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
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
38 /**
39 * Hash table based implementation of the <tt>Map</tt> interface. This
40 * implementation provides all of the optional map operations, and permits
41 * <tt>null</tt> values and the <tt>null</tt> key. (The <tt>HashMap</tt>
42 * class is roughly equivalent to <tt>Hashtable</tt>, 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 (<tt>get</tt> and <tt>put</tt>), 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 * <tt>HashMap</tt> 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 <tt>HashMap</tt> 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 <tt>HashMap</tt> class, including
71 * <tt>get</tt> and <tt>put</tt>). 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 <tt>HashMap</tt>
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 * <tt>remove</tt> 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 <tt>ConcurrentModificationException</tt> 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}/../technotes/guides/collections/index.html">
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 'cached' if != null, else
343 * returns x's Class if it is of the form "class C implements
344 * Comparable<C>", else void.class.
345 */
346 static Class<?> comparableClassFor(Class<?> cached, Object x) {
347 if (cached != null) {
348 return cached;
349 }
350 if (x instanceof Comparable) {
351 Class<?> c; Type[] ts, as; ParameterizedType p;
352 if ((c = x.getClass()) == String.class) // bypass checks
353 return c;
354 if ((ts = c.getGenericInterfaces()) != null) {
355 for (Type t : ts) {
356 if ((t instanceof ParameterizedType) &&
357 ((p = (ParameterizedType) t).getRawType() ==
358 Comparable.class) &&
359 (as = p.getActualTypeArguments()) != null &&
360 as.length == 1 && as[0] == c) // type arg is c
361 return c;
362 }
363 }
364 }
365 return void.class;
366 }
367
368 /**
369 * Returns k.compareTo(x) if x matches kc (k's screened comparable
370 * class), else 0.
371 */
372 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
373 static int compareComparables(Class<?> kc, Object k, Object x) {
374 return (x == null || x.getClass() != kc ? 0 :
375 ((Comparable)k).compareTo(x));
376 }
377
378 /**
379 * Returns a power of two size for the given target capacity.
380 */
381 static final int tableSizeFor(int cap) {
382 int n = cap - 1;
383 n |= n >>> 1;
384 n |= n >>> 2;
385 n |= n >>> 4;
386 n |= n >>> 8;
387 n |= n >>> 16;
388 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
389 }
390
391 /* ---------------- Fields -------------- */
392
393 /**
394 * The table, initialized on first use, and resized as
395 * necessary. When allocated, length is always a power of two.
396 * (We also tolerate length zero in some operations to allow
397 * bootstrapping mechanics that are currently not needed.)
398 */
399 transient Node<K,V>[] table;
400
401 /**
402 * Holds cached entrySet(). Note that AbstractMap fields are used
403 * for keySet() and values().
404 */
405 transient Set<Map.Entry<K,V>> entrySet;
406
407 /**
408 * The number of key-value mappings contained in this map.
409 */
410 transient int size;
411
412 /**
413 * The number of times this HashMap has been structurally modified
414 * Structural modifications are those that change the number of mappings in
415 * the HashMap or otherwise modify its internal structure (e.g.,
416 * rehash). This field is used to make iterators on Collection-views of
417 * the HashMap fail-fast. (See ConcurrentModificationException).
418 */
419 transient int modCount;
420
421 /**
422 * The next size value at which to resize (capacity * load factor).
423 *
424 * @serial
425 */
426 // (The javadoc description is true upon serialization.
427 // Additionally, if the table array has not been allocated, this
428 // field holds the initial array capacity, or zero signifying
429 // DEFAULT_INITIAL_CAPACITY.)
430 int threshold;
431
432 /**
433 * The load factor for the hash table.
434 *
435 * @serial
436 */
437 final float loadFactor;
438
439 /* ---------------- Public operations -------------- */
440
441 /**
442 * Constructs an empty <tt>HashMap</tt> with the specified initial
443 * capacity and load factor.
444 *
445 * @param initialCapacity the initial capacity
446 * @param loadFactor the load factor
447 * @throws IllegalArgumentException if the initial capacity is negative
448 * or the load factor is nonpositive
449 */
450 public HashMap(int initialCapacity, float loadFactor) {
451 if (initialCapacity < 0)
452 throw new IllegalArgumentException("Illegal initial capacity: " +
453 initialCapacity);
454 if (initialCapacity > MAXIMUM_CAPACITY)
455 initialCapacity = MAXIMUM_CAPACITY;
456 if (loadFactor <= 0 || Float.isNaN(loadFactor))
457 throw new IllegalArgumentException("Illegal load factor: " +
458 loadFactor);
459 this.loadFactor = loadFactor;
460 this.threshold = tableSizeFor(initialCapacity);
461 }
462
463 /**
464 * Constructs an empty <tt>HashMap</tt> with the specified initial
465 * capacity and the default load factor (0.75).
466 *
467 * @param initialCapacity the initial capacity.
468 * @throws IllegalArgumentException if the initial capacity is negative.
469 */
470 public HashMap(int initialCapacity) {
471 this(initialCapacity, DEFAULT_LOAD_FACTOR);
472 }
473
474 /**
475 * Constructs an empty <tt>HashMap</tt> with the default initial capacity
476 * (16) and the default load factor (0.75).
477 */
478 public HashMap() {
479 this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
480 }
481
482 /**
483 * Constructs a new <tt>HashMap</tt> with the same mappings as the
484 * specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
485 * default load factor (0.75) and an initial capacity sufficient to
486 * hold the mappings in the specified <tt>Map</tt>.
487 *
488 * @param m the map whose mappings are to be placed in this map
489 * @throws NullPointerException if the specified map is null
490 */
491 public HashMap(Map<? extends K, ? extends V> m) {
492 this.loadFactor = DEFAULT_LOAD_FACTOR;
493 putMapEntries(m, false);
494 }
495
496 /**
497 * Implements Map.putAll and Map constructor
498 *
499 * @param m the map
500 * @param evict false when initially constructing this map, else
501 * true (relayed to method afterNodeInsertion).
502 */
503 final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
504 int s = m.size();
505 if (s > 0) {
506 if (table == null) { // pre-size
507 float ft = ((float)s / loadFactor) + 1.0F;
508 int t = ((ft < (float)MAXIMUM_CAPACITY) ?
509 (int)ft : MAXIMUM_CAPACITY);
510 if (t > threshold)
511 threshold = tableSizeFor(t);
512 }
513 else if (s > threshold)
514 resize();
515 for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
516 K key = e.getKey();
517 V value = e.getValue();
518 putVal(hash(key), key, value, false, evict);
519 }
520 }
521 }
522
523 /**
524 * Returns the number of key-value mappings in this map.
525 *
526 * @return the number of key-value mappings in this map
527 */
528 public int size() {
529 return size;
530 }
531
532 /**
533 * Returns <tt>true</tt> if this map contains no key-value mappings.
534 *
535 * @return <tt>true</tt> if this map contains no key-value mappings
536 */
537 public boolean isEmpty() {
538 return size == 0;
539 }
540
541 /**
542 * Returns the value to which the specified key is mapped,
543 * or {@code null} if this map contains no mapping for the key.
544 *
545 * <p>More formally, if this map contains a mapping from a key
546 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
547 * key.equals(k))}, then this method returns {@code v}; otherwise
548 * it returns {@code null}. (There can be at most one such mapping.)
549 *
550 * <p>A return value of {@code null} does not <i>necessarily</i>
551 * indicate that the map contains no mapping for the key; it's also
552 * possible that the map explicitly maps the key to {@code null}.
553 * The {@link #containsKey containsKey} operation may be used to
554 * distinguish these two cases.
555 *
556 * @see #put(Object, Object)
557 */
558 public V get(Object key) {
559 Node<K,V> e;
560 return (e = getNode(hash(key), key)) == null ? null : e.value;
561 }
562
563 /**
564 * Implements Map.get and related methods
565 *
566 * @param hash hash for key
567 * @param key the key
568 * @return the node, or null if none
569 */
570 final Node<K,V> getNode(int hash, Object key) {
571 Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
572 if ((tab = table) != null && (n = tab.length) > 0 &&
573 (first = tab[(n - 1) & hash]) != null) {
574 if (first.hash == hash && // always check first node
575 ((k = first.key) == key || (key != null && key.equals(k))))
576 return first;
577 if ((e = first.next) != null) {
578 if (first instanceof TreeNode)
579 return ((TreeNode<K,V>)first).getTreeNode(hash, key);
580 do {
581 if (e.hash == hash &&
582 ((k = e.key) == key || (key != null && key.equals(k))))
583 return e;
584 } while ((e = e.next) != null);
585 }
586 }
587 return null;
588 }
589
590 /**
591 * Returns <tt>true</tt> if this map contains a mapping for the
592 * specified key.
593 *
594 * @param key The key whose presence in this map is to be tested
595 * @return <tt>true</tt> if this map contains a mapping for the specified
596 * key.
597 */
598 public boolean containsKey(Object key) {
599 return getNode(hash(key), key) != null;
600 }
601
602 /**
603 * Associates the specified value with the specified key in this map.
604 * If the map previously contained a mapping for the key, the old
605 * value is replaced.
606 *
607 * @param key key with which the specified value is to be associated
608 * @param value value to be associated with the specified key
609 * @return the previous value associated with <tt>key</tt>, or
610 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
611 * (A <tt>null</tt> return can also indicate that the map
612 * previously associated <tt>null</tt> with <tt>key</tt>.)
613 */
614 public V put(K key, V value) {
615 return putVal(hash(key), key, value, false, true);
616 }
617
618 /**
619 * Implements Map.put and related methods
620 *
621 * @param hash hash for key
622 * @param key the key
623 * @param value the value to put
624 * @param onlyIfAbsent if true, don't change existing value
625 * @param evict if false, the table is in creation mode.
626 * @return previous value, or null if none
627 */
628 final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
629 boolean evict) {
630 Node<K,V>[] tab; Node<K,V> p; int n, i;
631 if ((tab = table) == null || (n = tab.length) == 0)
632 n = (tab = resize()).length;
633 if ((p = tab[i = (n - 1) & hash]) == null)
634 tab[i] = newNode(hash, key, value, null);
635 else {
636 Node<K,V> e; K k;
637 if (p.hash == hash &&
638 ((k = p.key) == key || (key != null && key.equals(k))))
639 e = p;
640 else if (p instanceof TreeNode)
641 e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
642 else {
643 for (int binCount = 0; ; ++binCount) {
644 if ((e = p.next) == null) {
645 p.next = newNode(hash, key, value, null);
646 if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
647 treeifyBin(tab, hash);
648 break;
649 }
650 if (e.hash == hash &&
651 ((k = e.key) == key || (key != null && key.equals(k))))
652 break;
653 p = e;
654 }
655 }
656 if (e != null) { // existing mapping for key
657 V oldValue = e.value;
658 if (!onlyIfAbsent || oldValue == null)
659 e.value = value;
660 afterNodeAccess(e);
661 return oldValue;
662 }
663 }
664 ++modCount;
665 if (++size > threshold)
666 resize();
667 afterNodeInsertion(evict);
668 return null;
669 }
670
671 /**
672 * Initializes or doubles table size. If null, allocates in
673 * accord with initial capacity target held in field threshold.
674 * Otherwise, because we are using power-of-two expansion, the
675 * elements from each bin must either stay at same index, or move
676 * with a power of two offset in the new table.
677 *
678 * @return the table
679 */
680 final Node<K,V>[] resize() {
681 Node<K,V>[] oldTab = table;
682 int oldCap = (oldTab == null) ? 0 : oldTab.length;
683 int oldThr = threshold;
684 int newCap, newThr = 0;
685 if (oldCap > 0) {
686 if (oldCap >= MAXIMUM_CAPACITY) {
687 threshold = Integer.MAX_VALUE;
688 return oldTab;
689 }
690 else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
691 oldCap >= DEFAULT_INITIAL_CAPACITY)
692 newThr = oldThr << 1; // double threshold
693 }
694 else if (oldThr > 0) // initial capacity was placed in threshold
695 newCap = oldThr;
696 else { // zero initial threshold signifies using defaults
697 newCap = DEFAULT_INITIAL_CAPACITY;
698 newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
699 }
700 if (newThr == 0) {
701 float ft = (float)newCap * loadFactor;
702 newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
703 (int)ft : Integer.MAX_VALUE);
704 }
705 threshold = newThr;
706 @SuppressWarnings({"rawtypes","unchecked"})
707 Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
708 table = newTab;
709 if (oldTab != null) {
710 for (int j = 0; j < oldCap; ++j) {
711 Node<K,V> e;
712 if ((e = oldTab[j]) != null) {
713 oldTab[j] = null;
714 if (e.next == null)
715 newTab[e.hash & (newCap - 1)] = e;
716 else if (e instanceof TreeNode)
717 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
718 else { // preserve order
719 Node<K,V> loHead = null, loTail = null;
720 Node<K,V> hiHead = null, hiTail = null;
721 Node<K,V> next;
722 do {
723 next = e.next;
724 if ((e.hash & oldCap) == 0) {
725 if (loTail == null)
726 loHead = e;
727 else
728 loTail.next = e;
729 loTail = e;
730 }
731 else {
732 if (hiTail == null)
733 hiHead = e;
734 else
735 hiTail.next = e;
736 hiTail = e;
737 }
738 } while ((e = next) != null);
739 if (loTail != null) {
740 loTail.next = null;
741 newTab[j] = loHead;
742 }
743 if (hiTail != null) {
744 hiTail.next = null;
745 newTab[j + oldCap] = hiHead;
746 }
747 }
748 }
749 }
750 }
751 return newTab;
752 }
753
754 /**
755 * Replaces all linked nodes in bin at index for given hash unless
756 * table is too small, in which case resizes instead.
757 */
758 final void treeifyBin(Node<K,V>[] tab, int hash) {
759 int n, index; Node<K,V> e;
760 if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
761 resize();
762 else if ((e = tab[index = (n - 1) & hash]) != null) {
763 TreeNode<K,V> hd = null, tl = null;
764 do {
765 TreeNode<K,V> p = replacementTreeNode(e, null);
766 if (tl == null)
767 hd = p;
768 else {
769 p.prev = tl;
770 tl.next = p;
771 }
772 tl = p;
773 } while ((e = e.next) != null);
774 if ((tab[index] = hd) != null)
775 hd.treeify(tab);
776 }
777 }
778
779 /**
780 * Copies all of the mappings from the specified map to this map.
781 * These mappings will replace any mappings that this map had for
782 * any of the keys currently in the specified map.
783 *
784 * @param m mappings to be stored in this map
785 * @throws NullPointerException if the specified map is null
786 */
787 public void putAll(Map<? extends K, ? extends V> m) {
788 putMapEntries(m, true);
789 }
790
791 /**
792 * Removes the mapping for the specified key from this map if present.
793 *
794 * @param key key whose mapping is to be removed from the map
795 * @return the previous value associated with <tt>key</tt>, or
796 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
797 * (A <tt>null</tt> return can also indicate that the map
798 * previously associated <tt>null</tt> with <tt>key</tt>.)
799 */
800 public V remove(Object key) {
801 Node<K,V> e;
802 return (e = removeNode(hash(key), key, null, false, true)) == null ?
803 null : e.value;
804 }
805
806 /**
807 * Implements Map.remove and related methods
808 *
809 * @param hash hash for key
810 * @param key the key
811 * @param value the value to match if matchValue, else ignored
812 * @param matchValue if true only remove if value is equal
813 * @param movable if false do not move other nodes while removing
814 * @return the node, or null if none
815 */
816 final Node<K,V> removeNode(int hash, Object key, Object value,
817 boolean matchValue, boolean movable) {
818 Node<K,V>[] tab; Node<K,V> p; int n, index;
819 if ((tab = table) != null && (n = tab.length) > 0 &&
820 (p = tab[index = (n - 1) & hash]) != null) {
821 Node<K,V> node = null, e; K k; V v;
822 if (p.hash == hash &&
823 ((k = p.key) == key || (key != null && key.equals(k))))
824 node = p;
825 else if ((e = p.next) != null) {
826 if (p instanceof TreeNode)
827 node = ((TreeNode<K,V>)p).getTreeNode(hash, key);
828 else {
829 do {
830 if (e.hash == hash &&
831 ((k = e.key) == key ||
832 (key != null && key.equals(k)))) {
833 node = e;
834 break;
835 }
836 p = e;
837 } while ((e = e.next) != null);
838 }
839 }
840 if (node != null && (!matchValue || (v = node.value) == value ||
841 (value != null && value.equals(v)))) {
842 if (node instanceof TreeNode)
843 ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable);
844 else if (node == p)
845 tab[index] = node.next;
846 else
847 p.next = node.next;
848 ++modCount;
849 --size;
850 afterNodeRemoval(node);
851 return node;
852 }
853 }
854 return null;
855 }
856
857 /**
858 * Removes all of the mappings from this map.
859 * The map will be empty after this call returns.
860 */
861 public void clear() {
862 Node<K,V>[] tab;
863 modCount++;
864 if ((tab = table) != null && size > 0) {
865 size = 0;
866 for (int i = 0; i < tab.length; ++i)
867 tab[i] = null;
868 }
869 }
870
871 /**
872 * Returns <tt>true</tt> if this map maps one or more keys to the
873 * specified value.
874 *
875 * @param value value whose presence in this map is to be tested
876 * @return <tt>true</tt> if this map maps one or more keys to the
877 * specified value
878 */
879 public boolean containsValue(Object value) {
880 Node<K,V>[] tab; V v;
881 if ((tab = table) != null && size > 0) {
882 for (Node<K, V> e : tab) {
883 for (; e != null; e = e.next) {
884 if ((v = e.value) == value ||
885 (value != null && value.equals(v)))
886 return true;
887 }
888 }
889 }
890 return false;
891 }
892
893 /**
894 * Returns a {@link Set} view of the keys contained in this map.
895 * The set is backed by the map, so changes to the map are
896 * reflected in the set, and vice-versa. If the map is modified
897 * while an iteration over the set is in progress (except through
898 * the iterator's own <tt>remove</tt> operation), the results of
899 * the iteration are undefined. The set supports element removal,
900 * which removes the corresponding mapping from the map, via the
901 * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
902 * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
903 * operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
904 * operations.
905 *
906 * @return a set view of the keys contained in this map
907 */
908 public Set<K> keySet() {
909 Set<K> ks;
910 return (ks = keySet) == null ? (keySet = new KeySet()) : 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 <tt>remove</tt> 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 <tt>Iterator.remove</tt>,
949 * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
950 * <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
951 * support the <tt>add</tt> or <tt>addAll</tt> operations.
952 *
953 * @return a view of the values contained in this map
954 */
955 public Collection<V> values() {
956 Collection<V> vs;
957 return (vs = values) == null ? (values = new Values()) : vs;
958 }
959
960 final class Values extends AbstractCollection<V> {
961 public final int size() { return size; }
962 public final void clear() { HashMap.this.clear(); }
963 public final Iterator<V> iterator() { return new ValueIterator(); }
964 public final boolean contains(Object o) { return containsValue(o); }
965 public final Spliterator<V> spliterator() {
966 return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
967 }
968 public final void forEach(Consumer<? super V> action) {
969 Node<K,V>[] tab;
970 if (action == null)
971 throw new NullPointerException();
972 if (size > 0 && (tab = table) != null) {
973 int mc = modCount;
974 for (Node<K, V> e : tab) {
975 for (; e != null; e = e.next)
976 action.accept(e.value);
977 }
978 if (modCount != mc)
979 throw new ConcurrentModificationException();
980 }
981 }
982 }
983
984 /**
985 * Returns a {@link Set} view of the mappings contained in this map.
986 * The set is backed by the map, so changes to the map are
987 * reflected in the set, and vice-versa. If the map is modified
988 * while an iteration over the set is in progress (except through
989 * the iterator's own <tt>remove</tt> operation, or through the
990 * <tt>setValue</tt> operation on a map entry returned by the
991 * iterator) the results of the iteration are undefined. The set
992 * supports element removal, which removes the corresponding
993 * mapping from the map, via the <tt>Iterator.remove</tt>,
994 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
995 * <tt>clear</tt> operations. It does not support the
996 * <tt>add</tt> or <tt>addAll</tt> operations.
997 *
998 * @return a set view of the mappings contained in this map
999 */
1000 public Set<Map.Entry<K,V>> entrySet() {
1001 Set<Map.Entry<K,V>> es;
1002 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
1003 }
1004
1005 final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1006 public final int size() { return size; }
1007 public final void clear() { HashMap.this.clear(); }
1008 public final Iterator<Map.Entry<K,V>> iterator() {
1009 return new EntryIterator();
1010 }
1011 public final boolean contains(Object o) {
1012 if (!(o instanceof Map.Entry))
1013 return false;
1014 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1015 Object key = e.getKey();
1016 Node<K,V> candidate = getNode(hash(key), key);
1017 return candidate != null && candidate.equals(e);
1018 }
1019 public final boolean remove(Object o) {
1020 if (o instanceof Map.Entry) {
1021 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1022 Object key = e.getKey();
1023 Object value = e.getValue();
1024 return removeNode(hash(key), key, value, true, true) != null;
1025 }
1026 return false;
1027 }
1028 public final Spliterator<Map.Entry<K,V>> spliterator() {
1029 return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
1030 }
1031 public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1032 Node<K,V>[] tab;
1033 if (action == null)
1034 throw new NullPointerException();
1035 if (size > 0 && (tab = table) != null) {
1036 int mc = modCount;
1037 for (Node<K, V> e : tab) {
1038 for (; e != null; e = e.next)
1039 action.accept(e);
1040 }
1041 if (modCount != mc)
1042 throw new ConcurrentModificationException();
1043 }
1044 }
1045 }
1046
1047 // Overrides of JDK8 Map extension methods
1048
1049 @Override
1050 public V getOrDefault(Object key, V defaultValue) {
1051 Node<K,V> e;
1052 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1053 }
1054
1055 @Override
1056 public V putIfAbsent(K key, V value) {
1057 return putVal(hash(key), key, value, true, true);
1058 }
1059
1060 @Override
1061 public boolean remove(Object key, Object value) {
1062 return removeNode(hash(key), key, value, true, true) != null;
1063 }
1064
1065 @Override
1066 public boolean replace(K key, V oldValue, V newValue) {
1067 Node<K,V> e; V v;
1068 if ((e = getNode(hash(key), key)) != null &&
1069 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1070 e.value = newValue;
1071 afterNodeAccess(e);
1072 return true;
1073 }
1074 return false;
1075 }
1076
1077 @Override
1078 public V replace(K key, V value) {
1079 Node<K,V> e;
1080 if ((e = getNode(hash(key), key)) != null) {
1081 V oldValue = e.value;
1082 e.value = value;
1083 afterNodeAccess(e);
1084 return oldValue;
1085 }
1086 return null;
1087 }
1088
1089 @Override
1090 public V computeIfAbsent(K key,
1091 Function<? super K, ? extends V> mappingFunction) {
1092 if (mappingFunction == null)
1093 throw new NullPointerException();
1094 int hash = hash(key);
1095 Node<K,V>[] tab; Node<K,V> first; int n, i;
1096 int binCount = 0;
1097 TreeNode<K,V> t = null;
1098 Node<K,V> old = null;
1099 if (size > threshold || (tab = table) == null ||
1100 (n = tab.length) == 0)
1101 n = (tab = resize()).length;
1102 if ((first = tab[i = (n - 1) & hash]) != null) {
1103 if (first instanceof TreeNode)
1104 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1105 else {
1106 Node<K,V> e = first; K k;
1107 do {
1108 if (e.hash == hash &&
1109 ((k = e.key) == key || (key != null && key.equals(k)))) {
1110 old = e;
1111 break;
1112 }
1113 ++binCount;
1114 } while ((e = e.next) != null);
1115 }
1116 V oldValue;
1117 if (old != null && (oldValue = old.value) != null) {
1118 afterNodeAccess(old);
1119 return oldValue;
1120 }
1121 }
1122 V v = mappingFunction.apply(key);
1123 if (v == null) {
1124 return null;
1125 } else if (old != null) {
1126 old.value = v;
1127 afterNodeAccess(old);
1128 return v;
1129 }
1130 else if (t != null)
1131 t.putTreeVal(this, tab, hash, key, v);
1132 else {
1133 tab[i] = newNode(hash, key, v, first);
1134 if (binCount >= TREEIFY_THRESHOLD - 1)
1135 treeifyBin(tab, hash);
1136 }
1137 ++modCount;
1138 ++size;
1139 afterNodeInsertion(true);
1140 return v;
1141 }
1142
1143 public V computeIfPresent(K key,
1144 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1145 if (remappingFunction == null)
1146 throw new NullPointerException();
1147 Node<K,V> e; V oldValue;
1148 int hash = hash(key);
1149 if ((e = getNode(hash, key)) != null &&
1150 (oldValue = e.value) != null) {
1151 V v = remappingFunction.apply(key, oldValue);
1152 if (v != null) {
1153 e.value = v;
1154 afterNodeAccess(e);
1155 return v;
1156 }
1157 else
1158 removeNode(hash, key, null, false, true);
1159 }
1160 return null;
1161 }
1162
1163 @Override
1164 public V compute(K key,
1165 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1166 if (remappingFunction == null)
1167 throw new NullPointerException();
1168 int hash = hash(key);
1169 Node<K,V>[] tab; Node<K,V> first; int n, i;
1170 int binCount = 0;
1171 TreeNode<K,V> t = null;
1172 Node<K,V> old = null;
1173 if (size > threshold || (tab = table) == null ||
1174 (n = tab.length) == 0)
1175 n = (tab = resize()).length;
1176 if ((first = tab[i = (n - 1) & hash]) != null) {
1177 if (first instanceof TreeNode)
1178 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1179 else {
1180 Node<K,V> e = first; K k;
1181 do {
1182 if (e.hash == hash &&
1183 ((k = e.key) == key || (key != null && key.equals(k)))) {
1184 old = e;
1185 break;
1186 }
1187 ++binCount;
1188 } while ((e = e.next) != null);
1189 }
1190 }
1191 V oldValue = (old == null) ? null : old.value;
1192 V v = remappingFunction.apply(key, oldValue);
1193 if (old != null) {
1194 if (v != null) {
1195 old.value = v;
1196 afterNodeAccess(old);
1197 }
1198 else
1199 removeNode(hash, key, null, false, true);
1200 }
1201 else if (v != null) {
1202 if (t != null)
1203 t.putTreeVal(this, tab, hash, key, v);
1204 else {
1205 tab[i] = newNode(hash, key, v, first);
1206 if (binCount >= TREEIFY_THRESHOLD - 1)
1207 treeifyBin(tab, hash);
1208 }
1209 ++modCount;
1210 ++size;
1211 afterNodeInsertion(true);
1212 }
1213 return v;
1214 }
1215
1216 @Override
1217 public V merge(K key, V value,
1218 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1219 if (value == null)
1220 throw new NullPointerException();
1221 if (remappingFunction == null)
1222 throw new NullPointerException();
1223 int hash = hash(key);
1224 Node<K,V>[] tab; Node<K,V> first; int n, i;
1225 int binCount = 0;
1226 TreeNode<K,V> t = null;
1227 Node<K,V> old = null;
1228 if (size > threshold || (tab = table) == null ||
1229 (n = tab.length) == 0)
1230 n = (tab = resize()).length;
1231 if ((first = tab[i = (n - 1) & hash]) != null) {
1232 if (first instanceof TreeNode)
1233 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1234 else {
1235 Node<K,V> e = first; K k;
1236 do {
1237 if (e.hash == hash &&
1238 ((k = e.key) == key || (key != null && key.equals(k)))) {
1239 old = e;
1240 break;
1241 }
1242 ++binCount;
1243 } while ((e = e.next) != null);
1244 }
1245 }
1246 if (old != null) {
1247 V v;
1248 if (old.value != null)
1249 v = remappingFunction.apply(old.value, value);
1250 else
1251 v = value;
1252 if (v != null) {
1253 old.value = v;
1254 afterNodeAccess(old);
1255 }
1256 else
1257 removeNode(hash, key, null, false, true);
1258 return v;
1259 }
1260 if (value != null) {
1261 if (t != null)
1262 t.putTreeVal(this, tab, hash, key, value);
1263 else {
1264 tab[i] = newNode(hash, key, value, first);
1265 if (binCount >= TREEIFY_THRESHOLD - 1)
1266 treeifyBin(tab, hash);
1267 }
1268 ++modCount;
1269 ++size;
1270 afterNodeInsertion(true);
1271 }
1272 return value;
1273 }
1274
1275 @Override
1276 public void forEach(BiConsumer<? super K, ? super V> action) {
1277 Node<K,V>[] tab;
1278 if (action == null)
1279 throw new NullPointerException();
1280 if (size > 0 && (tab = table) != null) {
1281 int mc = modCount;
1282 for (Node<K, V> e : tab) {
1283 for (; e != null; e = e.next)
1284 action.accept(e.key, e.value);
1285 }
1286 if (modCount != mc)
1287 throw new ConcurrentModificationException();
1288 }
1289 }
1290
1291 @Override
1292 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1293 Node<K,V>[] tab;
1294 if (function == null)
1295 throw new NullPointerException();
1296 if (size > 0 && (tab = table) != null) {
1297 int mc = modCount;
1298 for (Node<K, V> e : tab) {
1299 for (; e != null; e = e.next) {
1300 e.value = function.apply(e.key, e.value);
1301 }
1302 }
1303 if (modCount != mc)
1304 throw new ConcurrentModificationException();
1305 }
1306 }
1307
1308 /* ------------------------------------------------------------ */
1309 // Cloning and serialization
1310
1311 /**
1312 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
1313 * values themselves are not cloned.
1314 *
1315 * @return a shallow copy of this map
1316 */
1317 @SuppressWarnings("unchecked")
1318 @Override
1319 public Object clone() {
1320 HashMap<K,V> result;
1321 try {
1322 result = (HashMap<K,V>)super.clone();
1323 } catch (CloneNotSupportedException e) {
1324 // this shouldn't happen, since we are Cloneable
1325 throw new InternalError(e);
1326 }
1327 result.reinitialize();
1328 result.putMapEntries(this, false);
1329 return result;
1330 }
1331
1332 // These methods are also used when serializing HashSets
1333 final float loadFactor() { return loadFactor; }
1334 final int capacity() {
1335 return (table != null) ? table.length :
1336 (threshold > 0) ? threshold :
1337 DEFAULT_INITIAL_CAPACITY;
1338 }
1339
1340 /**
1341 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
1342 * serialize it).
1343 *
1344 * @serialData The <i>capacity</i> of the HashMap (the length of the
1345 * bucket array) is emitted (int), followed by the
1346 * <i>size</i> (an int, the number of key-value
1347 * mappings), followed by the key (Object) and value (Object)
1348 * for each key-value mapping. The key-value mappings are
1349 * emitted in no particular order.
1350 */
1351 private void writeObject(java.io.ObjectOutputStream s)
1352 throws IOException {
1353 int buckets = capacity();
1354 // Write out the threshold, loadfactor, and any hidden stuff
1355 s.defaultWriteObject();
1356 s.writeInt(buckets);
1357 s.writeInt(size);
1358 internalWriteEntries(s);
1359 }
1360
1361 /**
1362 * Reconstitute the {@code HashMap} instance from a stream (i.e.,
1363 * deserialize it).
1364 */
1365 private void readObject(java.io.ObjectInputStream s)
1366 throws IOException, ClassNotFoundException {
1367 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1368 s.defaultReadObject();
1369 reinitialize();
1370 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1371 throw new InvalidObjectException("Illegal load factor: " +
1372 loadFactor);
1373 s.readInt(); // Read and ignore number of buckets
1374 int mappings = s.readInt(); // Read number of mappings (size)
1375 if (mappings < 0)
1376 throw new InvalidObjectException("Illegal mappings count: " +
1377 mappings);
1378 else if (mappings > 0) { // (if zero, use defaults)
1379 // Size the table using given load factor only if within
1380 // range of 0.25...4.0
1381 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1382 float fc = (float)mappings / lf + 1.0f;
1383 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1384 DEFAULT_INITIAL_CAPACITY :
1385 (fc >= MAXIMUM_CAPACITY) ?
1386 MAXIMUM_CAPACITY :
1387 tableSizeFor((int)fc));
1388 float ft = (float)cap * lf;
1389 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1390 (int)ft : Integer.MAX_VALUE);
1391 @SuppressWarnings({"rawtypes","unchecked"})
1392 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1393 table = tab;
1394
1395 // Read the keys and values, and put the mappings in the HashMap
1396 for (int i = 0; i < mappings; i++) {
1397 @SuppressWarnings("unchecked")
1398 K key = (K) s.readObject();
1399 @SuppressWarnings("unchecked")
1400 V value = (V) s.readObject();
1401 putVal(hash(key), key, value, false, false);
1402 }
1403 }
1404 }
1405
1406 /* ------------------------------------------------------------ */
1407 // iterators
1408
1409 abstract class HashIterator {
1410 Node<K,V> next; // next entry to return
1411 Node<K,V> current; // current entry
1412 int expectedModCount; // for fast-fail
1413 int index; // current slot
1414
1415 HashIterator() {
1416 expectedModCount = modCount;
1417 Node<K,V>[] t = table;
1418 current = next = null;
1419 index = 0;
1420 if (t != null && size > 0) { // advance to first entry
1421 do {} while (index < t.length && (next = t[index++]) == null);
1422 }
1423 }
1424
1425 public final boolean hasNext() {
1426 return next != null;
1427 }
1428
1429 final Node<K,V> nextNode() {
1430 Node<K,V>[] t;
1431 Node<K,V> e = next;
1432 if (modCount != expectedModCount)
1433 throw new ConcurrentModificationException();
1434 if (e == null)
1435 throw new NoSuchElementException();
1436 if ((next = (current = e).next) == null && (t = table) != null) {
1437 do {} while (index < t.length && (next = t[index++]) == null);
1438 }
1439 return e;
1440 }
1441
1442 public final void remove() {
1443 Node<K,V> p = current;
1444 if (p == null)
1445 throw new IllegalStateException();
1446 if (modCount != expectedModCount)
1447 throw new ConcurrentModificationException();
1448 current = null;
1449 K key = p.key;
1450 removeNode(hash(key), key, null, false, false);
1451 expectedModCount = modCount;
1452 }
1453 }
1454
1455 final class KeyIterator extends HashIterator
1456 implements Iterator<K> {
1457 public final K next() { return nextNode().key; }
1458 }
1459
1460 final class ValueIterator extends HashIterator
1461 implements Iterator<V> {
1462 public final V next() { return nextNode().value; }
1463 }
1464
1465 final class EntryIterator extends HashIterator
1466 implements Iterator<Map.Entry<K,V>> {
1467 public final Map.Entry<K,V> next() { return nextNode(); }
1468 }
1469
1470 /* ------------------------------------------------------------ */
1471 // spliterators
1472
1473 static class HashMapSpliterator<K,V> {
1474 final HashMap<K,V> map;
1475 Node<K,V> current; // current node
1476 int index; // current index, modified on advance/split
1477 int fence; // one past last index
1478 int est; // size estimate
1479 int expectedModCount; // for comodification checks
1480
1481 HashMapSpliterator(HashMap<K,V> m, int origin,
1482 int fence, int est,
1483 int expectedModCount) {
1484 this.map = m;
1485 this.index = origin;
1486 this.fence = fence;
1487 this.est = est;
1488 this.expectedModCount = expectedModCount;
1489 }
1490
1491 final int getFence() { // initialize fence and size on first use
1492 int hi;
1493 if ((hi = fence) < 0) {
1494 HashMap<K,V> m = map;
1495 est = m.size;
1496 expectedModCount = m.modCount;
1497 Node<K,V>[] tab = m.table;
1498 hi = fence = (tab == null) ? 0 : tab.length;
1499 }
1500 return hi;
1501 }
1502
1503 public final long estimateSize() {
1504 getFence(); // force init
1505 return (long) est;
1506 }
1507 }
1508
1509 static final class KeySpliterator<K,V>
1510 extends HashMapSpliterator<K,V>
1511 implements Spliterator<K> {
1512 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1513 int expectedModCount) {
1514 super(m, origin, fence, est, expectedModCount);
1515 }
1516
1517 public KeySpliterator<K,V> trySplit() {
1518 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1519 return (lo >= mid || current != null) ? null :
1520 new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1521 expectedModCount);
1522 }
1523
1524 public void forEachRemaining(Consumer<? super K> action) {
1525 int i, hi, mc;
1526 if (action == null)
1527 throw new NullPointerException();
1528 HashMap<K,V> m = map;
1529 Node<K,V>[] tab = m.table;
1530 if ((hi = fence) < 0) {
1531 mc = expectedModCount = m.modCount;
1532 hi = fence = (tab == null) ? 0 : tab.length;
1533 }
1534 else
1535 mc = expectedModCount;
1536 if (tab != null && tab.length >= hi &&
1537 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1538 Node<K,V> p = current;
1539 current = null;
1540 do {
1541 if (p == null)
1542 p = tab[i++];
1543 else {
1544 action.accept(p.key);
1545 p = p.next;
1546 }
1547 } while (p != null || i < hi);
1548 if (m.modCount != mc)
1549 throw new ConcurrentModificationException();
1550 }
1551 }
1552
1553 public boolean tryAdvance(Consumer<? super K> action) {
1554 int hi;
1555 if (action == null)
1556 throw new NullPointerException();
1557 Node<K,V>[] tab = map.table;
1558 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1559 while (current != null || index < hi) {
1560 if (current == null)
1561 current = tab[index++];
1562 else {
1563 K k = current.key;
1564 current = current.next;
1565 action.accept(k);
1566 if (map.modCount != expectedModCount)
1567 throw new ConcurrentModificationException();
1568 return true;
1569 }
1570 }
1571 }
1572 return false;
1573 }
1574
1575 public int characteristics() {
1576 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1577 Spliterator.DISTINCT;
1578 }
1579 }
1580
1581 static final class ValueSpliterator<K,V>
1582 extends HashMapSpliterator<K,V>
1583 implements Spliterator<V> {
1584 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1585 int expectedModCount) {
1586 super(m, origin, fence, est, expectedModCount);
1587 }
1588
1589 public ValueSpliterator<K,V> trySplit() {
1590 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1591 return (lo >= mid || current != null) ? null :
1592 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1593 expectedModCount);
1594 }
1595
1596 public void forEachRemaining(Consumer<? super V> action) {
1597 int i, hi, mc;
1598 if (action == null)
1599 throw new NullPointerException();
1600 HashMap<K,V> m = map;
1601 Node<K,V>[] tab = m.table;
1602 if ((hi = fence) < 0) {
1603 mc = expectedModCount = m.modCount;
1604 hi = fence = (tab == null) ? 0 : tab.length;
1605 }
1606 else
1607 mc = expectedModCount;
1608 if (tab != null && tab.length >= hi &&
1609 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1610 Node<K,V> p = current;
1611 current = null;
1612 do {
1613 if (p == null)
1614 p = tab[i++];
1615 else {
1616 action.accept(p.value);
1617 p = p.next;
1618 }
1619 } while (p != null || i < hi);
1620 if (m.modCount != mc)
1621 throw new ConcurrentModificationException();
1622 }
1623 }
1624
1625 public boolean tryAdvance(Consumer<? super V> action) {
1626 int hi;
1627 if (action == null)
1628 throw new NullPointerException();
1629 Node<K,V>[] tab = map.table;
1630 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1631 while (current != null || index < hi) {
1632 if (current == null)
1633 current = tab[index++];
1634 else {
1635 V v = current.value;
1636 current = current.next;
1637 action.accept(v);
1638 if (map.modCount != expectedModCount)
1639 throw new ConcurrentModificationException();
1640 return true;
1641 }
1642 }
1643 }
1644 return false;
1645 }
1646
1647 public int characteristics() {
1648 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1649 }
1650 }
1651
1652 static final class EntrySpliterator<K,V>
1653 extends HashMapSpliterator<K,V>
1654 implements Spliterator<Map.Entry<K,V>> {
1655 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1656 int expectedModCount) {
1657 super(m, origin, fence, est, expectedModCount);
1658 }
1659
1660 public EntrySpliterator<K,V> trySplit() {
1661 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1662 return (lo >= mid || current != null) ? null :
1663 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1664 expectedModCount);
1665 }
1666
1667 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1668 int i, hi, mc;
1669 if (action == null)
1670 throw new NullPointerException();
1671 HashMap<K,V> m = map;
1672 Node<K,V>[] tab = m.table;
1673 if ((hi = fence) < 0) {
1674 mc = expectedModCount = m.modCount;
1675 hi = fence = (tab == null) ? 0 : tab.length;
1676 }
1677 else
1678 mc = expectedModCount;
1679 if (tab != null && tab.length >= hi &&
1680 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1681 Node<K,V> p = current;
1682 current = null;
1683 do {
1684 if (p == null)
1685 p = tab[i++];
1686 else {
1687 action.accept(p);
1688 p = p.next;
1689 }
1690 } while (p != null || i < hi);
1691 if (m.modCount != mc)
1692 throw new ConcurrentModificationException();
1693 }
1694 }
1695
1696 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1697 int hi;
1698 if (action == null)
1699 throw new NullPointerException();
1700 Node<K,V>[] tab = map.table;
1701 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1702 while (current != null || index < hi) {
1703 if (current == null)
1704 current = tab[index++];
1705 else {
1706 Node<K,V> e = current;
1707 current = current.next;
1708 action.accept(e);
1709 if (map.modCount != expectedModCount)
1710 throw new ConcurrentModificationException();
1711 return true;
1712 }
1713 }
1714 }
1715 return false;
1716 }
1717
1718 public int characteristics() {
1719 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1720 Spliterator.DISTINCT;
1721 }
1722 }
1723
1724 /* ------------------------------------------------------------ */
1725 // LinkedHashMap support
1726
1727
1728 /*
1729 * The following package-protected methods are designed to be
1730 * overridden by LinkedHashMap, but not by any other subclass.
1731 * Nearly all other internal methods are also package-protected
1732 * but are declared final, so can be used by LinkedHashMap, view
1733 * classes, and HashSet.
1734 */
1735
1736 // Create a regular (non-tree) node
1737 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1738 return new Node<>(hash, key, value, next);
1739 }
1740
1741 // For conversion from TreeNodes to plain nodes
1742 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1743 return new Node<>(p.hash, p.key, p.value, next);
1744 }
1745
1746 // Create a tree bin node
1747 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1748 return new TreeNode<>(hash, key, value, next);
1749 }
1750
1751 // For treeifyBin
1752 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1753 return new TreeNode<>(p.hash, p.key, p.value, next);
1754 }
1755
1756 /**
1757 * Reset to initial default state. Called by clone and readObject.
1758 */
1759 void reinitialize() {
1760 table = null;
1761 entrySet = null;
1762 keySet = null;
1763 values = null;
1764 modCount = 0;
1765 threshold = 0;
1766 size = 0;
1767 }
1768
1769 // Callbacks to allow LinkedHashMap post-actions
1770 void afterNodeAccess(Node<K,V> p) { }
1771 void afterNodeInsertion(boolean evict) { }
1772 void afterNodeRemoval(Node<K,V> p) { }
1773
1774 // Called only from writeObject, to ensure compatible ordering.
1775 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1776 Node<K,V>[] tab;
1777 if (size > 0 && (tab = table) != null) {
1778 for (Node<K, V> e : tab) {
1779 for (; e != null; e = e.next) {
1780 s.writeObject(e.key);
1781 s.writeObject(e.value);
1782 }
1783 }
1784 }
1785 }
1786
1787 /* ------------------------------------------------------------ */
1788 // Tree bins
1789
1790 /**
1791 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1792 * extends Node) so can be used as extension of either regular or
1793 * linked node.
1794 */
1795 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1796 TreeNode<K,V> parent; // red-black tree links
1797 TreeNode<K,V> left;
1798 TreeNode<K,V> right;
1799 TreeNode<K,V> prev; // needed to unlink next upon deletion
1800 boolean red;
1801 TreeNode(int hash, K key, V val, Node<K,V> next) {
1802 super(hash, key, val, next);
1803 }
1804
1805 /**
1806 * Returns root of tree containing this node.
1807 */
1808 final TreeNode<K,V> root() {
1809 for (TreeNode<K,V> r = this, p;;) {
1810 if ((p = r.parent) == null)
1811 return r;
1812 r = p;
1813 }
1814 }
1815
1816 /**
1817 * Ensures that the given root is the first node of its bin.
1818 */
1819 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1820 int n;
1821 if (root != null && tab != null && (n = tab.length) > 0) {
1822 int index = (n - 1) & root.hash;
1823 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1824 if (root != first) {
1825 Node<K,V> rn;
1826 tab[index] = root;
1827 TreeNode<K,V> rp = root.prev;
1828 if ((rn = root.next) != null)
1829 ((TreeNode<K,V>)rn).prev = rp;
1830 if (rp != null)
1831 rp.next = rn;
1832 if (first != null)
1833 first.prev = root;
1834 root.next = first;
1835 root.prev = null;
1836 }
1837 assert checkInvariants(root);
1838 }
1839 }
1840
1841 /**
1842 * Finds the node starting at root p with the given hash and key.
1843 * The kc argument caches comparableClassFor(key) upon first use
1844 * comparing keys.
1845 */
1846 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1847 TreeNode<K,V> p = this;
1848 do {
1849 int ph, dir; K pk;
1850 TreeNode<K,V> pl = p.left, pr = p.right, q;
1851 if ((ph = p.hash) > h)
1852 p = pl;
1853 else if (ph < h)
1854 p = pr;
1855 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1856 return p;
1857 else if (pl == null)
1858 p = pr;
1859 else if (pr == null)
1860 p = pl;
1861 else if ((kc = comparableClassFor(kc, k)) != void.class &&
1862 (dir = compareComparables(kc, k, pk)) != 0)
1863 p = (dir < 0) ? pl : pr;
1864 else if ((q = pr.find(h, k, kc)) != null)
1865 return q;
1866 else
1867 p = pl;
1868 } while (p != null);
1869 return null;
1870 }
1871
1872 /**
1873 * Calls find for root node.
1874 */
1875 final TreeNode<K,V> getTreeNode(int h, Object k) {
1876 return ((parent != null) ? root() : this).find(h, k, null);
1877 }
1878
1879 /**
1880 * Tie-breaking utility for ordering insertions when equal
1881 * hashCodes and non-comparable. We don't require a total
1882 * order, just a consistent insertion rule to maintain
1883 * equivalence across rebalancings. Tie-breaking further than
1884 * necessary simplifies testing a bit.
1885 */
1886 static int tieBreakOrder(Object a, Object b) {
1887 int d;
1888 if (a == null || b == null ||
1889 (d = a.getClass().getName().
1890 compareTo(b.getClass().getName())) == 0)
1891 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1892 -1 : 1);
1893 return d;
1894 }
1895
1896 /**
1897 * Forms tree of the nodes linked from this node.
1898 * @return root of tree
1899 */
1900 final void treeify(Node<K,V>[] tab) {
1901 TreeNode<K,V> root = null;
1902 for (TreeNode<K,V> x = this, next; x != null; x = next) {
1903 next = (TreeNode<K,V>)x.next;
1904 x.left = x.right = null;
1905 if (root == null) {
1906 x.parent = null;
1907 x.red = false;
1908 root = x;
1909 }
1910 else {
1911 K k = x.key;
1912 int h = x.hash;
1913 Class<?> kc = null;
1914 for (TreeNode<K,V> p = root;;) {
1915 int dir, ph;
1916 K pk = p.key;
1917 if ((ph = p.hash) > h)
1918 dir = -1;
1919 else if (ph < h)
1920 dir = 1;
1921 else if ((kc = comparableClassFor(kc, k)) == void.class ||
1922 (dir = compareComparables(kc, k, pk)) == 0)
1923 dir = tieBreakOrder(k, pk);
1924
1925 TreeNode<K,V> xp = p;
1926 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1927 x.parent = xp;
1928 if (dir <= 0)
1929 xp.left = x;
1930 else
1931 xp.right = x;
1932 root = balanceInsertion(root, x);
1933 break;
1934 }
1935 }
1936 }
1937 }
1938 moveRootToFront(tab, root);
1939 }
1940
1941 /**
1942 * Returns a list of non-TreeNodes replacing those linked from
1943 * this node.
1944 */
1945 final Node<K,V> untreeify(HashMap<K,V> map) {
1946 Node<K,V> hd = null, tl = null;
1947 for (Node<K,V> q = this; q != null; q = q.next) {
1948 Node<K,V> p = map.replacementNode(q, null);
1949 if (tl == null)
1950 hd = p;
1951 else
1952 tl.next = p;
1953 tl = p;
1954 }
1955 return hd;
1956 }
1957
1958 /**
1959 * Tree version of putVal.
1960 */
1961 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
1962 int h, K k, V v) {
1963 Class<?> kc = null;
1964 boolean searched = false;
1965 TreeNode<K,V> root = (parent != null) ? root() : this;
1966 for (TreeNode<K,V> p = root;;) {
1967 int dir, ph; K pk;
1968 if ((ph = p.hash) > h)
1969 dir = -1;
1970 else if (ph < h)
1971 dir = 1;
1972 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1973 return p;
1974 else if ((kc = comparableClassFor(kc, k)) == void.class ||
1975 (dir = compareComparables(kc, k, pk)) == 0) {
1976 if (!searched) {
1977 TreeNode<K,V> q, ch;
1978 searched = true;
1979 if (((ch = p.left) != null &&
1980 (q = ch.find(h, k, kc)) != null) ||
1981 ((ch = p.right) != null &&
1982 (q = ch.find(h, k, kc)) != null))
1983 return q;
1984 }
1985 dir = tieBreakOrder(k, pk);
1986 }
1987
1988 TreeNode<K,V> xp = p;
1989 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1990 Node<K,V> xpn = xp.next;
1991 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
1992 if (dir <= 0)
1993 xp.left = x;
1994 else
1995 xp.right = x;
1996 xp.next = x;
1997 x.parent = x.prev = xp;
1998 if (xpn != null)
1999 ((TreeNode<K,V>)xpn).prev = x;
2000 moveRootToFront(tab, balanceInsertion(root, x));
2001 return null;
2002 }
2003 }
2004 }
2005
2006 /**
2007 * Removes the given node, that must be present before this call.
2008 * This is messier than typical red-black deletion code because we
2009 * cannot swap the contents of an interior node with a leaf
2010 * successor that is pinned by "next" pointers that are accessible
2011 * independently during traversal. So instead we swap the tree
2012 * linkages. If the current tree appears to have too few nodes,
2013 * the bin is converted back to a plain bin. (The test triggers
2014 * somewhere between 2 and 6 nodes, depending on tree structure).
2015 */
2016 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2017 boolean movable) {
2018 int n;
2019 if (tab == null || (n = tab.length) == 0)
2020 return;
2021 int index = (n - 1) & hash;
2022 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2023 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2024 if (pred == null)
2025 tab[index] = first = succ;
2026 else
2027 pred.next = succ;
2028 if (succ != null)
2029 succ.prev = pred;
2030 if (first == null)
2031 return;
2032 if (root.parent != null)
2033 root = root.root();
2034 if (root == null || root.right == null ||
2035 (rl = root.left) == null || rl.left == null) {
2036 tab[index] = first.untreeify(map); // too small
2037 return;
2038 }
2039 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2040 if (pl != null && pr != null) {
2041 TreeNode<K,V> s = pr, sl;
2042 while ((sl = s.left) != null) // find successor
2043 s = sl;
2044 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2045 TreeNode<K,V> sr = s.right;
2046 TreeNode<K,V> pp = p.parent;
2047 if (s == pr) { // p was s's direct parent
2048 p.parent = s;
2049 s.right = p;
2050 }
2051 else {
2052 TreeNode<K,V> sp = s.parent;
2053 if ((p.parent = sp) != null) {
2054 if (s == sp.left)
2055 sp.left = p;
2056 else
2057 sp.right = p;
2058 }
2059 if ((s.right = pr) != null)
2060 pr.parent = s;
2061 }
2062 p.left = null;
2063 if ((p.right = sr) != null)
2064 sr.parent = p;
2065 if ((s.left = pl) != null)
2066 pl.parent = s;
2067 if ((s.parent = pp) == null)
2068 root = s;
2069 else if (p == pp.left)
2070 pp.left = s;
2071 else
2072 pp.right = s;
2073 if (sr != null)
2074 replacement = sr;
2075 else
2076 replacement = p;
2077 }
2078 else if (pl != null)
2079 replacement = pl;
2080 else if (pr != null)
2081 replacement = pr;
2082 else
2083 replacement = p;
2084 if (replacement != p) {
2085 TreeNode<K,V> pp = replacement.parent = p.parent;
2086 if (pp == null)
2087 root = replacement;
2088 else if (p == pp.left)
2089 pp.left = replacement;
2090 else
2091 pp.right = replacement;
2092 p.left = p.right = p.parent = null;
2093 }
2094
2095 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2096
2097 if (replacement == p) { // detach
2098 TreeNode<K,V> pp = p.parent;
2099 p.parent = null;
2100 if (pp != null) {
2101 if (p == pp.left)
2102 pp.left = null;
2103 else if (p == pp.right)
2104 pp.right = null;
2105 }
2106 }
2107 if (movable)
2108 moveRootToFront(tab, r);
2109 }
2110
2111 /**
2112 * Splits nodes in a tree bin into lower and upper tree bins,
2113 * or untreeifies if now too small. Called only from resize;
2114 * see above discussion about split bits and indices.
2115 *
2116 * @param map the map
2117 * @param tab the table for recording bin heads
2118 * @param index the index of the table being split
2119 * @param bit the bit of hash to split on
2120 */
2121 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2122 TreeNode<K,V> b = this;
2123 // Relink into lo and hi lists, preserving order
2124 TreeNode<K,V> loHead = null, loTail = null;
2125 TreeNode<K,V> hiHead = null, hiTail = null;
2126 int lc = 0, hc = 0;
2127 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2128 next = (TreeNode<K,V>)e.next;
2129 e.next = null;
2130 if ((e.hash & bit) == 0) {
2131 if ((e.prev = loTail) == null)
2132 loHead = e;
2133 else
2134 loTail.next = e;
2135 loTail = e;
2136 ++lc;
2137 }
2138 else {
2139 if ((e.prev = hiTail) == null)
2140 hiHead = e;
2141 else
2142 hiTail.next = e;
2143 hiTail = e;
2144 ++hc;
2145 }
2146 }
2147
2148 if (loHead != null) {
2149 if (lc <= UNTREEIFY_THRESHOLD)
2150 tab[index] = loHead.untreeify(map);
2151 else {
2152 tab[index] = loHead;
2153 if (hiHead != null) // (else is already treeified)
2154 loHead.treeify(tab);
2155 }
2156 }
2157 if (hiHead != null) {
2158 if (hc <= UNTREEIFY_THRESHOLD)
2159 tab[index + bit] = hiHead.untreeify(map);
2160 else {
2161 tab[index + bit] = hiHead;
2162 if (loHead != null)
2163 hiHead.treeify(tab);
2164 }
2165 }
2166 }
2167
2168 /* ------------------------------------------------------------ */
2169 // Red-black tree methods, all adapted from CLR
2170
2171 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2172 TreeNode<K,V> p) {
2173 TreeNode<K,V> r, pp, rl;
2174 if (p != null && (r = p.right) != null) {
2175 if ((rl = p.right = r.left) != null)
2176 rl.parent = p;
2177 if ((pp = r.parent = p.parent) == null)
2178 (root = r).red = false;
2179 else if (pp.left == p)
2180 pp.left = r;
2181 else
2182 pp.right = r;
2183 r.left = p;
2184 p.parent = r;
2185 }
2186 return root;
2187 }
2188
2189 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2190 TreeNode<K,V> p) {
2191 TreeNode<K,V> l, pp, lr;
2192 if (p != null && (l = p.left) != null) {
2193 if ((lr = p.left = l.right) != null)
2194 lr.parent = p;
2195 if ((pp = l.parent = p.parent) == null)
2196 (root = l).red = false;
2197 else if (pp.right == p)
2198 pp.right = l;
2199 else
2200 pp.left = l;
2201 l.right = p;
2202 p.parent = l;
2203 }
2204 return root;
2205 }
2206
2207 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2208 TreeNode<K,V> x) {
2209 x.red = true;
2210 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2211 if ((xp = x.parent) == null) {
2212 x.red = false;
2213 return x;
2214 }
2215 else if (!xp.red || (xpp = xp.parent) == null)
2216 return root;
2217 if (xp == (xppl = xpp.left)) {
2218 if ((xppr = xpp.right) != null && xppr.red) {
2219 xppr.red = false;
2220 xp.red = false;
2221 xpp.red = true;
2222 x = xpp;
2223 }
2224 else {
2225 if (x == xp.right) {
2226 root = rotateLeft(root, x = xp);
2227 xpp = (xp = x.parent) == null ? null : xp.parent;
2228 }
2229 if (xp != null) {
2230 xp.red = false;
2231 if (xpp != null) {
2232 xpp.red = true;
2233 root = rotateRight(root, xpp);
2234 }
2235 }
2236 }
2237 }
2238 else {
2239 if (xppl != null && xppl.red) {
2240 xppl.red = false;
2241 xp.red = false;
2242 xpp.red = true;
2243 x = xpp;
2244 }
2245 else {
2246 if (x == xp.left) {
2247 root = rotateRight(root, x = xp);
2248 xpp = (xp = x.parent) == null ? null : xp.parent;
2249 }
2250 if (xp != null) {
2251 xp.red = false;
2252 if (xpp != null) {
2253 xpp.red = true;
2254 root = rotateLeft(root, xpp);
2255 }
2256 }
2257 }
2258 }
2259 }
2260 }
2261
2262 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2263 TreeNode<K,V> x) {
2264 for (TreeNode<K,V> xp, xpl, xpr;;) {
2265 if (x == null || x == root)
2266 return root;
2267 else if ((xp = x.parent) == null) {
2268 x.red = false;
2269 return x;
2270 }
2271 else if (x.red) {
2272 x.red = false;
2273 return root;
2274 }
2275 else if ((xpl = xp.left) == x) {
2276 if ((xpr = xp.right) != null && xpr.red) {
2277 xpr.red = false;
2278 xp.red = true;
2279 root = rotateLeft(root, xp);
2280 xpr = (xp = x.parent) == null ? null : xp.right;
2281 }
2282 if (xpr == null)
2283 x = xp;
2284 else {
2285 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2286 if ((sr == null || !sr.red) &&
2287 (sl == null || !sl.red)) {
2288 xpr.red = true;
2289 x = xp;
2290 }
2291 else {
2292 if (sr == null || !sr.red) {
2293 if (sl != null)
2294 sl.red = false;
2295 xpr.red = true;
2296 root = rotateRight(root, xpr);
2297 xpr = (xp = x.parent) == null ?
2298 null : xp.right;
2299 }
2300 if (xpr != null) {
2301 xpr.red = (xp == null) ? false : xp.red;
2302 if ((sr = xpr.right) != null)
2303 sr.red = false;
2304 }
2305 if (xp != null) {
2306 xp.red = false;
2307 root = rotateLeft(root, xp);
2308 }
2309 x = root;
2310 }
2311 }
2312 }
2313 else { // symmetric
2314 if (xpl != null && xpl.red) {
2315 xpl.red = false;
2316 xp.red = true;
2317 root = rotateRight(root, xp);
2318 xpl = (xp = x.parent) == null ? null : xp.left;
2319 }
2320 if (xpl == null)
2321 x = xp;
2322 else {
2323 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2324 if ((sl == null || !sl.red) &&
2325 (sr == null || !sr.red)) {
2326 xpl.red = true;
2327 x = xp;
2328 }
2329 else {
2330 if (sl == null || !sl.red) {
2331 if (sr != null)
2332 sr.red = false;
2333 xpl.red = true;
2334 root = rotateLeft(root, xpl);
2335 xpl = (xp = x.parent) == null ?
2336 null : xp.left;
2337 }
2338 if (xpl != null) {
2339 xpl.red = (xp == null) ? false : xp.red;
2340 if ((sl = xpl.left) != null)
2341 sl.red = false;
2342 }
2343 if (xp != null) {
2344 xp.red = false;
2345 root = rotateRight(root, xp);
2346 }
2347 x = root;
2348 }
2349 }
2350 }
2351 }
2352 }
2353
2354 /**
2355 * Recursive invariant check
2356 */
2357 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2358 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2359 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2360 if (tb != null && tb.next != t)
2361 return false;
2362 if (tn != null && tn.prev != t)
2363 return false;
2364 if (tp != null && t != tp.left && t != tp.right)
2365 return false;
2366 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2367 return false;
2368 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2369 return false;
2370 if (t.red && tl != null && tl.red && tr != null && tr.red)
2371 return false;
2372 if (tl != null && !checkInvariants(tl))
2373 return false;
2374 if (tr != null && !checkInvariants(tr))
2375 return false;
2376 return true;
2377 }
2378 }
2379
2380 }