } while (p != null || i < hi);
1612 :     if (m.modCount != mc)
1613 :     throw new ConcurrentModificationException();
1614 :     }
1615 :     }
1616 :    
1617 :     public boolean tryAdvance(Consumer<? super K> action) {
1618 :     int hi;
1619 :     if (action == null)
1620 :     throw new NullPointerException();
1621 :     Node<K,V>[] tab = map.table;
1622 :     if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1623 :     while (current != null || index < hi) {
1624 :     if (current == null)
1625 :     current = tab[index++];
1626 :     else {
1627 :     K k = current.key;
1628 :     current = current.next;
1629 :     action.accept(k);
1630 :     if (map.modCount != expectedModCount)
1631 :     throw new ConcurrentModificationException();
1632 :     return true;
1633 :     }
1634 :     }
1635 :     }
1636 :     return false;
1637 :     }
1638 :    
1639 :     public int characteristics() {
1640 :     return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1641 :     Spliterator.DISTINCT;
1642 :     }
1643 :     }
1644 :    
1645 :     static final class ValueSpliterator<K,V>
1646 :     extends HashMapSpliterator<K,V>
1647 :     implements Spliterator<V> {
1648 :     ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1649 :     int expectedModCount) {
1650 :     super(m, origin, fence, est, expectedModCount);
1651 :     }
1652 :    
1653 :     public ValueSpliterator<K,V> trySplit() {
1654 :     int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1655 :     return (lo >= mid || current != null) ? null :
1656 :     new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1657 :     expectedModCount);
1658 :     }
1659 :    
1660 :     public void forEachRemaining(Consumer<? super V> action) {
1661 :     int i, hi, mc;
1662 :     if (action == null)
1663 :     throw new NullPointerException();
1664 :     HashMap<K,V> m = map;
1665 :     Node<K,V>[] tab = m.table;
1666 :     if ((hi = fence) < 0) {
1667 :     mc = expectedModCount = m.modCount;
1668 :     hi = fence = (tab == null) ? 0 : tab.length;
1669 :     }
1670 :     else
1671 :     mc = expectedModCount;
1672 :     if (tab != null && tab.length >= hi &&
1673 :     (i = index) >= 0 && (i < (index = hi) || current != null)) {
1674 :     Node<K,V> p = current;
1675 :     current = null;
1676 :     do {
1677 :     if (p == null)
1678 :     p = tab[i++];
1679 :     else {
1680 :     action.accept(p.value);
1681 :     p = p.next;
1682 :     }
1683 :     } while (p != null || i < hi);
1684 :     if (m.modCount != mc)
1685 :     throw new ConcurrentModificationException();
1686 :     }
1687 :     }
1688 :    
1689 :     public boolean tryAdvance(Consumer<? super V> action) {
1690 :     int hi;
1691 :     if (action == null)
1692 :     throw new NullPointerException();
1693 :     Node<K,V>[] tab = map.table;
1694 :     if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1695 :     while (current != null || index < hi) {
1696 :     if (current == null)
1697 :     current = tab[index++];
1698 :     else {
1699 :     V v = current.value;
1700 :     current = current.next;
1701 :     action.accept(v);
1702 :     if (map.modCount != expectedModCount)
1703 :     throw new ConcurrentModificationException();
1704 :     return true;
1705 :     }
1706 :     }
1707 :     }
1708 :     return false;
1709 :     }
1710 :    
1711 :     public int characteristics() {
1712 :     return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1713 :     }
1714 :     }
1715 :    
1716 :     static final class EntrySpliterator<K,V>
1717 :     extends HashMapSpliterator<K,V>
1718 :     implements Spliterator<Map.Entry<K,V>> {
1719 :     EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1720 :     int expectedModCount) {
1721 :     super(m, origin, fence, est, expectedModCount);
1722 :     }
1723 :    
1724 :     public EntrySpliterator<K,V> trySplit() {
1725 :     int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1726 :     return (lo >= mid || current != null) ? null :
1727 :     new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1728 :     expectedModCount);
1729 :     }
1730 :    
1731 :     public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1732 :     int i, hi, mc;
1733 :     if (action == null)
1734 :     throw new NullPointerException();
1735 :     HashMap<K,V> m = map;
1736 :     Node<K,V>[] tab = m.table;
1737 :     if ((hi = fence) < 0) {
1738 :     mc = expectedModCount = m.modCount;
1739 :     hi = fence = (tab == null) ? 0 : tab.length;
1740 :     }
1741 :     else
1742 :     mc = expectedModCount;
1743 :     if (tab != null && tab.length >= hi &&
1744 :     (i = index) >= 0 && (i < (index = hi) || current != null)) {
1745 :     Node<K,V> p = current;
1746 :     current = null;
1747 :     do {
1748 :     if (p == null)
1749 :     p = tab[i++];
1750 :     else {
1751 :     action.accept(p);
1752 :     p = p.next;
1753 :     }
1754 :     } while (p != null || i < hi);
1755 :     if (m.modCount != mc)
1756 :     throw new ConcurrentModificationException();
1757 :     }
1758 :     }
1759 :    
1760 :     public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1761 :     int hi;
1762 :     if (action == null)
1763 :     throw new NullPointerException();
1764 :     Node<K,V>[] tab = map.table;
1765 :     if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1766 :     while (current != null || index < hi) {
1767 :     if (current == null)
1768 :     current = tab[index++];
1769 :     else {
1770 :     Node<K,V> e = current;
1771 :     current = current.next;
1772 :     action.accept(e);
1773 :     if (map.modCount != expectedModCount)
1774 :     throw new ConcurrentModificationException();
1775 :     return true;
1776 :     }
1777 :     }
1778 :     }
1779 :     return false;
1780 :     }
1781 :    
1782 :     public int characteristics() {
1783 :     return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1784 :     Spliterator.DISTINCT;
1785 :     }
1786 :     }
1787 :    
1788 :     /* ------------------------------------------------------------ */
1789 :     // LinkedHashMap support
1790 :    
1791 :    
1792 :     /*
1793 :     * The following package-protected methods are designed to be
1794 :     * overridden by LinkedHashMap, but not by any other subclass.
1795 :     * Nearly all other internal methods are also package-protected
1796 :     * but are declared final, so can be used by LinkedHashMap, view
1797 :     * classes, and HashSet.
1798 :     */
1799 :    
1800 :     // Create a regular (non-tree) node
1801 :     Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1802 :     return new Node<>(hash, key, value, next);
1803 :     }
1804 :    
1805 :     // For conversion from TreeNodes to plain nodes
1806 :     Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1807 :     return new Node<>(p.hash, p.key, p.value, next);
1808 :     }
1809 :    
1810 :     // Create a tree bin node
1811 :     TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1812 :     return new TreeNode<>(hash, key, value, next);
1813 :     }
1814 :    
1815 :     // For treeifyBin
1816 :     TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1817 :     return new TreeNode<>(p.hash, p.key, p.value, next);
1818 :     }
1819 :    
1820 :     /**
1821 :     * Reset to initial default state. Called by clone and readObject.
1822 :     */
1823 :     void reinitialize() {
1824 :     table = null;
1825 :     entrySet = null;
1826 :     keySet = null;
1827 :     values = null;
1828 :     modCount = 0;
1829 :     threshold = 0;
1830 :     size = 0;
1831 :     }
1832 :    
1833 :     // Callbacks to allow LinkedHashMap post-actions
1834 :     void afterNodeAccess(Node<K,V> p) { }
1835 :     void afterNodeInsertion(boolean evict) { }
1836 :     void afterNodeRemoval(Node<K,V> p) { }
1837 :    
1838 :     // Called only from writeObject, to ensure compatible ordering.
1839 :     void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1840 :     Node<K,V>[] tab;
1841 :     if (size > 0 && (tab = table) != null) {
1842 :     for (Node<K,V> e : tab) {
1843 :     for (; e != null; e = e.next) {
1844 :     s.writeObject(e.key);
1845 :     s.writeObject(e.value);
1846 :     }
1847 :     }
1848 :     }
1849 :     }
1850 :    
1851 :     /* ------------------------------------------------------------ */
1852 :     // Tree bins
1853 :    
1854 :     /**
1855 :     * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1856 :     * extends Node) so can be used as extension of either regular or
1857 :     * linked node.
1858 :     */
1859 :     static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1860 :     TreeNode<K,V> parent; // red-black tree links
1861 :     TreeNode<K,V> left;
1862 :     TreeNode<K,V> right;
1863 :     TreeNode<K,V> prev; // needed to unlink next upon deletion
1864 :     boolean red;
1865 :     TreeNode(int hash, K key, V val, Node<K,V> next) {
1866 :     super(hash, key, val, next);
1867 :     }
1868 :    
1869 :     /**
1870 :     * Returns root of tree containing this node.
1871 :     */
1872 :     final TreeNode<K,V> root() {
1873 :     for (TreeNode<K,V> r = this, p;;) {
1874 :     if ((p = r.parent) == null)
1875 :     return r;
1876 :     r = p;
1877 :     }
1878 :     }
1879 :    
1880 :     /**
1881 :     * Ensures that the given root is the first node of its bin.
1882 :     */
1883 :     static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1884 :     int n;
1885 :     if (root != null && tab != null && (n = tab.length) > 0) {
1886 :     int index = (n - 1) & root.hash;
1887 :     TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1888 :     if (root != first) {
1889 :     Node<K,V> rn;
1890 :     tab[index] = root;
1891 :     TreeNode<K,V> rp = root.prev;
1892 :     if ((rn = root.next) != null)
1893 :     ((TreeNode<K,V>)rn).prev = rp;
1894 :     if (rp != null)
1895 :     rp.next = rn;
1896 :     if (first != null)
1897 :     first.prev = root;
1898 :     root.next = first;
1899 :     root.prev = null;
1900 :     }
1901 :     assert checkInvariants(root);
1902 :     }
1903 :     }
1904 :    
1905 :     /**
1906 :     * Finds the node starting at root p with the given hash and key.
1907 :     * The kc argument caches comparableClassFor(key) upon first use
1908 :     * comparing keys.
1909 :     */
1910 :     final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1911 :     TreeNode<K,V> p = this;
1912 :     do {
1913 :     int ph, dir; K pk;
1914 :     TreeNode<K,V> pl = p.left, pr = p.right, q;
1915 :     if ((ph = p.hash) > h)
1916 :     p = pl;
1917 :     else if (ph < h)
1918 :     p = pr;
1919 :     else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1920 :     return p;
1921 :     else if (pl == null)
1922 :     p = pr;
1923 :     else if (pr == null)
1924 :     p = pl;
1925 :     else if ((kc != null ||
1926 :     (kc = comparableClassFor(k)) != null) &&
1927 :     (dir = compareComparables(kc, k, pk)) != 0)
1928 :     p = (dir < 0) ? pl : pr;
1929 :     else if ((q = pr.find(h, k, kc)) != null)
1930 :     return q;
1931 :     else
1932 :     p = pl;
1933 :     } while (p != null);
1934 :     return null;
1935 :     }
1936 :    
1937 :     /**
1938 :     * Calls find for root node.
1939 :     */
1940 :     final TreeNode<K,V> getTreeNode(int h, Object k) {
1941 :     return ((parent != null) ? root() : this).find(h, k, null);
1942 :     }
1943 :    
1944 :     /**
1945 :     * Tie-breaking utility for ordering insertions when equal
1946 :     * hashCodes and non-comparable. We don't require a total
1947 :     * order, just a consistent insertion rule to maintain
1948 :     * equivalence across rebalancings. Tie-breaking further than
1949 :     * necessary simplifies testing a bit.
1950 :     */
1951 :     static int tieBreakOrder(Object a, Object b) {
1952 :     int d;
1953 :     if (a == null || b == null ||
1954 :     (d = a.getClass().getName().
1955 :     compareTo(b.getClass().getName())) == 0)
1956 :     d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1957 :     -1 : 1);
1958 :     return d;
1959 :     }
1960 :    
1961 :     /**
1962 :     * Forms tree of the nodes linked from this node.
1963 :     */
1964 :     final void treeify(Node<K,V>[] tab) {
1965 :     TreeNode<K,V> root = null;
1966 :     for (TreeNode<K,V> x = this, next; x != null; x = next) {
1967 :     next = (TreeNode<K,V>)x.next;
1968 :     x.left = x.right = null;
1969 :     if (root == null) {
1970 :     x.parent = null;
1971 :     x.red = false;
1972 :     root = x;
1973 :     }
1974 :     else {
1975 :     K k = x.key;
1976 :     int h = x.hash;
1977 :     Class<?> kc = null;
1978 :     for (TreeNode<K,V> p = root;;) {
1979 :     int dir, ph;
1980 :     K pk = p.key;
1981 :     if ((ph = p.hash) > h)
1982 :     dir = -1;
1983 :     else if (ph < h)
1984 :     dir = 1;
1985 :     else if ((kc == null &&
1986 :     (kc = comparableClassFor(k)) == null) ||
1987 :     (dir = compareComparables(kc, k, pk)) == 0)
1988 :     dir = tieBreakOrder(k, pk);
1989 :    
1990 :     TreeNode<K,V> xp = p;
1991 :     if ((p = (dir <= 0) ? p.left : p.right) == null) {
1992 :     x.parent = xp;
1993 :     if (dir <= 0)
1994 :     xp.left = x;
1995 :     else
1996 :     xp.right = x;
1997 :     root = balanceInsertion(root, x);
1998 :     break;
1999 :     }
2000 :     }
2001 :     }
2002 :     }
2003 :     moveRootToFront(tab, root);
2004 :     }
2005 :    
2006 :     /**
2007 :     * Returns a list of non-TreeNodes replacing those linked from
2008 :     * this node.
2009 :     */
2010 :     final Node<K,V> untreeify(HashMap<K,V> map) {
2011 :     Node<K,V> hd = null, tl = null;
2012 :     for (Node<K,V> q = this; q != null; q = q.next) {
2013 :     Node<K,V> p = map.replacementNode(q, null);
2014 :     if (tl == null)
2015 :     hd = p;
2016 :     else
2017 :     tl.next = p;
2018 :     tl = p;
2019 :     }
2020 :     return hd;
2021 :     }
2022 :    
2023 :     /**
2024 :     * Tree version of putVal.
2025 :     */
2026 :     final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
2027 :     int h, K k, V v) {
2028 :     Class<?> kc = null;
2029 :     boolean searched = false;
2030 :     TreeNode<K,V> root = (parent != null) ? root() : this;
2031 :     for (TreeNode<K,V> p = root;;) {
2032 :     int dir, ph; K pk;
2033 :     if ((ph = p.hash) > h)
2034 :     dir = -1;
2035 :     else if (ph < h)
2036 :     dir = 1;
2037 :     else if ((pk = p.key) == k || (k != null && k.equals(pk)))
2038 :     return p;
2039 :     else if ((kc == null &&
2040 :     (kc = comparableClassFor(k)) == null) ||
2041 :     (dir = compareComparables(kc, k, pk)) == 0) {
2042 :     if (!searched) {
2043 :     TreeNode<K,V> q, ch;
2044 :     searched = true;
2045 :     if (((ch = p.left) != null &&
2046 :     (q = ch.find(h, k, kc)) != null) ||
2047 :     ((ch = p.right) != null &&
2048 :     (q = ch.find(h, k, kc)) != null))
2049 :     return q;
2050 :     }
2051 :     dir = tieBreakOrder(k, pk);
2052 :     }
2053 :    
2054 :     TreeNode<K,V> xp = p;
2055 :     if ((p = (dir <= 0) ? p.left : p.right) == null) {
2056 :     Node<K,V> xpn = xp.next;
2057 :     TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
2058 :     if (dir <= 0)
2059 :     xp.left = x;
2060 :     else
2061 :     xp.right = x;
2062 :     xp.next = x;
2063 :     x.parent = x.prev = xp;
2064 :     if (xpn != null)
2065 :     ((TreeNode<K,V>)xpn).prev = x;
2066 :     moveRootToFront(tab, balanceInsertion(root, x));
2067 :     return null;
2068 :     }
2069 :     }
2070 :     }
2071 :    
2072 :     /**
2073 :     * Removes the given node, that must be present before this call.
2074 :     * This is messier than typical red-black deletion code because we
2075 :     * cannot swap the contents of an interior node with a leaf
2076 :     * successor that is pinned by "next" pointers that are accessible
2077 :     * independently during traversal. So instead we swap the tree
2078 :     * linkages. If the current tree appears to have too few nodes,
2079 :     * the bin is converted back to a plain bin. (The test triggers
2080 :     * somewhere between 2 and 6 nodes, depending on tree structure).
2081 :     */
2082 :     final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2083 :     boolean movable) {
2084 :     int n;
2085 :     if (tab == null || (n = tab.length) == 0)
2086 :     return;
2087 :     int index = (n - 1) & hash;
2088 :     TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2089 :     TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2090 :     if (pred == null)
2091 :     tab[index] = first = succ;
2092 :     else
2093 :     pred.next = succ;
2094 :     if (succ != null)
2095 :     succ.prev = pred;
2096 :     if (first == null)
2097 :     return;
2098 :     if (root.parent != null)
2099 :     root = root.root();
2100 :     if (root == null
2101 :     || (movable
2102 :     && (root.right == null
2103 :     || (rl = root.left) == null
2104 :     || rl.left == null))) {
2105 :     tab[index] = first.untreeify(map); // too small
2106 :     return;
2107 :     }
2108 :     TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2109 :     if (pl != null && pr != null) {
2110 :     TreeNode<K,V> s = pr, sl;
2111 :     while ((sl = s.left) != null) // find successor
2112 :     s = sl;
2113 :     boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2114 :     TreeNode<K,V> sr = s.right;
2115 :     TreeNode<K,V> pp = p.parent;
2116 :     if (s == pr) { // p was s's direct parent
2117 :     p.parent = s;
2118 :     s.right = p;
2119 :     }
2120 :     else {
2121 :     TreeNode<K,V> sp = s.parent;
2122 :     if ((p.parent = sp) != null) {
2123 :     if (s == sp.left)
2124 :     sp.left = p;
2125 :     else
2126 :     sp.right = p;
2127 :     }
2128 :     if ((s.right = pr) != null)
2129 :     pr.parent = s;
2130 :     }
2131 :     p.left = null;
2132 :     if ((p.right = sr) != null)
2133 :     sr.parent = p;
2134 :     if ((s.left = pl) != null)
2135 :     pl.parent = s;
2136 :     if ((s.parent = pp) == null)
2137 :     root = s;
2138 :     else if (p == pp.left)
2139 :     pp.left = s;
2140 :     else
2141 :     pp.right = s;
2142 :     if (sr != null)
2143 :     replacement = sr;
2144 :     else
2145 :     replacement = p;
2146 :     }
2147 :     else if (pl != null)
2148 :     replacement = pl;
2149 :     else if (pr != null)
2150 :     replacement = pr;
2151 :     else
2152 :     replacement = p;
2153 :     if (replacement != p) {
2154 :     TreeNode<K,V> pp = replacement.parent = p.parent;
2155 :     if (pp == null)
2156 :     root = replacement;
2157 :     else if (p == pp.left)
2158 :     pp.left = replacement;
2159 :     else
2160 :     pp.right = replacement;
2161 :     p.left = p.right = p.parent = null;
2162 :     }
2163 :    
2164 :     TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2165 :    
2166 :     if (replacement == p) { // detach
2167 :     TreeNode<K,V> pp = p.parent;
2168 :     p.parent = null;
2169 :     if (pp != null) {
2170 :     if (p == pp.left)
2171 :     pp.left = null;
2172 :     else if (p == pp.right)
2173 :     pp.right = null;
2174 :     }
2175 :     }
2176 :     if (movable)
2177 :     moveRootToFront(tab, r);
2178 :     }
2179 :    
2180 :     /**
2181 :     * Splits nodes in a tree bin into lower and upper tree bins,
2182 :     * or untreeifies if now too small. Called only from resize;
2183 :     * see above discussion about split bits and indices.
2184 :     *
2185 :     * @param map the map
2186 :     * @param tab the table for recording bin heads
2187 :     * @param index the index of the table being split
2188 :     * @param bit the bit of hash to split on
2189 :     */
2190 :     final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2191 :     TreeNode<K,V> b = this;
2192 :     // Relink into lo and hi lists, preserving order
2193 :     TreeNode<K,V> loHead = null, loTail = null;
2194 :     TreeNode<K,V> hiHead = null, hiTail = null;
2195 :     int lc = 0, hc = 0;
2196 :     for (TreeNode<K,V> e = b, next; e != null; e = next) {
2197 :     next = (TreeNode<K,V>)e.next;
2198 :     e.next = null;
2199 :     if ((e.hash & bit) == 0) {
2200 :     if ((e.prev = loTail) == null)
2201 :     loHead = e;
2202 :     else
2203 :     loTail.next = e;
2204 :     loTail = e;
2205 :     ++lc;
2206 :     }
2207 :     else {
2208 :     if ((e.prev = hiTail) == null)
2209 :     hiHead = e;
2210 :     else
2211 :     hiTail.next = e;
2212 :     hiTail = e;
2213 :     ++hc;
2214 :     }
2215 :     }
2216 :    
2217 :     if (loHead != null) {
2218 :     if (lc <= UNTREEIFY_THRESHOLD)
2219 :     tab[index] = loHead.untreeify(map);
2220 :     else {
2221 :     tab[index] = loHead;
2222 :     if (hiHead != null) // (else is already treeified)
2223 :     loHead.treeify(tab);
2224 :     }
2225 :     }
2226 :     if (hiHead != null) {
2227 :     if (hc <= UNTREEIFY_THRESHOLD)
2228 :     tab[index + bit] = hiHead.untreeify(map);
2229 :     else {
2230 :     tab[index + bit] = hiHead;
2231 :     if (loHead != null)
2232 :     hiHead.treeify(tab);
2233 :     }
2234 :     }
2235 :     }
2236 :    
2237 :     /* ------------------------------------------------------------ */
2238 :     // Red-black tree methods, all adapted from CLR
2239 :    
2240 :     static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2241 :     TreeNode<K,V> p) {
2242 :     TreeNode<K,V> r, pp, rl;
2243 :     if (p != null && (r = p.right) != null) {
2244 :     if ((rl = p.right = r.left) != null)
2245 :     rl.parent = p;
2246 :     if ((pp = r.parent = p.parent) == null)
2247 :     (root = r).red = false;
2248 :     else if (pp.left == p)
2249 :     pp.left = r;
2250 :     else
2251 :     pp.right = r;
2252 :     r.left = p;
2253 :     p.parent = r;
2254 :     }
2255 :     return root;
2256 :     }
2257 :    
2258 :     static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2259 :     TreeNode<K,V> p) {
2260 :     TreeNode<K,V> l, pp, lr;
2261 :     if (p != null && (l = p.left) != null) {
2262 :     if ((lr = p.left = l.right) != null)
2263 :     lr.parent = p;
2264 :     if ((pp = l.parent = p.parent) == null)
2265 :     (root = l).red = false;
2266 :     else if (pp.right == p)
2267 :     pp.right = l;
2268 :     else
2269 :     pp.left = l;
2270 :     l.right = p;
2271 :     p.parent = l;
2272 :     }
2273 :     return root;
2274 :     }
2275 :    
2276 :     static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2277 :     TreeNode<K,V> x) {
2278 :     x.red = true;
2279 :     for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2280 :     if ((xp = x.parent) == null) {
2281 :     x.red = false;
2282 :     return x;
2283 :     }
2284 :     else if (!xp.red || (xpp = xp.parent) == null)
2285 :     return root;
2286 :     if (xp == (xppl = xpp.left)) {
2287 :     if ((xppr = xpp.right) != null && xppr.red) {
2288 :     xppr.red = false;
2289 :     xp.red = false;
2290 :     xpp.red = true;
2291 :     x = xpp;
2292 :     }
2293 :     else {
2294 :     if (x == xp.right) {
2295 :     root = rotateLeft(root, x = xp);
2296 :     xpp = (xp = x.parent) == null ? null : xp.parent;
2297 :     }
2298 :     if (xp != null) {
2299 :     xp.red = false;
2300 :     if (xpp != null) {
2301 :     xpp.red = true;
2302 :     root = rotateRight(root, xpp);
2303 :     }
2304 :     }
2305 :     }
2306 :     }
2307 :     else {
2308 :     if (xppl != null && xppl.red) {
2309 :     xppl.red = false;
2310 :     xp.red = false;
2311 :     xpp.red = true;
2312 :     x = xpp;
2313 :     }
2314 :     else {
2315 :     if (x == xp.left) {
2316 :     root = rotateRight(root, x = xp);
2317 :     xpp = (xp = x.parent) == null ? null : xp.parent;
2318 :     }
2319 :     if (xp != null) {
2320 :     xp.red = false;
2321 :     if (xpp != null) {
2322 :     xpp.red = true;
2323 :     root = rotateLeft(root, xpp);
2324 :     }
2325 :     }
2326 :     }
2327 :     }
2328 :     }
2329 :     }
2330 :    
2331 :     static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2332 :     TreeNode<K,V> x) {
2333 :     for (TreeNode<K,V> xp, xpl, xpr;;) {
2334 :     if (x == null || x == root)
2335 :     return root;
2336 :     else if ((xp = x.parent) == null) {
2337 :     x.red = false;
2338 :     return x;
2339 :     }
2340 :     else if (x.red) {
2341 :     x.red = false;
2342 :     return root;
2343 :     }
2344 :     else if ((xpl = xp.left) == x) {
2345 :     if ((xpr = xp.right) != null && xpr.red) {
2346 :     xpr.red = false;
2347 :     xp.red = true;
2348 :     root = rotateLeft(root, xp);
2349 :     xpr = (xp = x.parent) == null ? null : xp.right;
2350 :     }
2351 :     if (xpr == null)
2352 :     x = xp;
2353 :     else {
2354 :     TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2355 :     if ((sr == null || !sr.red) &&
2356 :     (sl == null || !sl.red)) {
2357 :     xpr.red = true;
2358 :     x = xp;
2359 :     }
2360 :     else {
2361 :     if (sr == null || !sr.red) {
2362 :     if (sl != null)
2363 :     sl.red = false;
2364 :     xpr.red = true;
2365 :     root = rotateRight(root, xpr);
2366 :     xpr = (xp = x.parent) == null ?
2367 :     null : xp.right;
2368 :     }
2369 :     if (xpr != null) {
2370 :     xpr.red = (xp == null) ? false : xp.red;
2371 :     if ((sr = xpr.right) != null)
2372 :     sr.red = false;
2373 :     }
2374 :     if (xp != null) {
2375 :     xp.red = false;
2376 :     root = rotateLeft(root, xp);
2377 :     }
2378 :     x = root;
2379 :     }
2380 :     }
2381 :     }
2382 :     else { // symmetric
2383 :     if (xpl != null && xpl.red) {
2384 :     xpl.red = false;
2385 :     xp.red = true;
2386 :     root = rotateRight(root, xp);
2387 :     xpl = (xp = x.parent) == null ? null : xp.left;
2388 :     }
2389 :     if (xpl == null)
2390 :     x = xp;
2391 :     else {
2392 :     TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2393 :     if ((sl == null || !sl.red) &&
2394 :     (sr == null || !sr.red)) {
2395 :     xpl.red = true;
2396 :     x = xp;
2397 :     }
2398 :     else {
2399 :     if (sl == null || !sl.red) {
2400 :     if (sr != null)
2401 :     sr.red = false;
2402 :     xpl.red = true;
2403 :     root = rotateLeft(root, xpl);
2404 :     xpl = (xp = x.parent) == null ?
2405 :     null : xp.left;
2406 :     }
2407 :     if (xpl != null) {
2408 :     xpl.red = (xp == null) ? false : xp.red;
2409 :     if ((sl = xpl.left) != null)
2410 :     sl.red = false;
2411 :     }
2412 :     if (xp != null) {
2413 :     xp.red = false;
2414 :     root = rotateRight(root, xp);
2415 :     }
2416 :     x = root;
2417 :     }
2418 :     }
2419 :     }
2420 :     }
2421 :     }
2422 :    
2423 :     /**
2424 :     * Recursive invariant check
2425 :     */
2426 :     static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2427 :     TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2428 :     tb = t.prev, tn = (TreeNode<K,V>)t.next;
2429 :     if (tb != null && tb.next != t)
2430 :     return false;
2431 :     if (tn != null && tn.prev != t)
2432 :     return false;
2433 :     if (tp != null && t != tp.left && t != tp.right)
2434 :     return false;
2435 :     if (tl != null && (tl.parent != t || tl.hash > t.hash))
2436 :     return false;
2437 :     if (tr != null && (tr.parent != t || tr.hash < t.hash))
2438 :     return false;
2439 :     if (t.red && tl != null && tl.red && tr != null && tr.red)
2440 :     return false;
2441 :     if (tl != null && !checkInvariants(tl))
2442 :     return false;
2443 :     if (tr != null && !checkInvariants(tr))
2444 :     return false;
2445 :     return true;
2446 :     }
2447 :     }
2448 :    
2449 :     }

Doug Lea
ViewVC Help
Powered by ViewVC 1.0.8