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 x's Class if it is of the form "class C implements
343 * Comparable<C>", else null.
344 */
345 static Class<?> comparableClassFor(Object x) {
346 if (x instanceof Comparable) {
347 Class<?> c; Type[] ts, as; Type t; ParameterizedType p;
348 if ((c = x.getClass()) == String.class) // bypass checks
349 return c;
350 if ((ts = c.getGenericInterfaces()) != null) {
351 for (int i = 0; i < ts.length; ++i) {
352 if (((t = ts[i]) instanceof ParameterizedType) &&
353 ((p = (ParameterizedType)t).getRawType() ==
354 Comparable.class) &&
355 (as = p.getActualTypeArguments()) != null &&
356 as.length == 1 && as[0] == c) // type arg is c
357 return c;
358 }
359 }
360 }
361 return null;
362 }
363
364 /**
365 * Returns k.compareTo(x) if x matches kc (k's screened comparable
366 * class), else 0.
367 */
368 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
369 static int compareComparables(Class<?> kc, Object k, Object x) {
370 return (x == null || x.getClass() != kc ? 0 :
371 ((Comparable)k).compareTo(x));
372 }
373
374 /**
375 * Returns a power of two size for the given target capacity.
376 */
377 static final int tableSizeFor(int cap) {
378 int n = cap - 1;
379 n |= n >>> 1;
380 n |= n >>> 2;
381 n |= n >>> 4;
382 n |= n >>> 8;
383 n |= n >>> 16;
384 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
385 }
386
387 /* ---------------- Fields -------------- */
388
389 /**
390 * The table, initialized on first use, and resized as
391 * necessary. When allocated, length is always a power of two.
392 * (We also tolerate length zero in some operations to allow
393 * bootstrapping mechanics that are currently not needed.)
394 */
395 transient Node<K,V>[] table;
396
397 /**
398 * Holds cached entrySet(). Note that AbstractMap fields are used
399 * for keySet() and values().
400 */
401 transient Set<Map.Entry<K,V>> entrySet;
402
403 /**
404 * The number of key-value mappings contained in this map.
405 */
406 transient int size;
407
408 /**
409 * The number of times this HashMap has been structurally modified
410 * Structural modifications are those that change the number of mappings in
411 * the HashMap or otherwise modify its internal structure (e.g.,
412 * rehash). This field is used to make iterators on Collection-views of
413 * the HashMap fail-fast. (See ConcurrentModificationException).
414 */
415 transient int modCount;
416
417 /**
418 * The next size value at which to resize (capacity * load factor).
419 *
420 * @serial
421 */
422 // (The javadoc description is true upon serialization.
423 // Additionally, if the table array has not been allocated, this
424 // field holds the initial array capacity, or zero signifying
425 // DEFAULT_INITIAL_CAPACITY.)
426 int threshold;
427
428 /**
429 * The load factor for the hash table.
430 *
431 * @serial
432 */
433 final float loadFactor;
434
435 /* ---------------- Public operations -------------- */
436
437 /**
438 * Constructs an empty <tt>HashMap</tt> with the specified initial
439 * capacity and load factor.
440 *
441 * @param initialCapacity the initial capacity
442 * @param loadFactor the load factor
443 * @throws IllegalArgumentException if the initial capacity is negative
444 * or the load factor is nonpositive
445 */
446 public HashMap(int initialCapacity, float loadFactor) {
447 if (initialCapacity < 0)
448 throw new IllegalArgumentException("Illegal initial capacity: " +
449 initialCapacity);
450 if (initialCapacity > MAXIMUM_CAPACITY)
451 initialCapacity = MAXIMUM_CAPACITY;
452 if (loadFactor <= 0 || Float.isNaN(loadFactor))
453 throw new IllegalArgumentException("Illegal load factor: " +
454 loadFactor);
455 this.loadFactor = loadFactor;
456 this.threshold = tableSizeFor(initialCapacity);
457 }
458
459 /**
460 * Constructs an empty <tt>HashMap</tt> with the specified initial
461 * capacity and the default load factor (0.75).
462 *
463 * @param initialCapacity the initial capacity.
464 * @throws IllegalArgumentException if the initial capacity is negative.
465 */
466 public HashMap(int initialCapacity) {
467 this(initialCapacity, DEFAULT_LOAD_FACTOR);
468 }
469
470 /**
471 * Constructs an empty <tt>HashMap</tt> with the default initial capacity
472 * (16) and the default load factor (0.75).
473 */
474 public HashMap() {
475 this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
476 }
477
478 /**
479 * Constructs a new <tt>HashMap</tt> with the same mappings as the
480 * specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
481 * default load factor (0.75) and an initial capacity sufficient to
482 * hold the mappings in the specified <tt>Map</tt>.
483 *
484 * @param m the map whose mappings are to be placed in this map
485 * @throws NullPointerException if the specified map is null
486 */
487 public HashMap(Map<? extends K, ? extends V> m) {
488 this.loadFactor = DEFAULT_LOAD_FACTOR;
489 putMapEntries(m, false);
490 }
491
492 /**
493 * Implements Map.putAll and Map constructor
494 *
495 * @param m the map
496 * @param evict false when initially constructing this map, else
497 * true (relayed to method afterNodeInsertion).
498 */
499 final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
500 int s = m.size();
501 if (s > 0) {
502 if (table == null) { // pre-size
503 float ft = ((float)s / loadFactor) + 1.0F;
504 int t = ((ft < (float)MAXIMUM_CAPACITY) ?
505 (int)ft : MAXIMUM_CAPACITY);
506 if (t > threshold)
507 threshold = tableSizeFor(t);
508 }
509 else if (s > threshold)
510 resize();
511 for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
512 K key = e.getKey();
513 V value = e.getValue();
514 putVal(hash(key), key, value, false, evict);
515 }
516 }
517 }
518
519 /**
520 * Returns the number of key-value mappings in this map.
521 *
522 * @return the number of key-value mappings in this map
523 */
524 public int size() {
525 return size;
526 }
527
528 /**
529 * Returns <tt>true</tt> if this map contains no key-value mappings.
530 *
531 * @return <tt>true</tt> if this map contains no key-value mappings
532 */
533 public boolean isEmpty() {
534 return size == 0;
535 }
536
537 /**
538 * Returns the value to which the specified key is mapped,
539 * or {@code null} if this map contains no mapping for the key.
540 *
541 * <p>More formally, if this map contains a mapping from a key
542 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
543 * key.equals(k))}, then this method returns {@code v}; otherwise
544 * it returns {@code null}. (There can be at most one such mapping.)
545 *
546 * <p>A return value of {@code null} does not <i>necessarily</i>
547 * indicate that the map contains no mapping for the key; it's also
548 * possible that the map explicitly maps the key to {@code null}.
549 * The {@link #containsKey containsKey} operation may be used to
550 * distinguish these two cases.
551 *
552 * @see #put(Object, Object)
553 */
554 public V get(Object key) {
555 Node<K,V> e;
556 return (e = getNode(hash(key), key)) == null ? null : e.value;
557 }
558
559 /**
560 * Implements Map.get and related methods
561 *
562 * @param hash hash for key
563 * @param key the key
564 * @return the node, or null if none
565 */
566 final Node<K,V> getNode(int hash, Object key) {
567 Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
568 if ((tab = table) != null && (n = tab.length) > 0 &&
569 (first = tab[(n - 1) & hash]) != null) {
570 if (first.hash == hash && // always check first node
571 ((k = first.key) == key || (key != null && key.equals(k))))
572 return first;
573 if ((e = first.next) != null) {
574 if (first instanceof TreeNode)
575 return ((TreeNode<K,V>)first).getTreeNode(hash, key);
576 do {
577 if (e.hash == hash &&
578 ((k = e.key) == key || (key != null && key.equals(k))))
579 return e;
580 } while ((e = e.next) != null);
581 }
582 }
583 return null;
584 }
585
586 /**
587 * Returns <tt>true</tt> if this map contains a mapping for the
588 * specified key.
589 *
590 * @param key The key whose presence in this map is to be tested
591 * @return <tt>true</tt> if this map contains a mapping for the specified
592 * key.
593 */
594 public boolean containsKey(Object key) {
595 return getNode(hash(key), key) != null;
596 }
597
598 /**
599 * Associates the specified value with the specified key in this map.
600 * If the map previously contained a mapping for the key, the old
601 * value is replaced.
602 *
603 * @param key key with which the specified value is to be associated
604 * @param value value to be associated with the specified key
605 * @return the previous value associated with <tt>key</tt>, or
606 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
607 * (A <tt>null</tt> return can also indicate that the map
608 * previously associated <tt>null</tt> with <tt>key</tt>.)
609 */
610 public V put(K key, V value) {
611 return putVal(hash(key), key, value, false, true);
612 }
613
614 /**
615 * Implements Map.put and related methods
616 *
617 * @param hash hash for key
618 * @param key the key
619 * @param value the value to put
620 * @param onlyIfAbsent if true, don't change existing value
621 * @param evict if false, the table is in creation mode.
622 * @return previous value, or null if none
623 */
624 final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
625 boolean evict) {
626 Node<K,V>[] tab; Node<K,V> p; int n, i;
627 if ((tab = table) == null || (n = tab.length) == 0)
628 n = (tab = resize()).length;
629 if ((p = tab[i = (n - 1) & hash]) == null)
630 tab[i] = newNode(hash, key, value, null);
631 else {
632 Node<K,V> e; K k;
633 if (p.hash == hash &&
634 ((k = p.key) == key || (key != null && key.equals(k))))
635 e = p;
636 else if (p instanceof TreeNode)
637 e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
638 else {
639 for (int binCount = 0; ; ++binCount) {
640 if ((e = p.next) == null) {
641 p.next = newNode(hash, key, value, null);
642 if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
643 treeifyBin(tab, hash);
644 break;
645 }
646 if (e.hash == hash &&
647 ((k = e.key) == key || (key != null && key.equals(k))))
648 break;
649 p = e;
650 }
651 }
652 if (e != null) { // existing mapping for key
653 V oldValue = e.value;
654 if (!onlyIfAbsent || oldValue == null)
655 e.value = value;
656 afterNodeAccess(e);
657 return oldValue;
658 }
659 }
660 ++modCount;
661 if (++size > threshold)
662 resize();
663 afterNodeInsertion(evict);
664 return null;
665 }
666
667 /**
668 * Initializes or doubles table size. If null, allocates in
669 * accord with initial capacity target held in field threshold.
670 * Otherwise, because we are using power-of-two expansion, the
671 * elements from each bin must either stay at same index, or move
672 * with a power of two offset in the new table.
673 *
674 * @return the table
675 */
676 final Node<K,V>[] resize() {
677 Node<K,V>[] oldTab = table;
678 int oldCap = (oldTab == null) ? 0 : oldTab.length;
679 int oldThr = threshold;
680 int newCap, newThr = 0;
681 if (oldCap > 0) {
682 if (oldCap >= MAXIMUM_CAPACITY) {
683 threshold = Integer.MAX_VALUE;
684 return oldTab;
685 }
686 else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
687 oldCap >= DEFAULT_INITIAL_CAPACITY)
688 newThr = oldThr << 1; // double threshold
689 }
690 else if (oldThr > 0) // initial capacity was placed in threshold
691 newCap = oldThr;
692 else { // zero initial threshold signifies using defaults
693 newCap = DEFAULT_INITIAL_CAPACITY;
694 newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
695 }
696 if (newThr == 0) {
697 float ft = (float)newCap * loadFactor;
698 newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
699 (int)ft : Integer.MAX_VALUE);
700 }
701 threshold = newThr;
702 @SuppressWarnings({"rawtypes","unchecked"})
703 Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
704 table = newTab;
705 if (oldTab != null) {
706 for (int j = 0; j < oldCap; ++j) {
707 Node<K,V> e;
708 if ((e = oldTab[j]) != null) {
709 oldTab[j] = null;
710 if (e.next == null)
711 newTab[e.hash & (newCap - 1)] = e;
712 else if (e instanceof TreeNode)
713 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
714 else { // preserve order
715 Node<K,V> loHead = null, loTail = null;
716 Node<K,V> hiHead = null, hiTail = null;
717 Node<K,V> next;
718 do {
719 next = e.next;
720 if ((e.hash & oldCap) == 0) {
721 if (loTail == null)
722 loHead = e;
723 else
724 loTail.next = e;
725 loTail = e;
726 }
727 else {
728 if (hiTail == null)
729 hiHead = e;
730 else
731 hiTail.next = e;
732 hiTail = e;
733 }
734 } while ((e = next) != null);
735 if (loTail != null) {
736 loTail.next = null;
737 newTab[j] = loHead;
738 }
739 if (hiTail != null) {
740 hiTail.next = null;
741 newTab[j + oldCap] = hiHead;
742 }
743 }
744 }
745 }
746 }
747 return newTab;
748 }
749
750 /**
751 * Replaces all linked nodes in bin at index for given hash unless
752 * table is too small, in which case resizes instead.
753 */
754 final void treeifyBin(Node<K,V>[] tab, int hash) {
755 int n, index; Node<K,V> e;
756 if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
757 resize();
758 else if ((e = tab[index = (n - 1) & hash]) != null) {
759 TreeNode<K,V> hd = null, tl = null;
760 do {
761 TreeNode<K,V> p = replacementTreeNode(e, null);
762 if (tl == null)
763 hd = p;
764 else {
765 p.prev = tl;
766 tl.next = p;
767 }
768 tl = p;
769 } while ((e = e.next) != null);
770 if ((tab[index] = hd) != null)
771 hd.treeify(tab);
772 }
773 }
774
775 /**
776 * Copies all of the mappings from the specified map to this map.
777 * These mappings will replace any mappings that this map had for
778 * any of the keys currently in the specified map.
779 *
780 * @param m mappings to be stored in this map
781 * @throws NullPointerException if the specified map is null
782 */
783 public void putAll(Map<? extends K, ? extends V> m) {
784 putMapEntries(m, true);
785 }
786
787 /**
788 * Removes the mapping for the specified key from this map if present.
789 *
790 * @param key key whose mapping is to be removed from the map
791 * @return the previous value associated with <tt>key</tt>, or
792 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
793 * (A <tt>null</tt> return can also indicate that the map
794 * previously associated <tt>null</tt> with <tt>key</tt>.)
795 */
796 public V remove(Object key) {
797 Node<K,V> e;
798 return (e = removeNode(hash(key), key, null, false, true)) == null ?
799 null : e.value;
800 }
801
802 /**
803 * Implements Map.remove and related methods
804 *
805 * @param hash hash for key
806 * @param key the key
807 * @param value the value to match if matchValue, else ignored
808 * @param matchValue if true only remove if value is equal
809 * @param movable if false do not move other nodes while removing
810 * @return the node, or null if none
811 */
812 final Node<K,V> removeNode(int hash, Object key, Object value,
813 boolean matchValue, boolean movable) {
814 Node<K,V>[] tab; Node<K,V> p; int n, index;
815 if ((tab = table) != null && (n = tab.length) > 0 &&
816 (p = tab[index = (n - 1) & hash]) != null) {
817 Node<K,V> node = null, e; K k; V v;
818 if (p.hash == hash &&
819 ((k = p.key) == key || (key != null && key.equals(k))))
820 node = p;
821 else if ((e = p.next) != null) {
822 if (p instanceof TreeNode)
823 node = ((TreeNode<K,V>)p).getTreeNode(hash, key);
824 else {
825 do {
826 if (e.hash == hash &&
827 ((k = e.key) == key ||
828 (key != null && key.equals(k)))) {
829 node = e;
830 break;
831 }
832 p = e;
833 } while ((e = e.next) != null);
834 }
835 }
836 if (node != null && (!matchValue || (v = node.value) == value ||
837 (value != null && value.equals(v)))) {
838 if (node instanceof TreeNode)
839 ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable);
840 else if (node == p)
841 tab[index] = node.next;
842 else
843 p.next = node.next;
844 ++modCount;
845 --size;
846 afterNodeRemoval(node);
847 return node;
848 }
849 }
850 return null;
851 }
852
853 /**
854 * Removes all of the mappings from this map.
855 * The map will be empty after this call returns.
856 */
857 public void clear() {
858 Node<K,V>[] tab;
859 modCount++;
860 if ((tab = table) != null && size > 0) {
861 size = 0;
862 for (int i = 0; i < tab.length; ++i)
863 tab[i] = null;
864 }
865 }
866
867 /**
868 * Returns <tt>true</tt> if this map maps one or more keys to the
869 * specified value.
870 *
871 * @param value value whose presence in this map is to be tested
872 * @return <tt>true</tt> if this map maps one or more keys to the
873 * specified value
874 */
875 public boolean containsValue(Object value) {
876 Node<K,V>[] tab; V v;
877 if ((tab = table) != null && size > 0) {
878 for (int i = 0; i < tab.length; ++i) {
879 for (Node<K,V> e = tab[i]; e != null; e = e.next) {
880 if ((v = e.value) == value ||
881 (value != null && value.equals(v)))
882 return true;
883 }
884 }
885 }
886 return false;
887 }
888
889 /**
890 * Returns a {@link Set} view of the keys contained in this map.
891 * The set is backed by the map, so changes to the map are
892 * reflected in the set, and vice-versa. If the map is modified
893 * while an iteration over the set is in progress (except through
894 * the iterator's own <tt>remove</tt> operation), the results of
895 * the iteration are undefined. The set supports element removal,
896 * which removes the corresponding mapping from the map, via the
897 * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
898 * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
899 * operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
900 * operations.
901 *
902 * @return a set view of the keys contained in this map
903 */
904 public Set<K> keySet() {
905 Set<K> ks = keySet;
906 if (ks == null) {
907 ks = new KeySet();
908 keySet = ks;
909 }
910 return ks;
911 }
912
913 final class KeySet extends AbstractSet<K> {
914 public final int size() { return size; }
915 public final void clear() { HashMap.this.clear(); }
916 public final Iterator<K> iterator() { return new KeyIterator(); }
917 public final boolean contains(Object o) { return containsKey(o); }
918 public final boolean remove(Object key) {
919 return removeNode(hash(key), key, null, false, true) != null;
920 }
921 public final Spliterator<K> spliterator() {
922 return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
923 }
924 public final void forEach(Consumer<? super K> action) {
925 Node<K,V>[] tab;
926 if (action == null)
927 throw new NullPointerException();
928 if (size > 0 && (tab = table) != null) {
929 int mc = modCount;
930 for (int i = 0; i < tab.length; ++i) {
931 for (Node<K,V> e = tab[i]; 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 = values;
957 if (vs == null) {
958 vs = new Values();
959 values = vs;
960 }
961 return vs;
962 }
963
964 final class Values extends AbstractCollection<V> {
965 public final int size() { return size; }
966 public final void clear() { HashMap.this.clear(); }
967 public final Iterator<V> iterator() { return new ValueIterator(); }
968 public final boolean contains(Object o) { return containsValue(o); }
969 public final Spliterator<V> spliterator() {
970 return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
971 }
972 public final void forEach(Consumer<? super V> action) {
973 Node<K,V>[] tab;
974 if (action == null)
975 throw new NullPointerException();
976 if (size > 0 && (tab = table) != null) {
977 int mc = modCount;
978 for (int i = 0; i < tab.length; ++i) {
979 for (Node<K,V> e = tab[i]; e != null; e = e.next)
980 action.accept(e.value);
981 }
982 if (modCount != mc)
983 throw new ConcurrentModificationException();
984 }
985 }
986 }
987
988 /**
989 * Returns a {@link Set} view of the mappings contained in this map.
990 * The set is backed by the map, so changes to the map are
991 * reflected in the set, and vice-versa. If the map is modified
992 * while an iteration over the set is in progress (except through
993 * the iterator's own <tt>remove</tt> operation, or through the
994 * <tt>setValue</tt> operation on a map entry returned by the
995 * iterator) the results of the iteration are undefined. The set
996 * supports element removal, which removes the corresponding
997 * mapping from the map, via the <tt>Iterator.remove</tt>,
998 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
999 * <tt>clear</tt> operations. It does not support the
1000 * <tt>add</tt> or <tt>addAll</tt> operations.
1001 *
1002 * @return a set view of the mappings contained in this map
1003 */
1004 public Set<Map.Entry<K,V>> entrySet() {
1005 Set<Map.Entry<K,V>> es;
1006 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
1007 }
1008
1009 final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1010 public final int size() { return size; }
1011 public final void clear() { HashMap.this.clear(); }
1012 public final Iterator<Map.Entry<K,V>> iterator() {
1013 return new EntryIterator();
1014 }
1015 public final boolean contains(Object o) {
1016 if (!(o instanceof Map.Entry))
1017 return false;
1018 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1019 Object key = e.getKey();
1020 Node<K,V> candidate = getNode(hash(key), key);
1021 return candidate != null && candidate.equals(e);
1022 }
1023 public final boolean remove(Object o) {
1024 if (o instanceof Map.Entry) {
1025 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1026 Object key = e.getKey();
1027 Object value = e.getValue();
1028 return removeNode(hash(key), key, value, true, true) != null;
1029 }
1030 return false;
1031 }
1032 public final Spliterator<Map.Entry<K,V>> spliterator() {
1033 return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
1034 }
1035 public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1036 Node<K,V>[] tab;
1037 if (action == null)
1038 throw new NullPointerException();
1039 if (size > 0 && (tab = table) != null) {
1040 int mc = modCount;
1041 for (int i = 0; i < tab.length; ++i) {
1042 for (Node<K,V> e = tab[i]; e != null; e = e.next)
1043 action.accept(e);
1044 }
1045 if (modCount != mc)
1046 throw new ConcurrentModificationException();
1047 }
1048 }
1049 }
1050
1051 // Overrides of JDK8 Map extension methods
1052
1053 @Override
1054 public V getOrDefault(Object key, V defaultValue) {
1055 Node<K,V> e;
1056 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1057 }
1058
1059 @Override
1060 public V putIfAbsent(K key, V value) {
1061 return putVal(hash(key), key, value, true, true);
1062 }
1063
1064 @Override
1065 public boolean remove(Object key, Object value) {
1066 return removeNode(hash(key), key, value, true, true) != null;
1067 }
1068
1069 @Override
1070 public boolean replace(K key, V oldValue, V newValue) {
1071 Node<K,V> e; V v;
1072 if ((e = getNode(hash(key), key)) != null &&
1073 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1074 e.value = newValue;
1075 afterNodeAccess(e);
1076 return true;
1077 }
1078 return false;
1079 }
1080
1081 @Override
1082 public V replace(K key, V value) {
1083 Node<K,V> e;
1084 if ((e = getNode(hash(key), key)) != null) {
1085 V oldValue = e.value;
1086 e.value = value;
1087 afterNodeAccess(e);
1088 return oldValue;
1089 }
1090 return null;
1091 }
1092
1093 @Override
1094 public V computeIfAbsent(K key,
1095 Function<? super K, ? extends V> mappingFunction) {
1096 if (mappingFunction == null)
1097 throw new NullPointerException();
1098 int hash = hash(key);
1099 Node<K,V>[] tab; Node<K,V> first; int n, i;
1100 int binCount = 0;
1101 TreeNode<K,V> t = null;
1102 Node<K,V> old = null;
1103 if (size > threshold || (tab = table) == null ||
1104 (n = tab.length) == 0)
1105 n = (tab = resize()).length;
1106 if ((first = tab[i = (n - 1) & hash]) != null) {
1107 if (first instanceof TreeNode)
1108 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1109 else {
1110 Node<K,V> e = first; K k;
1111 do {
1112 if (e.hash == hash &&
1113 ((k = e.key) == key || (key != null && key.equals(k)))) {
1114 old = e;
1115 break;
1116 }
1117 ++binCount;
1118 } while ((e = e.next) != null);
1119 }
1120 V oldValue;
1121 if (old != null && (oldValue = old.value) != null) {
1122 afterNodeAccess(old);
1123 return oldValue;
1124 }
1125 }
1126 V v = mappingFunction.apply(key);
1127 if (v == null) {
1128 return null;
1129 } else if (old != null) {
1130 old.value = v;
1131 afterNodeAccess(old);
1132 return v;
1133 }
1134 else if (t != null)
1135 t.putTreeVal(this, tab, hash, key, v);
1136 else {
1137 tab[i] = newNode(hash, key, v, first);
1138 if (binCount >= TREEIFY_THRESHOLD - 1)
1139 treeifyBin(tab, hash);
1140 }
1141 ++modCount;
1142 ++size;
1143 afterNodeInsertion(true);
1144 return v;
1145 }
1146
1147 public V computeIfPresent(K key,
1148 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1149 if (remappingFunction == null)
1150 throw new NullPointerException();
1151 Node<K,V> e; V oldValue;
1152 int hash = hash(key);
1153 if ((e = getNode(hash, key)) != null &&
1154 (oldValue = e.value) != null) {
1155 V v = remappingFunction.apply(key, oldValue);
1156 if (v != null) {
1157 e.value = v;
1158 afterNodeAccess(e);
1159 return v;
1160 }
1161 else
1162 removeNode(hash, key, null, false, true);
1163 }
1164 return null;
1165 }
1166
1167 @Override
1168 public V compute(K key,
1169 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1170 if (remappingFunction == null)
1171 throw new NullPointerException();
1172 int hash = hash(key);
1173 Node<K,V>[] tab; Node<K,V> first; int n, i;
1174 int binCount = 0;
1175 TreeNode<K,V> t = null;
1176 Node<K,V> old = null;
1177 if (size > threshold || (tab = table) == null ||
1178 (n = tab.length) == 0)
1179 n = (tab = resize()).length;
1180 if ((first = tab[i = (n - 1) & hash]) != null) {
1181 if (first instanceof TreeNode)
1182 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1183 else {
1184 Node<K,V> e = first; K k;
1185 do {
1186 if (e.hash == hash &&
1187 ((k = e.key) == key || (key != null && key.equals(k)))) {
1188 old = e;
1189 break;
1190 }
1191 ++binCount;
1192 } while ((e = e.next) != null);
1193 }
1194 }
1195 V oldValue = (old == null) ? null : old.value;
1196 V v = remappingFunction.apply(key, oldValue);
1197 if (old != null) {
1198 if (v != null) {
1199 old.value = v;
1200 afterNodeAccess(old);
1201 }
1202 else
1203 removeNode(hash, key, null, false, true);
1204 }
1205 else if (v != null) {
1206 if (t != null)
1207 t.putTreeVal(this, tab, hash, key, v);
1208 else {
1209 tab[i] = newNode(hash, key, v, first);
1210 if (binCount >= TREEIFY_THRESHOLD - 1)
1211 treeifyBin(tab, hash);
1212 }
1213 ++modCount;
1214 ++size;
1215 afterNodeInsertion(true);
1216 }
1217 return v;
1218 }
1219
1220 @Override
1221 public V merge(K key, V value,
1222 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1223 if (value == null)
1224 throw new NullPointerException();
1225 if (remappingFunction == null)
1226 throw new NullPointerException();
1227 int hash = hash(key);
1228 Node<K,V>[] tab; Node<K,V> first; int n, i;
1229 int binCount = 0;
1230 TreeNode<K,V> t = null;
1231 Node<K,V> old = null;
1232 if (size > threshold || (tab = table) == null ||
1233 (n = tab.length) == 0)
1234 n = (tab = resize()).length;
1235 if ((first = tab[i = (n - 1) & hash]) != null) {
1236 if (first instanceof TreeNode)
1237 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1238 else {
1239 Node<K,V> e = first; K k;
1240 do {
1241 if (e.hash == hash &&
1242 ((k = e.key) == key || (key != null && key.equals(k)))) {
1243 old = e;
1244 break;
1245 }
1246 ++binCount;
1247 } while ((e = e.next) != null);
1248 }
1249 }
1250 if (old != null) {
1251 V v;
1252 if (old.value != null)
1253 v = remappingFunction.apply(old.value, value);
1254 else
1255 v = value;
1256 if (v != null) {
1257 old.value = v;
1258 afterNodeAccess(old);
1259 }
1260 else
1261 removeNode(hash, key, null, false, true);
1262 return v;
1263 }
1264 if (value != null) {
1265 if (t != null)
1266 t.putTreeVal(this, tab, hash, key, value);
1267 else {
1268 tab[i] = newNode(hash, key, value, first);
1269 if (binCount >= TREEIFY_THRESHOLD - 1)
1270 treeifyBin(tab, hash);
1271 }
1272 ++modCount;
1273 ++size;
1274 afterNodeInsertion(true);
1275 }
1276 return value;
1277 }
1278
1279 @Override
1280 public void forEach(BiConsumer<? super K, ? super V> action) {
1281 Node<K,V>[] tab;
1282 if (action == null)
1283 throw new NullPointerException();
1284 if (size > 0 && (tab = table) != null) {
1285 int mc = modCount;
1286 for (int i = 0; i < tab.length; ++i) {
1287 for (Node<K,V> e = tab[i]; e != null; e = e.next)
1288 action.accept(e.key, e.value);
1289 }
1290 if (modCount != mc)
1291 throw new ConcurrentModificationException();
1292 }
1293 }
1294
1295 @Override
1296 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1297 Node<K,V>[] tab;
1298 if (function == null)
1299 throw new NullPointerException();
1300 if (size > 0 && (tab = table) != null) {
1301 int mc = modCount;
1302 for (int i = 0; i < tab.length; ++i) {
1303 for (Node<K,V> e = tab[i]; e != null; e = e.next) {
1304 e.value = function.apply(e.key, e.value);
1305 }
1306 }
1307 if (modCount != mc)
1308 throw new ConcurrentModificationException();
1309 }
1310 }
1311
1312 /* ------------------------------------------------------------ */
1313 // Cloning and serialization
1314
1315 /**
1316 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
1317 * values themselves are not cloned.
1318 *
1319 * @return a shallow copy of this map
1320 */
1321 @SuppressWarnings("unchecked")
1322 @Override
1323 public Object clone() {
1324 HashMap<K,V> result;
1325 try {
1326 result = (HashMap<K,V>)super.clone();
1327 } catch (CloneNotSupportedException e) {
1328 // this shouldn't happen, since we are Cloneable
1329 throw new InternalError(e);
1330 }
1331 result.reinitialize();
1332 result.putMapEntries(this, false);
1333 return result;
1334 }
1335
1336 // These methods are also used when serializing HashSets
1337 final float loadFactor() { return loadFactor; }
1338 final int capacity() {
1339 return (table != null) ? table.length :
1340 (threshold > 0) ? threshold :
1341 DEFAULT_INITIAL_CAPACITY;
1342 }
1343
1344 /**
1345 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
1346 * serialize it).
1347 *
1348 * @serialData The <i>capacity</i> of the HashMap (the length of the
1349 * bucket array) is emitted (int), followed by the
1350 * <i>size</i> (an int, the number of key-value
1351 * mappings), followed by the key (Object) and value (Object)
1352 * for each key-value mapping. The key-value mappings are
1353 * emitted in no particular order.
1354 */
1355 private void writeObject(java.io.ObjectOutputStream s)
1356 throws IOException {
1357 int buckets = capacity();
1358 // Write out the threshold, loadfactor, and any hidden stuff
1359 s.defaultWriteObject();
1360 s.writeInt(buckets);
1361 s.writeInt(size);
1362 internalWriteEntries(s);
1363 }
1364
1365 /**
1366 * Reconstitute the {@code HashMap} instance from a stream (i.e.,
1367 * deserialize it).
1368 */
1369 private void readObject(java.io.ObjectInputStream s)
1370 throws IOException, ClassNotFoundException {
1371 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1372 s.defaultReadObject();
1373 reinitialize();
1374 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1375 throw new InvalidObjectException("Illegal load factor: " +
1376 loadFactor);
1377 s.readInt(); // Read and ignore number of buckets
1378 int mappings = s.readInt(); // Read number of mappings (size)
1379 if (mappings < 0)
1380 throw new InvalidObjectException("Illegal mappings count: " +
1381 mappings);
1382 else if (mappings > 0) { // (if zero, use defaults)
1383 // Size the table using given load factor only if within
1384 // range of 0.25...4.0
1385 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1386 float fc = (float)mappings / lf + 1.0f;
1387 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1388 DEFAULT_INITIAL_CAPACITY :
1389 (fc >= MAXIMUM_CAPACITY) ?
1390 MAXIMUM_CAPACITY :
1391 tableSizeFor((int)fc));
1392 float ft = (float)cap * lf;
1393 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1394 (int)ft : Integer.MAX_VALUE);
1395 @SuppressWarnings({"rawtypes","unchecked"})
1396 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1397 table = tab;
1398
1399 // Read the keys and values, and put the mappings in the HashMap
1400 for (int i = 0; i < mappings; i++) {
1401 @SuppressWarnings("unchecked")
1402 K key = (K) s.readObject();
1403 @SuppressWarnings("unchecked")
1404 V value = (V) s.readObject();
1405 putVal(hash(key), key, value, false, false);
1406 }
1407 }
1408 }
1409
1410 /* ------------------------------------------------------------ */
1411 // iterators
1412
1413 abstract class HashIterator {
1414 Node<K,V> next; // next entry to return
1415 Node<K,V> current; // current entry
1416 int expectedModCount; // for fast-fail
1417 int index; // current slot
1418
1419 HashIterator() {
1420 expectedModCount = modCount;
1421 Node<K,V>[] t = table;
1422 current = next = null;
1423 index = 0;
1424 if (t != null && size > 0) { // advance to first entry
1425 do {} while (index < t.length && (next = t[index++]) == null);
1426 }
1427 }
1428
1429 public final boolean hasNext() {
1430 return next != null;
1431 }
1432
1433 final Node<K,V> nextNode() {
1434 Node<K,V>[] t;
1435 Node<K,V> e = next;
1436 if (modCount != expectedModCount)
1437 throw new ConcurrentModificationException();
1438 if (e == null)
1439 throw new NoSuchElementException();
1440 if ((next = (current = e).next) == null && (t = table) != null) {
1441 do {} while (index < t.length && (next = t[index++]) == null);
1442 }
1443 return e;
1444 }
1445
1446 public final void remove() {
1447 Node<K,V> p = current;
1448 if (p == null)
1449 throw new IllegalStateException();
1450 if (modCount != expectedModCount)
1451 throw new ConcurrentModificationException();
1452 current = null;
1453 K key = p.key;
1454 removeNode(hash(key), key, null, false, false);
1455 expectedModCount = modCount;
1456 }
1457 }
1458
1459 final class KeyIterator extends HashIterator
1460 implements Iterator<K> {
1461 public final K next() { return nextNode().key; }
1462 }
1463
1464 final class ValueIterator extends HashIterator
1465 implements Iterator<V> {
1466 public final V next() { return nextNode().value; }
1467 }
1468
1469 final class EntryIterator extends HashIterator
1470 implements Iterator<Map.Entry<K,V>> {
1471 public final Map.Entry<K,V> next() { return nextNode(); }
1472 }
1473
1474 /* ------------------------------------------------------------ */
1475 // spliterators
1476
1477 static class HashMapSpliterator<K,V> {
1478 final HashMap<K,V> map;
1479 Node<K,V> current; // current node
1480 int index; // current index, modified on advance/split
1481 int fence; // one past last index
1482 int est; // size estimate
1483 int expectedModCount; // for comodification checks
1484
1485 HashMapSpliterator(HashMap<K,V> m, int origin,
1486 int fence, int est,
1487 int expectedModCount) {
1488 this.map = m;
1489 this.index = origin;
1490 this.fence = fence;
1491 this.est = est;
1492 this.expectedModCount = expectedModCount;
1493 }
1494
1495 final int getFence() { // initialize fence and size on first use
1496 int hi;
1497 if ((hi = fence) < 0) {
1498 HashMap<K,V> m = map;
1499 est = m.size;
1500 expectedModCount = m.modCount;
1501 Node<K,V>[] tab = m.table;
1502 hi = fence = (tab == null) ? 0 : tab.length;
1503 }
1504 return hi;
1505 }
1506
1507 public final long estimateSize() {
1508 getFence(); // force init
1509 return (long) est;
1510 }
1511 }
1512
1513 static final class KeySpliterator<K,V>
1514 extends HashMapSpliterator<K,V>
1515 implements Spliterator<K> {
1516 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1517 int expectedModCount) {
1518 super(m, origin, fence, est, expectedModCount);
1519 }
1520
1521 public KeySpliterator<K,V> trySplit() {
1522 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1523 return (lo >= mid || current != null) ? null :
1524 new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1525 expectedModCount);
1526 }
1527
1528 public void forEachRemaining(Consumer<? super K> action) {
1529 int i, hi, mc;
1530 if (action == null)
1531 throw new NullPointerException();
1532 HashMap<K,V> m = map;
1533 Node<K,V>[] tab = m.table;
1534 if ((hi = fence) < 0) {
1535 mc = expectedModCount = m.modCount;
1536 hi = fence = (tab == null) ? 0 : tab.length;
1537 }
1538 else
1539 mc = expectedModCount;
1540 if (tab != null && tab.length >= hi &&
1541 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1542 Node<K,V> p = current;
1543 current = null;
1544 do {
1545 if (p == null)
1546 p = tab[i++];
1547 else {
1548 action.accept(p.key);
1549 p = p.next;
1550 }
1551 } while (p != null || i < hi);
1552 if (m.modCount != mc)
1553 throw new ConcurrentModificationException();
1554 }
1555 }
1556
1557 public boolean tryAdvance(Consumer<? super K> action) {
1558 int hi;
1559 if (action == null)
1560 throw new NullPointerException();
1561 Node<K,V>[] tab = map.table;
1562 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1563 while (current != null || index < hi) {
1564 if (current == null)
1565 current = tab[index++];
1566 else {
1567 K k = current.key;
1568 current = current.next;
1569 action.accept(k);
1570 if (map.modCount != expectedModCount)
1571 throw new ConcurrentModificationException();
1572 return true;
1573 }
1574 }
1575 }
1576 return false;
1577 }
1578
1579 public int characteristics() {
1580 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1581 Spliterator.DISTINCT;
1582 }
1583 }
1584
1585 static final class ValueSpliterator<K,V>
1586 extends HashMapSpliterator<K,V>
1587 implements Spliterator<V> {
1588 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1589 int expectedModCount) {
1590 super(m, origin, fence, est, expectedModCount);
1591 }
1592
1593 public ValueSpliterator<K,V> trySplit() {
1594 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1595 return (lo >= mid || current != null) ? null :
1596 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1597 expectedModCount);
1598 }
1599
1600 public void forEachRemaining(Consumer<? super V> action) {
1601 int i, hi, mc;
1602 if (action == null)
1603 throw new NullPointerException();
1604 HashMap<K,V> m = map;
1605 Node<K,V>[] tab = m.table;
1606 if ((hi = fence) < 0) {
1607 mc = expectedModCount = m.modCount;
1608 hi = fence = (tab == null) ? 0 : tab.length;
1609 }
1610 else
1611 mc = expectedModCount;
1612 if (tab != null && tab.length >= hi &&
1613 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1614 Node<K,V> p = current;
1615 current = null;
1616 do {
1617 if (p == null)
1618 p = tab[i++];
1619 else {
1620 action.accept(p.value);
1621 p = p.next;
1622 }
1623 } while (p != null || i < hi);
1624 if (m.modCount != mc)
1625 throw new ConcurrentModificationException();
1626 }
1627 }
1628
1629 public boolean tryAdvance(Consumer<? super V> action) {
1630 int hi;
1631 if (action == null)
1632 throw new NullPointerException();
1633 Node<K,V>[] tab = map.table;
1634 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1635 while (current != null || index < hi) {
1636 if (current == null)
1637 current = tab[index++];
1638 else {
1639 V v = current.value;
1640 current = current.next;
1641 action.accept(v);
1642 if (map.modCount != expectedModCount)
1643 throw new ConcurrentModificationException();
1644 return true;
1645 }
1646 }
1647 }
1648 return false;
1649 }
1650
1651 public int characteristics() {
1652 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1653 }
1654 }
1655
1656 static final class EntrySpliterator<K,V>
1657 extends HashMapSpliterator<K,V>
1658 implements Spliterator<Map.Entry<K,V>> {
1659 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1660 int expectedModCount) {
1661 super(m, origin, fence, est, expectedModCount);
1662 }
1663
1664 public EntrySpliterator<K,V> trySplit() {
1665 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1666 return (lo >= mid || current != null) ? null :
1667 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1668 expectedModCount);
1669 }
1670
1671 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1672 int i, hi, mc;
1673 if (action == null)
1674 throw new NullPointerException();
1675 HashMap<K,V> m = map;
1676 Node<K,V>[] tab = m.table;
1677 if ((hi = fence) < 0) {
1678 mc = expectedModCount = m.modCount;
1679 hi = fence = (tab == null) ? 0 : tab.length;
1680 }
1681 else
1682 mc = expectedModCount;
1683 if (tab != null && tab.length >= hi &&
1684 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1685 Node<K,V> p = current;
1686 current = null;
1687 do {
1688 if (p == null)
1689 p = tab[i++];
1690 else {
1691 action.accept(p);
1692 p = p.next;
1693 }
1694 } while (p != null || i < hi);
1695 if (m.modCount != mc)
1696 throw new ConcurrentModificationException();
1697 }
1698 }
1699
1700 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1701 int hi;
1702 if (action == null)
1703 throw new NullPointerException();
1704 Node<K,V>[] tab = map.table;
1705 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1706 while (current != null || index < hi) {
1707 if (current == null)
1708 current = tab[index++];
1709 else {
1710 Node<K,V> e = current;
1711 current = current.next;
1712 action.accept(e);
1713 if (map.modCount != expectedModCount)
1714 throw new ConcurrentModificationException();
1715 return true;
1716 }
1717 }
1718 }
1719 return false;
1720 }
1721
1722 public int characteristics() {
1723 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1724 Spliterator.DISTINCT;
1725 }
1726 }
1727
1728 /* ------------------------------------------------------------ */
1729 // LinkedHashMap support
1730
1731
1732 /*
1733 * The following package-protected methods are designed to be
1734 * overridden by LinkedHashMap, but not by any other subclass.
1735 * Nearly all other internal methods are also package-protected
1736 * but are declared final, so can be used by LinkedHashMap, view
1737 * classes, and HashSet.
1738 */
1739
1740 // Create a regular (non-tree) node
1741 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1742 return new Node<>(hash, key, value, next);
1743 }
1744
1745 // For conversion from TreeNodes to plain nodes
1746 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1747 return new Node<>(p.hash, p.key, p.value, next);
1748 }
1749
1750 // Create a tree bin node
1751 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1752 return new TreeNode<>(hash, key, value, next);
1753 }
1754
1755 // For treeifyBin
1756 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1757 return new TreeNode<>(p.hash, p.key, p.value, next);
1758 }
1759
1760 /**
1761 * Reset to initial default state. Called by clone and readObject.
1762 */
1763 void reinitialize() {
1764 table = null;
1765 entrySet = null;
1766 keySet = null;
1767 values = null;
1768 modCount = 0;
1769 threshold = 0;
1770 size = 0;
1771 }
1772
1773 // Callbacks to allow LinkedHashMap post-actions
1774 void afterNodeAccess(Node<K,V> p) { }
1775 void afterNodeInsertion(boolean evict) { }
1776 void afterNodeRemoval(Node<K,V> p) { }
1777
1778 // Called only from writeObject, to ensure compatible ordering.
1779 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1780 Node<K,V>[] tab;
1781 if (size > 0 && (tab = table) != null) {
1782 for (int i = 0; i < tab.length; ++i) {
1783 for (Node<K,V> e = tab[i]; e != null; e = e.next) {
1784 s.writeObject(e.key);
1785 s.writeObject(e.value);
1786 }
1787 }
1788 }
1789 }
1790
1791 /* ------------------------------------------------------------ */
1792 // Tree bins
1793
1794 /**
1795 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1796 * extends Node) so can be used as extension of either regular or
1797 * linked node.
1798 */
1799 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1800 TreeNode<K,V> parent; // red-black tree links
1801 TreeNode<K,V> left;
1802 TreeNode<K,V> right;
1803 TreeNode<K,V> prev; // needed to unlink next upon deletion
1804 boolean red;
1805 TreeNode(int hash, K key, V val, Node<K,V> next) {
1806 super(hash, key, val, next);
1807 }
1808
1809 /**
1810 * Returns root of tree containing this node.
1811 */
1812 final TreeNode<K,V> root() {
1813 for (TreeNode<K,V> r = this, p;;) {
1814 if ((p = r.parent) == null)
1815 return r;
1816 r = p;
1817 }
1818 }
1819
1820 /**
1821 * Ensures that the given root is the first node of its bin.
1822 */
1823 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1824 int n;
1825 if (root != null && tab != null && (n = tab.length) > 0) {
1826 int index = (n - 1) & root.hash;
1827 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1828 if (root != first) {
1829 Node<K,V> rn;
1830 tab[index] = root;
1831 TreeNode<K,V> rp = root.prev;
1832 if ((rn = root.next) != null)
1833 ((TreeNode<K,V>)rn).prev = rp;
1834 if (rp != null)
1835 rp.next = rn;
1836 if (first != null)
1837 first.prev = root;
1838 root.next = first;
1839 root.prev = null;
1840 }
1841 assert checkInvariants(root);
1842 }
1843 }
1844
1845 /**
1846 * Finds the node starting at root p with the given hash and key.
1847 * The kc argument caches comparableClassFor(key) upon first use
1848 * comparing keys.
1849 */
1850 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1851 TreeNode<K,V> p = this;
1852 do {
1853 int ph, dir; K pk;
1854 TreeNode<K,V> pl = p.left, pr = p.right, q;
1855 if ((ph = p.hash) > h)
1856 p = pl;
1857 else if (ph < h)
1858 p = pr;
1859 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1860 return p;
1861 else if (pl == null)
1862 p = pr;
1863 else if (pr == null)
1864 p = pl;
1865 else if ((kc != null ||
1866 (kc = comparableClassFor(k)) != null) &&
1867 (dir = compareComparables(kc, k, pk)) != 0)
1868 p = (dir < 0) ? pl : pr;
1869 else if ((q = pr.find(h, k, kc)) != null)
1870 return q;
1871 else
1872 p = pl;
1873 } while (p != null);
1874 return null;
1875 }
1876
1877 /**
1878 * Calls find for root node.
1879 */
1880 final TreeNode<K,V> getTreeNode(int h, Object k) {
1881 return ((parent != null) ? root() : this).find(h, k, null);
1882 }
1883
1884 /**
1885 * Tie-breaking utility for ordering insertions when equal
1886 * hashCodes and non-comparable. We don't require a total
1887 * order, just a consistent insertion rule to maintain
1888 * equivalence across rebalancings. Tie-breaking further than
1889 * necessary simplifies testing a bit.
1890 */
1891 static int tieBreakOrder(Object a, Object b) {
1892 int d;
1893 if (a == null || b == null ||
1894 (d = a.getClass().getName().
1895 compareTo(b.getClass().getName())) == 0)
1896 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1897 -1 : 1);
1898 return d;
1899 }
1900
1901 /**
1902 * Forms tree of the nodes linked from this node.
1903 * @return root of tree
1904 */
1905 final void treeify(Node<K,V>[] tab) {
1906 TreeNode<K,V> root = null;
1907 for (TreeNode<K,V> x = this, next; x != null; x = next) {
1908 next = (TreeNode<K,V>)x.next;
1909 x.left = x.right = null;
1910 if (root == null) {
1911 x.parent = null;
1912 x.red = false;
1913 root = x;
1914 }
1915 else {
1916 K k = x.key;
1917 int h = x.hash;
1918 Class<?> kc = null;
1919 for (TreeNode<K,V> p = root;;) {
1920 int dir, ph;
1921 K pk = p.key;
1922 if ((ph = p.hash) > h)
1923 dir = -1;
1924 else if (ph < h)
1925 dir = 1;
1926 else if ((kc == null &&
1927 (kc = comparableClassFor(k)) == null) ||
1928 (dir = compareComparables(kc, k, pk)) == 0)
1929 dir = tieBreakOrder(k, pk);
1930
1931 TreeNode<K,V> xp = p;
1932 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1933 x.parent = xp;
1934 if (dir <= 0)
1935 xp.left = x;
1936 else
1937 xp.right = x;
1938 root = balanceInsertion(root, x);
1939 break;
1940 }
1941 }
1942 }
1943 }
1944 moveRootToFront(tab, root);
1945 }
1946
1947 /**
1948 * Returns a list of non-TreeNodes replacing those linked from
1949 * this node.
1950 */
1951 final Node<K,V> untreeify(HashMap<K,V> map) {
1952 Node<K,V> hd = null, tl = null;
1953 for (Node<K,V> q = this; q != null; q = q.next) {
1954 Node<K,V> p = map.replacementNode(q, null);
1955 if (tl == null)
1956 hd = p;
1957 else
1958 tl.next = p;
1959 tl = p;
1960 }
1961 return hd;
1962 }
1963
1964 /**
1965 * Tree version of putVal.
1966 */
1967 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
1968 int h, K k, V v) {
1969 Class<?> kc = null;
1970 boolean searched = false;
1971 TreeNode<K,V> root = (parent != null) ? root() : this;
1972 for (TreeNode<K,V> p = root;;) {
1973 int dir, ph; K pk;
1974 if ((ph = p.hash) > h)
1975 dir = -1;
1976 else if (ph < h)
1977 dir = 1;
1978 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1979 return p;
1980 else if ((kc == null &&
1981 (kc = comparableClassFor(k)) == null) ||
1982 (dir = compareComparables(kc, k, pk)) == 0) {
1983 if (!searched) {
1984 TreeNode<K,V> q, ch;
1985 searched = true;
1986 if (((ch = p.left) != null &&
1987 (q = ch.find(h, k, kc)) != null) ||
1988 ((ch = p.right) != null &&
1989 (q = ch.find(h, k, kc)) != null))
1990 return q;
1991 }
1992 dir = tieBreakOrder(k, pk);
1993 }
1994
1995 TreeNode<K,V> xp = p;
1996 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1997 Node<K,V> xpn = xp.next;
1998 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
1999 if (dir <= 0)
2000 xp.left = x;
2001 else
2002 xp.right = x;
2003 xp.next = x;
2004 x.parent = x.prev = xp;
2005 if (xpn != null)
2006 ((TreeNode<K,V>)xpn).prev = x;
2007 moveRootToFront(tab, balanceInsertion(root, x));
2008 return null;
2009 }
2010 }
2011 }
2012
2013 /**
2014 * Removes the given node, that must be present before this call.
2015 * This is messier than typical red-black deletion code because we
2016 * cannot swap the contents of an interior node with a leaf
2017 * successor that is pinned by "next" pointers that are accessible
2018 * independently during traversal. So instead we swap the tree
2019 * linkages. If the current tree appears to have too few nodes,
2020 * the bin is converted back to a plain bin. (The test triggers
2021 * somewhere between 2 and 6 nodes, depending on tree structure).
2022 */
2023 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2024 boolean movable) {
2025 int n;
2026 if (tab == null || (n = tab.length) == 0)
2027 return;
2028 int index = (n - 1) & hash;
2029 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2030 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2031 if (pred == null)
2032 tab[index] = first = succ;
2033 else
2034 pred.next = succ;
2035 if (succ != null)
2036 succ.prev = pred;
2037 if (first == null)
2038 return;
2039 if (root.parent != null)
2040 root = root.root();
2041 if (root == null || root.right == null ||
2042 (rl = root.left) == null || rl.left == null) {
2043 tab[index] = first.untreeify(map); // too small
2044 return;
2045 }
2046 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2047 if (pl != null && pr != null) {
2048 TreeNode<K,V> s = pr, sl;
2049 while ((sl = s.left) != null) // find successor
2050 s = sl;
2051 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2052 TreeNode<K,V> sr = s.right;
2053 TreeNode<K,V> pp = p.parent;
2054 if (s == pr) { // p was s's direct parent
2055 p.parent = s;
2056 s.right = p;
2057 }
2058 else {
2059 TreeNode<K,V> sp = s.parent;
2060 if ((p.parent = sp) != null) {
2061 if (s == sp.left)
2062 sp.left = p;
2063 else
2064 sp.right = p;
2065 }
2066 if ((s.right = pr) != null)
2067 pr.parent = s;
2068 }
2069 p.left = null;
2070 if ((p.right = sr) != null)
2071 sr.parent = p;
2072 if ((s.left = pl) != null)
2073 pl.parent = s;
2074 if ((s.parent = pp) == null)
2075 root = s;
2076 else if (p == pp.left)
2077 pp.left = s;
2078 else
2079 pp.right = s;
2080 if (sr != null)
2081 replacement = sr;
2082 else
2083 replacement = p;
2084 }
2085 else if (pl != null)
2086 replacement = pl;
2087 else if (pr != null)
2088 replacement = pr;
2089 else
2090 replacement = p;
2091 if (replacement != p) {
2092 TreeNode<K,V> pp = replacement.parent = p.parent;
2093 if (pp == null)
2094 root = replacement;
2095 else if (p == pp.left)
2096 pp.left = replacement;
2097 else
2098 pp.right = replacement;
2099 p.left = p.right = p.parent = null;
2100 }
2101
2102 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2103
2104 if (replacement == p) { // detach
2105 TreeNode<K,V> pp = p.parent;
2106 p.parent = null;
2107 if (pp != null) {
2108 if (p == pp.left)
2109 pp.left = null;
2110 else if (p == pp.right)
2111 pp.right = null;
2112 }
2113 }
2114 if (movable)
2115 moveRootToFront(tab, r);
2116 }
2117
2118 /**
2119 * Splits nodes in a tree bin into lower and upper tree bins,
2120 * or untreeifies if now too small. Called only from resize;
2121 * see above discussion about split bits and indices.
2122 *
2123 * @param map the map
2124 * @param tab the table for recording bin heads
2125 * @param index the index of the table being split
2126 * @param bit the bit of hash to split on
2127 */
2128 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2129 TreeNode<K,V> b = this;
2130 // Relink into lo and hi lists, preserving order
2131 TreeNode<K,V> loHead = null, loTail = null;
2132 TreeNode<K,V> hiHead = null, hiTail = null;
2133 int lc = 0, hc = 0;
2134 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2135 next = (TreeNode<K,V>)e.next;
2136 e.next = null;
2137 if ((e.hash & bit) == 0) {
2138 if ((e.prev = loTail) == null)
2139 loHead = e;
2140 else
2141 loTail.next = e;
2142 loTail = e;
2143 ++lc;
2144 }
2145 else {
2146 if ((e.prev = hiTail) == null)
2147 hiHead = e;
2148 else
2149 hiTail.next = e;
2150 hiTail = e;
2151 ++hc;
2152 }
2153 }
2154
2155 if (loHead != null) {
2156 if (lc <= UNTREEIFY_THRESHOLD)
2157 tab[index] = loHead.untreeify(map);
2158 else {
2159 tab[index] = loHead;
2160 if (hiHead != null) // (else is already treeified)
2161 loHead.treeify(tab);
2162 }
2163 }
2164 if (hiHead != null) {
2165 if (hc <= UNTREEIFY_THRESHOLD)
2166 tab[index + bit] = hiHead.untreeify(map);
2167 else {
2168 tab[index + bit] = hiHead;
2169 if (loHead != null)
2170 hiHead.treeify(tab);
2171 }
2172 }
2173 }
2174
2175 /* ------------------------------------------------------------ */
2176 // Red-black tree methods, all adapted from CLR
2177
2178 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2179 TreeNode<K,V> p) {
2180 TreeNode<K,V> r, pp, rl;
2181 if (p != null && (r = p.right) != null) {
2182 if ((rl = p.right = r.left) != null)
2183 rl.parent = p;
2184 if ((pp = r.parent = p.parent) == null)
2185 (root = r).red = false;
2186 else if (pp.left == p)
2187 pp.left = r;
2188 else
2189 pp.right = r;
2190 r.left = p;
2191 p.parent = r;
2192 }
2193 return root;
2194 }
2195
2196 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2197 TreeNode<K,V> p) {
2198 TreeNode<K,V> l, pp, lr;
2199 if (p != null && (l = p.left) != null) {
2200 if ((lr = p.left = l.right) != null)
2201 lr.parent = p;
2202 if ((pp = l.parent = p.parent) == null)
2203 (root = l).red = false;
2204 else if (pp.right == p)
2205 pp.right = l;
2206 else
2207 pp.left = l;
2208 l.right = p;
2209 p.parent = l;
2210 }
2211 return root;
2212 }
2213
2214 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2215 TreeNode<K,V> x) {
2216 x.red = true;
2217 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2218 if ((xp = x.parent) == null) {
2219 x.red = false;
2220 return x;
2221 }
2222 else if (!xp.red || (xpp = xp.parent) == null)
2223 return root;
2224 if (xp == (xppl = xpp.left)) {
2225 if ((xppr = xpp.right) != null && xppr.red) {
2226 xppr.red = false;
2227 xp.red = false;
2228 xpp.red = true;
2229 x = xpp;
2230 }
2231 else {
2232 if (x == xp.right) {
2233 root = rotateLeft(root, x = xp);
2234 xpp = (xp = x.parent) == null ? null : xp.parent;
2235 }
2236 if (xp != null) {
2237 xp.red = false;
2238 if (xpp != null) {
2239 xpp.red = true;
2240 root = rotateRight(root, xpp);
2241 }
2242 }
2243 }
2244 }
2245 else {
2246 if (xppl != null && xppl.red) {
2247 xppl.red = false;
2248 xp.red = false;
2249 xpp.red = true;
2250 x = xpp;
2251 }
2252 else {
2253 if (x == xp.left) {
2254 root = rotateRight(root, x = xp);
2255 xpp = (xp = x.parent) == null ? null : xp.parent;
2256 }
2257 if (xp != null) {
2258 xp.red = false;
2259 if (xpp != null) {
2260 xpp.red = true;
2261 root = rotateLeft(root, xpp);
2262 }
2263 }
2264 }
2265 }
2266 }
2267 }
2268
2269 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2270 TreeNode<K,V> x) {
2271 for (TreeNode<K,V> xp, xpl, xpr;;) {
2272 if (x == null || x == root)
2273 return root;
2274 else if ((xp = x.parent) == null) {
2275 x.red = false;
2276 return x;
2277 }
2278 else if (x.red) {
2279 x.red = false;
2280 return root;
2281 }
2282 else if ((xpl = xp.left) == x) {
2283 if ((xpr = xp.right) != null && xpr.red) {
2284 xpr.red = false;
2285 xp.red = true;
2286 root = rotateLeft(root, xp);
2287 xpr = (xp = x.parent) == null ? null : xp.right;
2288 }
2289 if (xpr == null)
2290 x = xp;
2291 else {
2292 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2293 if ((sr == null || !sr.red) &&
2294 (sl == null || !sl.red)) {
2295 xpr.red = true;
2296 x = xp;
2297 }
2298 else {
2299 if (sr == null || !sr.red) {
2300 if (sl != null)
2301 sl.red = false;
2302 xpr.red = true;
2303 root = rotateRight(root, xpr);
2304 xpr = (xp = x.parent) == null ?
2305 null : xp.right;
2306 }
2307 if (xpr != null) {
2308 xpr.red = (xp == null) ? false : xp.red;
2309 if ((sr = xpr.right) != null)
2310 sr.red = false;
2311 }
2312 if (xp != null) {
2313 xp.red = false;
2314 root = rotateLeft(root, xp);
2315 }
2316 x = root;
2317 }
2318 }
2319 }
2320 else { // symmetric
2321 if (xpl != null && xpl.red) {
2322 xpl.red = false;
2323 xp.red = true;
2324 root = rotateRight(root, xp);
2325 xpl = (xp = x.parent) == null ? null : xp.left;
2326 }
2327 if (xpl == null)
2328 x = xp;
2329 else {
2330 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2331 if ((sl == null || !sl.red) &&
2332 (sr == null || !sr.red)) {
2333 xpl.red = true;
2334 x = xp;
2335 }
2336 else {
2337 if (sl == null || !sl.red) {
2338 if (sr != null)
2339 sr.red = false;
2340 xpl.red = true;
2341 root = rotateLeft(root, xpl);
2342 xpl = (xp = x.parent) == null ?
2343 null : xp.left;
2344 }
2345 if (xpl != null) {
2346 xpl.red = (xp == null) ? false : xp.red;
2347 if ((sl = xpl.left) != null)
2348 sl.red = false;
2349 }
2350 if (xp != null) {
2351 xp.red = false;
2352 root = rotateRight(root, xp);
2353 }
2354 x = root;
2355 }
2356 }
2357 }
2358 }
2359 }
2360
2361 /**
2362 * Recursive invariant check
2363 */
2364 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2365 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2366 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2367 if (tb != null && tb.next != t)
2368 return false;
2369 if (tn != null && tn.prev != t)
2370 return false;
2371 if (tp != null && t != tp.left && t != tp.right)
2372 return false;
2373 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2374 return false;
2375 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2376 return false;
2377 if (t.red && tl != null && tl.red && tr != null && tr.red)
2378 return false;
2379 if (tl != null && !checkInvariants(tl))
2380 return false;
2381 if (tr != null && !checkInvariants(tr))
2382 return false;
2383 return true;
2384 }
2385 }
2386
2387 }