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