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

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