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;
906 return (ks = keySet) == null ? (keySet = new KeySet()) : ks;
907 }
908
909 final class KeySet extends AbstractSet<K> {
910 public final int size() { return size; }
911 public final void clear() { HashMap.this.clear(); }
912 public final Iterator<K> iterator() { return new KeyIterator(); }
913 public final boolean contains(Object o) { return containsKey(o); }
914 public final boolean remove(Object key) {
915 return removeNode(hash(key), key, null, false, true) != null;
916 }
917 public final Spliterator<K> spliterator() {
918 return new KeySpliterator<K,V>(HashMap.this, 0, -1, 0, 0);
919 }
920 public final void forEach(Consumer<? super K> action) {
921 Node<K,V>[] tab;
922 if (action == null)
923 throw new NullPointerException();
924 if (size > 0 && (tab = table) != null) {
925 int mc = modCount;
926 for (int i = 0; i < tab.length; ++i) {
927 for (Node<K,V> e = tab[i]; e != null; e = e.next)
928 action.accept(e.key);
929 }
930 if (modCount != mc)
931 throw new ConcurrentModificationException();
932 }
933 }
934 }
935
936 /**
937 * Returns a {@link Collection} view of the values contained in this map.
938 * The collection is backed by the map, so changes to the map are
939 * reflected in the collection, and vice-versa. If the map is
940 * modified while an iteration over the collection is in progress
941 * (except through the iterator's own <tt>remove</tt> operation),
942 * the results of the iteration are undefined. The collection
943 * supports element removal, which removes the corresponding
944 * mapping from the map, via the <tt>Iterator.remove</tt>,
945 * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
946 * <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
947 * support the <tt>add</tt> or <tt>addAll</tt> operations.
948 *
949 * @return a view of the values contained in this map
950 */
951 public Collection<V> values() {
952 Collection<V> vs;
953 return (vs = values) == null ? (values = new Values()) : vs;
954 }
955
956 final class Values extends AbstractCollection<V> {
957 public final int size() { return size; }
958 public final void clear() { HashMap.this.clear(); }
959 public final Iterator<V> iterator() { return new ValueIterator(); }
960 public final boolean contains(Object o) { return containsValue(o); }
961 public final Spliterator<V> spliterator() {
962 return new ValueSpliterator<K,V>(HashMap.this, 0, -1, 0, 0);
963 }
964 public final void forEach(Consumer<? super V> action) {
965 Node<K,V>[] tab;
966 if (action == null)
967 throw new NullPointerException();
968 if (size > 0 && (tab = table) != null) {
969 int mc = modCount;
970 for (int i = 0; i < tab.length; ++i) {
971 for (Node<K,V> e = tab[i]; e != null; e = e.next)
972 action.accept(e.value);
973 }
974 if (modCount != mc)
975 throw new ConcurrentModificationException();
976 }
977 }
978 }
979
980 /**
981 * Returns a {@link Set} view of the mappings contained in this map.
982 * The set is backed by the map, so changes to the map are
983 * reflected in the set, and vice-versa. If the map is modified
984 * while an iteration over the set is in progress (except through
985 * the iterator's own <tt>remove</tt> operation, or through the
986 * <tt>setValue</tt> operation on a map entry returned by the
987 * iterator) the results of the iteration are undefined. The set
988 * supports element removal, which removes the corresponding
989 * mapping from the map, via the <tt>Iterator.remove</tt>,
990 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
991 * <tt>clear</tt> operations. It does not support the
992 * <tt>add</tt> or <tt>addAll</tt> operations.
993 *
994 * @return a set view of the mappings contained in this map
995 */
996 public Set<Map.Entry<K,V>> entrySet() {
997 Set<Map.Entry<K,V>> es;
998 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
999 }
1000
1001 final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1002 public final int size() { return size; }
1003 public final void clear() { HashMap.this.clear(); }
1004 public final Iterator<Map.Entry<K,V>> iterator() {
1005 return new EntryIterator();
1006 }
1007 public final boolean contains(Object o) {
1008 if (!(o instanceof Map.Entry))
1009 return false;
1010 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1011 Object key = e.getKey();
1012 Node<K,V> candidate = getNode(hash(key), key);
1013 return candidate != null && candidate.equals(e);
1014 }
1015 public final boolean remove(Object o) {
1016 if (o instanceof Map.Entry) {
1017 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1018 Object key = e.getKey();
1019 Object value = e.getValue();
1020 return removeNode(hash(key), key, value, true, true) != null;
1021 }
1022 return false;
1023 }
1024 public final Spliterator<Map.Entry<K,V>> spliterator() {
1025 return new EntrySpliterator<K,V>(HashMap.this, 0, -1, 0, 0);
1026 }
1027 public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1028 Node<K,V>[] tab;
1029 if (action == null)
1030 throw new NullPointerException();
1031 if (size > 0 && (tab = table) != null) {
1032 int mc = modCount;
1033 for (int i = 0; i < tab.length; ++i) {
1034 for (Node<K,V> e = tab[i]; e != null; e = e.next)
1035 action.accept(e);
1036 }
1037 if (modCount != mc)
1038 throw new ConcurrentModificationException();
1039 }
1040 }
1041 }
1042
1043 // Overrides of JDK8 Map extension methods
1044
1045 public V getOrDefault(Object key, V defaultValue) {
1046 Node<K,V> e;
1047 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1048 }
1049
1050 public V putIfAbsent(K key, V value) {
1051 return putVal(hash(key), key, value, true, true);
1052 }
1053
1054 public boolean remove(Object key, Object value) {
1055 return removeNode(hash(key), key, value, true, true) != null;
1056 }
1057
1058 public boolean replace(K key, V oldValue, V newValue) {
1059 Node<K,V> e; V v;
1060 if ((e = getNode(hash(key), key)) != null &&
1061 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1062 e.value = newValue;
1063 afterNodeAccess(e);
1064 return true;
1065 }
1066 return false;
1067 }
1068
1069 public V replace(K key, V value) {
1070 Node<K,V> e;
1071 if ((e = getNode(hash(key), key)) != null) {
1072 V oldValue = e.value;
1073 e.value = value;
1074 afterNodeAccess(e);
1075 return oldValue;
1076 }
1077 return null;
1078 }
1079
1080 public V computeIfAbsent(K key,
1081 Function<? super K, ? extends V> mappingFunction) {
1082 if (mappingFunction == null)
1083 throw new NullPointerException();
1084 int hash = hash(key);
1085 Node<K,V>[] tab; Node<K,V> first; int n, i;
1086 int binCount = 0;
1087 TreeNode<K,V> t = null;
1088 Node<K,V> old = null;
1089 if (size > threshold || (tab = table) == null ||
1090 (n = tab.length) == 0)
1091 n = (tab = resize()).length;
1092 if ((first = tab[i = (n - 1) & hash]) != null) {
1093 if (first instanceof TreeNode)
1094 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1095 else {
1096 Node<K,V> e = first; K k;
1097 do {
1098 if (e.hash == hash &&
1099 ((k = e.key) == key || (key != null && key.equals(k)))) {
1100 old = e;
1101 break;
1102 }
1103 ++binCount;
1104 } while ((e = e.next) != null);
1105 }
1106 V oldValue;
1107 if (old != null && (oldValue = old.value) != null) {
1108 afterNodeAccess(old);
1109 return oldValue;
1110 }
1111 }
1112 V v = mappingFunction.apply(key);
1113 if (old != null) {
1114 old.value = v;
1115 afterNodeAccess(old);
1116 return v;
1117 }
1118 else if (v == null)
1119 return null;
1120 else if (t != null)
1121 t.putTreeVal(this, tab, hash, key, v);
1122 else {
1123 tab[i] = newNode(hash, key, v, first);
1124 if (binCount >= TREEIFY_THRESHOLD - 1)
1125 treeifyBin(tab, hash);
1126 }
1127 ++modCount;
1128 ++size;
1129 afterNodeInsertion(true);
1130 return v;
1131 }
1132
1133 public V computeIfPresent(K key,
1134 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1135 if (remappingFunction == null)
1136 throw new NullPointerException();
1137 Node<K,V> e; V oldValue;
1138 int hash = hash(key);
1139 if ((e = getNode(hash, key)) != null &&
1140 (oldValue = e.value) != null) {
1141 V v = remappingFunction.apply(key, oldValue);
1142 if (v != null) {
1143 e.value = v;
1144 afterNodeAccess(e);
1145 return v;
1146 }
1147 else
1148 removeNode(hash, key, null, false, true);
1149 }
1150 return null;
1151 }
1152
1153 public V compute(K key,
1154 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1155 if (remappingFunction == null)
1156 throw new NullPointerException();
1157 int hash = hash(key);
1158 Node<K,V>[] tab; Node<K,V> first; int n, i;
1159 int binCount = 0;
1160 TreeNode<K,V> t = null;
1161 Node<K,V> old = null;
1162 if (size > threshold || (tab = table) == null ||
1163 (n = tab.length) == 0)
1164 n = (tab = resize()).length;
1165 if ((first = tab[i = (n - 1) & hash]) != null) {
1166 if (first instanceof TreeNode)
1167 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1168 else {
1169 Node<K,V> e = first; K k;
1170 do {
1171 if (e.hash == hash &&
1172 ((k = e.key) == key || (key != null && key.equals(k)))) {
1173 old = e;
1174 break;
1175 }
1176 ++binCount;
1177 } while ((e = e.next) != null);
1178 }
1179 }
1180 V oldValue = (old == null) ? null : old.value;
1181 V v = remappingFunction.apply(key, oldValue);
1182 if (old != null) {
1183 if (v != null) {
1184 old.value = v;
1185 afterNodeAccess(old);
1186 }
1187 else
1188 removeNode(hash, key, null, false, true);
1189 }
1190 else if (v != null) {
1191 if (t != null)
1192 t.putTreeVal(this, tab, hash, key, v);
1193 else {
1194 tab[i] = newNode(hash, key, v, first);
1195 if (binCount >= TREEIFY_THRESHOLD - 1)
1196 treeifyBin(tab, hash);
1197 }
1198 ++modCount;
1199 ++size;
1200 afterNodeInsertion(true);
1201 }
1202 return v;
1203 }
1204
1205 public V merge(K key, V value,
1206 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1207 if (remappingFunction == null)
1208 throw new NullPointerException();
1209 int hash = hash(key);
1210 Node<K,V>[] tab; Node<K,V> first; int n, i;
1211 int binCount = 0;
1212 TreeNode<K,V> t = null;
1213 Node<K,V> old = null;
1214 if (size > threshold || (tab = table) == null ||
1215 (n = tab.length) == 0)
1216 n = (tab = resize()).length;
1217 if ((first = tab[i = (n - 1) & hash]) != null) {
1218 if (first instanceof TreeNode)
1219 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1220 else {
1221 Node<K,V> e = first; K k;
1222 do {
1223 if (e.hash == hash &&
1224 ((k = e.key) == key || (key != null && key.equals(k)))) {
1225 old = e;
1226 break;
1227 }
1228 ++binCount;
1229 } while ((e = e.next) != null);
1230 }
1231 }
1232 if (old != null) {
1233 V v;
1234 if(old.value != null)
1235 v = remappingFunction.apply(old.value, value);
1236 else
1237 v = value;
1238 if (v != null) {
1239 old.value = v;
1240 afterNodeAccess(old);
1241 }
1242 else
1243 removeNode(hash, key, null, false, true);
1244 return v;
1245 }
1246 if (value != null) {
1247 if (t != null)
1248 t.putTreeVal(this, tab, hash, key, value);
1249 else {
1250 tab[i] = newNode(hash, key, value, first);
1251 if (binCount >= TREEIFY_THRESHOLD - 1)
1252 treeifyBin(tab, hash);
1253 }
1254 ++modCount;
1255 ++size;
1256 afterNodeInsertion(true);
1257 }
1258 return value;
1259 }
1260
1261 public void forEach(BiConsumer<? super K, ? super V> action) {
1262 Node<K,V>[] tab;
1263 if (action == null)
1264 throw new NullPointerException();
1265 if (size > 0 && (tab = table) != null) {
1266 int mc = modCount;
1267 for (int i = 0; i < tab.length; ++i) {
1268 for (Node<K,V> e = tab[i]; e != null; e = e.next)
1269 action.accept(e.key, e.value);
1270 }
1271 if (modCount != mc)
1272 throw new ConcurrentModificationException();
1273 }
1274 }
1275
1276 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1277 Node<K,V>[] tab;
1278 if (function == null)
1279 throw new NullPointerException();
1280 if (size > 0 && (tab = table) != null) {
1281 int mc = modCount;
1282 for (int i = 0; i < tab.length; ++i) {
1283 for (Node<K,V> e = tab[i]; e != null; e = e.next) {
1284 e.value = function.apply(e.key, e.value);
1285 }
1286 }
1287 if (modCount != mc)
1288 throw new ConcurrentModificationException();
1289 }
1290 }
1291
1292 /* ------------------------------------------------------------ */
1293 // Cloning and serialization
1294
1295 /**
1296 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
1297 * values themselves are not cloned.
1298 *
1299 * @return a shallow copy of this map
1300 */
1301 @SuppressWarnings("unchecked")
1302 public Object clone() {
1303 HashMap<K,V> result;
1304 try {
1305 result = (HashMap<K,V>)super.clone();
1306 } catch (CloneNotSupportedException e) {
1307 // this shouldn't happen, since we are Cloneable
1308 throw new InternalError(e);
1309 }
1310 result.reinitialize();
1311 result.putMapEntries(this, false);
1312 return result;
1313 }
1314
1315 // These methods are also used when serializing HashSets
1316 final float loadFactor() { return loadFactor; }
1317 final int capacity() {
1318 return (table != null) ? table.length :
1319 (threshold > 0) ? threshold :
1320 DEFAULT_INITIAL_CAPACITY;
1321 }
1322
1323 /**
1324 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
1325 * serialize it).
1326 *
1327 * @serialData The <i>capacity</i> of the HashMap (the length of the
1328 * bucket array) is emitted (int), followed by the
1329 * <i>size</i> (an int, the number of key-value
1330 * mappings), followed by the key (Object) and value (Object)
1331 * for each key-value mapping. The key-value mappings are
1332 * emitted in no particular order.
1333 */
1334 private void writeObject(java.io.ObjectOutputStream s)
1335 throws IOException {
1336 int buckets = capacity();
1337 // Write out the threshold, loadfactor, and any hidden stuff
1338 s.defaultWriteObject();
1339 s.writeInt(buckets);
1340 s.writeInt(size);
1341 internalWriteEntries(s);
1342 }
1343
1344 /**
1345 * Reconstitute the {@code HashMap} instance from a stream (i.e.,
1346 * deserialize it).
1347 */
1348 private void readObject(java.io.ObjectInputStream s)
1349 throws IOException, ClassNotFoundException {
1350 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1351 s.defaultReadObject();
1352 reinitialize();
1353 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1354 throw new InvalidObjectException("Illegal load factor: " +
1355 loadFactor);
1356 s.readInt(); // Read and ignore number of buckets
1357 int mappings = s.readInt(); // Read number of mappings (size)
1358 if (mappings < 0)
1359 throw new InvalidObjectException("Illegal mappings count: " +
1360 mappings);
1361 else if (mappings > 0) { // (if zero, use defaults)
1362 // Size the table using given load factor only if within
1363 // range of 0.25...4.0
1364 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1365 float fc = (float)mappings / lf + 1.0f;
1366 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1367 DEFAULT_INITIAL_CAPACITY :
1368 (fc >= MAXIMUM_CAPACITY) ?
1369 MAXIMUM_CAPACITY :
1370 tableSizeFor((int)fc));
1371 float ft = (float)cap * lf;
1372 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1373 (int)ft : Integer.MAX_VALUE);
1374 @SuppressWarnings({"rawtypes","unchecked"})
1375 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1376 table = tab;
1377
1378 // Read the keys and values, and put the mappings in the HashMap
1379 for (int i = 0; i < mappings; i++) {
1380 @SuppressWarnings("unchecked")
1381 K key = (K) s.readObject();
1382 @SuppressWarnings("unchecked")
1383 V value = (V) s.readObject();
1384 putVal(hash(key), key, value, false, false);
1385 }
1386 }
1387 }
1388
1389 /* ------------------------------------------------------------ */
1390 // iterators
1391
1392 abstract class HashIterator {
1393 Node<K,V> next; // next entry to return
1394 Node<K,V> current; // current entry
1395 int expectedModCount; // for fast-fail
1396 int index; // current slot
1397
1398 HashIterator() {
1399 expectedModCount = modCount;
1400 Node<K,V>[] t = table;
1401 current = next = null;
1402 index = 0;
1403 if (t != null && size > 0) { // advance to first entry
1404 do {} while (index < t.length && (next = t[index++]) == null);
1405 }
1406 }
1407
1408 public final boolean hasNext() {
1409 return next != null;
1410 }
1411
1412 final Node<K,V> nextNode() {
1413 Node<K,V>[] t;
1414 Node<K,V> e = next;
1415 if (modCount != expectedModCount)
1416 throw new ConcurrentModificationException();
1417 if (e == null)
1418 throw new NoSuchElementException();
1419 if ((next = (current = e).next) == null && (t = table) != null) {
1420 do {} while (index < t.length && (next = t[index++]) == null);
1421 }
1422 return e;
1423 }
1424
1425 public final void remove() {
1426 Node<K,V> p = current;
1427 if (p == null)
1428 throw new IllegalStateException();
1429 if (modCount != expectedModCount)
1430 throw new ConcurrentModificationException();
1431 current = null;
1432 K key = p.key;
1433 removeNode(hash(key), key, null, false, false);
1434 expectedModCount = modCount;
1435 }
1436 }
1437
1438 final class KeyIterator extends HashIterator
1439 implements Iterator<K> {
1440 public final K next() { return nextNode().key; }
1441 }
1442
1443 final class ValueIterator extends HashIterator
1444 implements Iterator<V> {
1445 public final V next() { return nextNode().value; }
1446 }
1447
1448 final class EntryIterator extends HashIterator
1449 implements Iterator<Map.Entry<K,V>> {
1450 public final Map.Entry<K,V> next() { return nextNode(); }
1451 }
1452
1453 /* ------------------------------------------------------------ */
1454 // spliterators
1455
1456 static class HashMapSpliterator<K,V> {
1457 final HashMap<K,V> map;
1458 Node<K,V> current; // current node
1459 int index; // current index, modified on advance/split
1460 int fence; // one past last index
1461 int est; // size estimate
1462 int expectedModCount; // for comodification checks
1463
1464 HashMapSpliterator(HashMap<K,V> m, int origin,
1465 int fence, int est,
1466 int expectedModCount) {
1467 this.map = m;
1468 this.index = origin;
1469 this.fence = fence;
1470 this.est = est;
1471 this.expectedModCount = expectedModCount;
1472 }
1473
1474 final int getFence() { // initialize fence and size on first use
1475 int hi;
1476 if ((hi = fence) < 0) {
1477 HashMap<K,V> m = map;
1478 est = m.size;
1479 expectedModCount = m.modCount;
1480 Node<K,V>[] tab = m.table;
1481 hi = fence = (tab == null) ? 0 : tab.length;
1482 }
1483 return hi;
1484 }
1485
1486 public final long estimateSize() {
1487 getFence(); // force init
1488 return (long) est;
1489 }
1490 }
1491
1492 static final class KeySpliterator<K,V>
1493 extends HashMapSpliterator<K,V>
1494 implements Spliterator<K> {
1495 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1496 int expectedModCount) {
1497 super(m, origin, fence, est, expectedModCount);
1498 }
1499
1500 public KeySpliterator<K,V> trySplit() {
1501 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1502 return (lo >= mid || current != null) ? null :
1503 new KeySpliterator<K,V>(map, lo, index = mid, est >>>= 1,
1504 expectedModCount);
1505 }
1506
1507 public void forEachRemaining(Consumer<? super K> action) {
1508 int i, hi, mc;
1509 if (action == null)
1510 throw new NullPointerException();
1511 HashMap<K,V> m = map;
1512 Node<K,V>[] tab = m.table;
1513 if ((hi = fence) < 0) {
1514 mc = expectedModCount = m.modCount;
1515 hi = fence = (tab == null) ? 0 : tab.length;
1516 }
1517 else
1518 mc = expectedModCount;
1519 if (tab != null && tab.length >= hi &&
1520 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1521 Node<K,V> p = current;
1522 current = null;
1523 do {
1524 if (p == null)
1525 p = tab[i++];
1526 else {
1527 action.accept(p.key);
1528 p = p.next;
1529 }
1530 } while (p != null || i < hi);
1531 if (m.modCount != mc)
1532 throw new ConcurrentModificationException();
1533 }
1534 }
1535
1536 public boolean tryAdvance(Consumer<? super K> action) {
1537 int hi;
1538 if (action == null)
1539 throw new NullPointerException();
1540 Node<K,V>[] tab = map.table;
1541 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1542 while (current != null || index < hi) {
1543 if (current == null)
1544 current = tab[index++];
1545 else {
1546 K k = current.key;
1547 current = current.next;
1548 action.accept(k);
1549 if (map.modCount != expectedModCount)
1550 throw new ConcurrentModificationException();
1551 return true;
1552 }
1553 }
1554 }
1555 return false;
1556 }
1557
1558 public int characteristics() {
1559 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1560 Spliterator.DISTINCT;
1561 }
1562 }
1563
1564 static final class ValueSpliterator<K,V>
1565 extends HashMapSpliterator<K,V>
1566 implements Spliterator<V> {
1567 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1568 int expectedModCount) {
1569 super(m, origin, fence, est, expectedModCount);
1570 }
1571
1572 public ValueSpliterator<K,V> trySplit() {
1573 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1574 return (lo >= mid || current != null) ? null :
1575 new ValueSpliterator<K,V>(map, lo, index = mid, est >>>= 1,
1576 expectedModCount);
1577 }
1578
1579 public void forEachRemaining(Consumer<? super V> action) {
1580 int i, hi, mc;
1581 if (action == null)
1582 throw new NullPointerException();
1583 HashMap<K,V> m = map;
1584 Node<K,V>[] tab = m.table;
1585 if ((hi = fence) < 0) {
1586 mc = expectedModCount = m.modCount;
1587 hi = fence = (tab == null) ? 0 : tab.length;
1588 }
1589 else
1590 mc = expectedModCount;
1591 if (tab != null && tab.length >= hi &&
1592 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1593 Node<K,V> p = current;
1594 current = null;
1595 do {
1596 if (p == null)
1597 p = tab[i++];
1598 else {
1599 action.accept(p.value);
1600 p = p.next;
1601 }
1602 } while (p != null || i < hi);
1603 if (m.modCount != mc)
1604 throw new ConcurrentModificationException();
1605 }
1606 }
1607
1608 public boolean tryAdvance(Consumer<? super V> action) {
1609 int hi;
1610 if (action == null)
1611 throw new NullPointerException();
1612 Node<K,V>[] tab = map.table;
1613 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1614 while (current != null || index < hi) {
1615 if (current == null)
1616 current = tab[index++];
1617 else {
1618 V v = current.value;
1619 current = current.next;
1620 action.accept(v);
1621 if (map.modCount != expectedModCount)
1622 throw new ConcurrentModificationException();
1623 return true;
1624 }
1625 }
1626 }
1627 return false;
1628 }
1629
1630 public int characteristics() {
1631 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1632 }
1633 }
1634
1635 static final class EntrySpliterator<K,V>
1636 extends HashMapSpliterator<K,V>
1637 implements Spliterator<Map.Entry<K,V>> {
1638 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1639 int expectedModCount) {
1640 super(m, origin, fence, est, expectedModCount);
1641 }
1642
1643 public EntrySpliterator<K,V> trySplit() {
1644 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1645 return (lo >= mid || current != null) ? null :
1646 new EntrySpliterator<K,V>(map, lo, index = mid, est >>>= 1,
1647 expectedModCount);
1648 }
1649
1650 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1651 int i, hi, mc;
1652 if (action == null)
1653 throw new NullPointerException();
1654 HashMap<K,V> m = map;
1655 Node<K,V>[] tab = m.table;
1656 if ((hi = fence) < 0) {
1657 mc = expectedModCount = m.modCount;
1658 hi = fence = (tab == null) ? 0 : tab.length;
1659 }
1660 else
1661 mc = expectedModCount;
1662 if (tab != null && tab.length >= hi &&
1663 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1664 Node<K,V> p = current;
1665 current = null;
1666 do {
1667 if (p == null)
1668 p = tab[i++];
1669 else {
1670 action.accept(p);
1671 p = p.next;
1672 }
1673 } while (p != null || i < hi);
1674 if (m.modCount != mc)
1675 throw new ConcurrentModificationException();
1676 }
1677 }
1678
1679 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1680 int hi;
1681 if (action == null)
1682 throw new NullPointerException();
1683 Node<K,V>[] tab = map.table;
1684 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1685 while (current != null || index < hi) {
1686 if (current == null)
1687 current = tab[index++];
1688 else {
1689 Node<K,V> e = current;
1690 current = current.next;
1691 action.accept(e);
1692 if (map.modCount != expectedModCount)
1693 throw new ConcurrentModificationException();
1694 return true;
1695 }
1696 }
1697 }
1698 return false;
1699 }
1700
1701 public int characteristics() {
1702 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1703 Spliterator.DISTINCT;
1704 }
1705 }
1706
1707 /* ------------------------------------------------------------ */
1708 // LinkedHashMap support
1709
1710
1711 /*
1712 * The following package-protected methods are designed to be
1713 * overridden by LinkedHashMap, but not by any other subclass.
1714 * Nearly all other internal methods are also package-protected
1715 * but are declared final, so can be used by LinkedHashMap, view
1716 * classes, and HashSet.
1717 */
1718
1719 // Create a regular (non-tree) node
1720 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1721 return new Node<K,V>(hash, key, value, next);
1722 }
1723
1724 // For conversion from TreeNodes to plain nodes
1725 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1726 return new Node<K,V>(p.hash, p.key, p.value, next);
1727 }
1728
1729 // Create a tree bin node
1730 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1731 return new TreeNode<K,V>(hash, key, value, next);
1732 }
1733
1734 // For treeifyBin
1735 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1736 return new TreeNode<K,V>(p.hash, p.key, p.value, next);
1737 }
1738
1739 /**
1740 * Reset to initial default state. Called by clone and readObject.
1741 */
1742 void reinitialize() {
1743 table = null;
1744 entrySet = null;
1745 keySet = null;
1746 values = null;
1747 modCount = 0;
1748 threshold = 0;
1749 size = 0;
1750 }
1751
1752 // Callbacks to allow LinkedHashMap post-actions
1753 void afterNodeAccess(Node<K,V> p) { }
1754 void afterNodeInsertion(boolean evict) { }
1755 void afterNodeRemoval(Node<K,V> p) { }
1756
1757 // Called only from writeObject, to ensure compatible ordering.
1758 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1759 Node<K,V>[] tab;
1760 if (size > 0 && (tab = table) != null) {
1761 for (int i = 0; i < tab.length; ++i) {
1762 for (Node<K,V> e = tab[i]; e != null; e = e.next) {
1763 s.writeObject(e.key);
1764 s.writeObject(e.value);
1765 }
1766 }
1767 }
1768 }
1769
1770 /* ------------------------------------------------------------ */
1771 // Tree bins
1772
1773 /**
1774 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1775 * extends Node) so can be used as extension of either regular or
1776 * linked node.
1777 */
1778 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1779 TreeNode<K,V> parent; // red-black tree links
1780 TreeNode<K,V> left;
1781 TreeNode<K,V> right;
1782 TreeNode<K,V> prev; // needed to unlink next upon deletion
1783 boolean red;
1784 TreeNode(int hash, K key, V val, Node<K,V> next) {
1785 super(hash, key, val, next);
1786 }
1787
1788 /**
1789 * Returns root of tree containing this node.
1790 */
1791 final TreeNode<K,V> root() {
1792 for (TreeNode<K,V> r = this, p;;) {
1793 if ((p = r.parent) == null)
1794 return r;
1795 r = p;
1796 }
1797 }
1798
1799 /**
1800 * Ensures that the given root is the first node of its bin.
1801 */
1802 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1803 int n;
1804 if (root != null && tab != null && (n = tab.length) > 0) {
1805 int index = (n - 1) & root.hash;
1806 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1807 if (root != first) {
1808 Node<K,V> rn;
1809 tab[index] = root;
1810 TreeNode<K,V> rp = root.prev;
1811 if ((rn = root.next) != null)
1812 ((TreeNode<K,V>)rn).prev = rp;
1813 if (rp != null)
1814 rp.next = rn;
1815 if (first != null)
1816 first.prev = root;
1817 root.next = first;
1818 root.prev = null;
1819 }
1820 assert checkInvariants(root);
1821 }
1822 }
1823
1824 /**
1825 * Finds the node starting at root p with the given hash and key.
1826 * The kc argument caches comparableClassFor(key) upon first use
1827 * comparing keys.
1828 */
1829 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1830 TreeNode<K,V> p = this;
1831 do {
1832 int ph, dir; K pk;
1833 TreeNode<K,V> pl = p.left, pr = p.right, q;
1834 if ((ph = p.hash) > h)
1835 p = pl;
1836 else if (ph < h)
1837 p = pr;
1838 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1839 return p;
1840 else if (pl == null)
1841 p = pr;
1842 else if (pr == null)
1843 p = pl;
1844 else if ((kc != null ||
1845 (kc = comparableClassFor(k)) != null) &&
1846 (dir = compareComparables(kc, k, pk)) != 0)
1847 p = (dir < 0) ? pl : pr;
1848 else if ((q = pr.find(h, k, kc)) != null)
1849 return q;
1850 else
1851 p = pl;
1852 } while (p != null);
1853 return null;
1854 }
1855
1856 /**
1857 * Calls find for root node.
1858 */
1859 final TreeNode<K,V> getTreeNode(int h, Object k) {
1860 return ((parent != null) ? root() : this).find(h, k, null);
1861 }
1862
1863 /**
1864 * Tie-breaking utility for ordering insertions when equal
1865 * hashCodes and non-comparable. We don't require a total
1866 * order, just a consistent insertion rule to maintain
1867 * equivalence across rebalancings. Tie-breaking further than
1868 * necessary simplifies testing a bit.
1869 */
1870 static int tieBreakOrder(Object a, Object b) {
1871 int d;
1872 if (a == null || b == null ||
1873 (d = a.getClass().getName().
1874 compareTo(b.getClass().getName())) == 0)
1875 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1876 -1 : 1);
1877 return d;
1878 }
1879
1880 /**
1881 * Forms tree of the nodes linked from this node.
1882 * @return root of tree
1883 */
1884 final void treeify(Node<K,V>[] tab) {
1885 TreeNode<K,V> root = null;
1886 for (TreeNode<K,V> x = this, next; x != null; x = next) {
1887 next = (TreeNode<K,V>)x.next;
1888 x.left = x.right = null;
1889 if (root == null) {
1890 x.parent = null;
1891 x.red = false;
1892 root = x;
1893 }
1894 else {
1895 K k = x.key;
1896 int h = x.hash;
1897 Class<?> kc = null;
1898 for (TreeNode<K,V> p = root;;) {
1899 int dir, ph;
1900 K pk = p.key;
1901 if ((ph = p.hash) > h)
1902 dir = -1;
1903 else if (ph < h)
1904 dir = 1;
1905 else if ((kc == null &&
1906 (kc = comparableClassFor(k)) == null) ||
1907 (dir = compareComparables(kc, k, pk)) == 0)
1908 dir = tieBreakOrder(k, pk);
1909
1910 TreeNode<K,V> xp = p;
1911 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1912 x.parent = xp;
1913 if (dir <= 0)
1914 xp.left = x;
1915 else
1916 xp.right = x;
1917 root = balanceInsertion(root, x);
1918 break;
1919 }
1920 }
1921 }
1922 }
1923 moveRootToFront(tab, root);
1924 }
1925
1926 /**
1927 * Returns a list of non-TreeNodes replacing those linked from
1928 * this node.
1929 */
1930 final Node<K,V> untreeify(HashMap<K,V> map) {
1931 Node<K,V> hd = null, tl = null;
1932 for (Node<K,V> q = this; q != null; q = q.next) {
1933 Node<K,V> p = map.replacementNode(q, null);
1934 if (tl == null)
1935 hd = p;
1936 else
1937 tl.next = p;
1938 tl = p;
1939 }
1940 return hd;
1941 }
1942
1943 /**
1944 * Tree version of putVal.
1945 */
1946 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
1947 int h, K k, V v) {
1948 Class<?> kc = null;
1949 boolean searched = false;
1950 TreeNode<K,V> root = (parent != null) ? root() : this;
1951 for (TreeNode<K,V> p = root;;) {
1952 int dir, ph; K pk;
1953 if ((ph = p.hash) > h)
1954 dir = -1;
1955 else if (ph < h)
1956 dir = 1;
1957 else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
1958 return p;
1959 else if ((kc == null &&
1960 (kc = comparableClassFor(k)) == null) ||
1961 (dir = compareComparables(kc, k, pk)) == 0) {
1962 if (!searched) {
1963 TreeNode<K,V> q, ch;
1964 searched = true;
1965 if (((ch = p.left) != null &&
1966 (q = ch.find(h, k, kc)) != null) ||
1967 ((ch = p.right) != null &&
1968 (q = ch.find(h, k, kc)) != null))
1969 return q;
1970 }
1971 dir = tieBreakOrder(k, pk);
1972 }
1973
1974 TreeNode<K,V> xp = p;
1975 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1976 Node<K,V> xpn = xp.next;
1977 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
1978 if (dir <= 0)
1979 xp.left = x;
1980 else
1981 xp.right = x;
1982 xp.next = x;
1983 x.parent = x.prev = xp;
1984 if (xpn != null)
1985 ((TreeNode<K,V>)xpn).prev = x;
1986 moveRootToFront(tab, balanceInsertion(root, x));
1987 return null;
1988 }
1989 }
1990 }
1991
1992 /**
1993 * Removes the given node, that must be present before this call.
1994 * This is messier than typical red-black deletion code because we
1995 * cannot swap the contents of an interior node with a leaf
1996 * successor that is pinned by "next" pointers that are accessible
1997 * independently during traversal. So instead we swap the tree
1998 * linkages. If the current tree appears to have too few nodes,
1999 * the bin is converted back to a plain bin. (The test triggers
2000 * somewhere between 2 and 6 nodes, depending on tree structure).
2001 */
2002 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2003 boolean movable) {
2004 int n;
2005 if (tab == null || (n = tab.length) == 0)
2006 return;
2007 int index = (n - 1) & hash;
2008 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2009 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2010 if (pred == null)
2011 tab[index] = first = succ;
2012 else
2013 pred.next = succ;
2014 if (succ != null)
2015 succ.prev = pred;
2016 if (first == null)
2017 return;
2018 if (root.parent != null)
2019 root = root.root();
2020 if (root == null || root.right == null ||
2021 (rl = root.left) == null || rl.left == null) {
2022 tab[index] = first.untreeify(map); // too small
2023 return;
2024 }
2025 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2026 if (pl != null && pr != null) {
2027 TreeNode<K,V> s = pr, sl;
2028 while ((sl = s.left) != null) // find successor
2029 s = sl;
2030 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2031 TreeNode<K,V> sr = s.right;
2032 TreeNode<K,V> pp = p.parent;
2033 if (s == pr) { // p was s's direct parent
2034 p.parent = s;
2035 s.right = p;
2036 }
2037 else {
2038 TreeNode<K,V> sp = s.parent;
2039 if ((p.parent = sp) != null) {
2040 if (s == sp.left)
2041 sp.left = p;
2042 else
2043 sp.right = p;
2044 }
2045 if ((s.right = pr) != null)
2046 pr.parent = s;
2047 }
2048 p.left = null;
2049 if ((p.right = sr) != null)
2050 sr.parent = p;
2051 if ((s.left = pl) != null)
2052 pl.parent = s;
2053 if ((s.parent = pp) == null)
2054 root = s;
2055 else if (p == pp.left)
2056 pp.left = s;
2057 else
2058 pp.right = s;
2059 if (sr != null)
2060 replacement = sr;
2061 else
2062 replacement = p;
2063 }
2064 else if (pl != null)
2065 replacement = pl;
2066 else if (pr != null)
2067 replacement = pr;
2068 else
2069 replacement = p;
2070 if (replacement != p) {
2071 TreeNode<K,V> pp = replacement.parent = p.parent;
2072 if (pp == null)
2073 root = replacement;
2074 else if (p == pp.left)
2075 pp.left = replacement;
2076 else
2077 pp.right = replacement;
2078 p.left = p.right = p.parent = null;
2079 }
2080
2081 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2082
2083 if (replacement == p) { // detach
2084 TreeNode<K,V> pp = p.parent;
2085 p.parent = null;
2086 if (pp != null) {
2087 if (p == pp.left)
2088 pp.left = null;
2089 else if (p == pp.right)
2090 pp.right = null;
2091 }
2092 }
2093 if (movable)
2094 moveRootToFront(tab, r);
2095 }
2096
2097 /**
2098 * Splits nodes in a tree bin into lower and upper tree bins,
2099 * or untreeifies if now too small. Called only from resize;
2100 * see above discussion about split bits and indices.
2101 *
2102 * @param map the map
2103 * @param tab the table for recording bin heads
2104 * @param index the index of the table being split
2105 * @param bit the bit of hash to split on
2106 */
2107 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2108 TreeNode<K,V> b = this;
2109 // Relink into lo and hi lists, preserving order
2110 TreeNode<K,V> loHead = null, loTail = null;
2111 TreeNode<K,V> hiHead = null, hiTail = null;
2112 int lc = 0, hc = 0;
2113 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2114 next = (TreeNode<K,V>)e.next;
2115 e.next = null;
2116 if ((e.hash & bit) == 0) {
2117 if ((e.prev = loTail) == null)
2118 loHead = e;
2119 else
2120 loTail.next = e;
2121 loTail = e;
2122 ++lc;
2123 }
2124 else {
2125 if ((e.prev = hiTail) == null)
2126 hiHead = e;
2127 else
2128 hiTail.next = e;
2129 hiTail = e;
2130 ++hc;
2131 }
2132 }
2133
2134 if (loHead != null) {
2135 if (lc <= UNTREEIFY_THRESHOLD)
2136 tab[index] = loHead.untreeify(map);
2137 else {
2138 tab[index] = loHead;
2139 if (hiHead != null) // (else is already treeified)
2140 loHead.treeify(tab);
2141 }
2142 }
2143 if (hiHead != null) {
2144 if (hc <= UNTREEIFY_THRESHOLD)
2145 tab[index + bit] = hiHead.untreeify(map);
2146 else {
2147 tab[index + bit] = hiHead;
2148 if (loHead != null)
2149 hiHead.treeify(tab);
2150 }
2151 }
2152 }
2153
2154 /* ------------------------------------------------------------ */
2155 // Red-black tree methods, all adapted from CLR
2156
2157 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2158 TreeNode<K,V> p) {
2159 TreeNode<K,V> r, pp, rl;
2160 if (p != null && (r = p.right) != null) {
2161 if ((rl = p.right = r.left) != null)
2162 rl.parent = p;
2163 if ((pp = r.parent = p.parent) == null)
2164 (root = r).red = false;
2165 else if (pp.left == p)
2166 pp.left = r;
2167 else
2168 pp.right = r;
2169 r.left = p;
2170 p.parent = r;
2171 }
2172 return root;
2173 }
2174
2175 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2176 TreeNode<K,V> p) {
2177 TreeNode<K,V> l, pp, lr;
2178 if (p != null && (l = p.left) != null) {
2179 if ((lr = p.left = l.right) != null)
2180 lr.parent = p;
2181 if ((pp = l.parent = p.parent) == null)
2182 (root = l).red = false;
2183 else if (pp.right == p)
2184 pp.right = l;
2185 else
2186 pp.left = l;
2187 l.right = p;
2188 p.parent = l;
2189 }
2190 return root;
2191 }
2192
2193 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2194 TreeNode<K,V> x) {
2195 x.red = true;
2196 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2197 if ((xp = x.parent) == null) {
2198 x.red = false;
2199 return x;
2200 }
2201 else if (!xp.red || (xpp = xp.parent) == null)
2202 return root;
2203 if (xp == (xppl = xpp.left)) {
2204 if ((xppr = xpp.right) != null && xppr.red) {
2205 xppr.red = false;
2206 xp.red = false;
2207 xpp.red = true;
2208 x = xpp;
2209 }
2210 else {
2211 if (x == xp.right) {
2212 root = rotateLeft(root, x = xp);
2213 xpp = (xp = x.parent) == null ? null : xp.parent;
2214 }
2215 if (xp != null) {
2216 xp.red = false;
2217 if (xpp != null) {
2218 xpp.red = true;
2219 root = rotateRight(root, xpp);
2220 }
2221 }
2222 }
2223 }
2224 else {
2225 if (xppl != null && xppl.red) {
2226 xppl.red = false;
2227 xp.red = false;
2228 xpp.red = true;
2229 x = xpp;
2230 }
2231 else {
2232 if (x == xp.left) {
2233 root = rotateRight(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 = rotateLeft(root, xpp);
2241 }
2242 }
2243 }
2244 }
2245 }
2246 }
2247
2248 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2249 TreeNode<K,V> x) {
2250 for (TreeNode<K,V> xp, xpl, xpr;;) {
2251 if (x == null || x == root)
2252 return root;
2253 else if ((xp = x.parent) == null) {
2254 x.red = false;
2255 return x;
2256 }
2257 else if (x.red) {
2258 x.red = false;
2259 return root;
2260 }
2261 else if ((xpl = xp.left) == x) {
2262 if ((xpr = xp.right) != null && xpr.red) {
2263 xpr.red = false;
2264 xp.red = true;
2265 root = rotateLeft(root, xp);
2266 xpr = (xp = x.parent) == null ? null : xp.right;
2267 }
2268 if (xpr == null)
2269 x = xp;
2270 else {
2271 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2272 if ((sr == null || !sr.red) &&
2273 (sl == null || !sl.red)) {
2274 xpr.red = true;
2275 x = xp;
2276 }
2277 else {
2278 if (sr == null || !sr.red) {
2279 if (sl != null)
2280 sl.red = false;
2281 xpr.red = true;
2282 root = rotateRight(root, xpr);
2283 xpr = (xp = x.parent) == null ?
2284 null : xp.right;
2285 }
2286 if (xpr != null) {
2287 xpr.red = (xp == null) ? false : xp.red;
2288 if ((sr = xpr.right) != null)
2289 sr.red = false;
2290 }
2291 if (xp != null) {
2292 xp.red = false;
2293 root = rotateLeft(root, xp);
2294 }
2295 x = root;
2296 }
2297 }
2298 }
2299 else { // symmetric
2300 if (xpl != null && xpl.red) {
2301 xpl.red = false;
2302 xp.red = true;
2303 root = rotateRight(root, xp);
2304 xpl = (xp = x.parent) == null ? null : xp.left;
2305 }
2306 if (xpl == null)
2307 x = xp;
2308 else {
2309 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2310 if ((sl == null || !sl.red) &&
2311 (sr == null || !sr.red)) {
2312 xpl.red = true;
2313 x = xp;
2314 }
2315 else {
2316 if (sl == null || !sl.red) {
2317 if (sr != null)
2318 sr.red = false;
2319 xpl.red = true;
2320 root = rotateLeft(root, xpl);
2321 xpl = (xp = x.parent) == null ?
2322 null : xp.left;
2323 }
2324 if (xpl != null) {
2325 xpl.red = (xp == null) ? false : xp.red;
2326 if ((sl = xpl.left) != null)
2327 sl.red = false;
2328 }
2329 if (xp != null) {
2330 xp.red = false;
2331 root = rotateRight(root, xp);
2332 }
2333 x = root;
2334 }
2335 }
2336 }
2337 }
2338 }
2339
2340 /**
2341 * Recursive invariant check
2342 */
2343 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2344 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2345 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2346 if (tb != null && tb.next != t)
2347 return false;
2348 if (tn != null && tn.prev != t)
2349 return false;
2350 if (tp != null && t != tp.left && t != tp.right)
2351 return false;
2352 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2353 return false;
2354 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2355 return false;
2356 if (t.red && tl != null && tl.red && tr != null && tr.red)
2357 return false;
2358 if (tl != null && !checkInvariants(tl))
2359 return false;
2360 if (tr != null && !checkInvariants(tr))
2361 return false;
2362 return true;
2363 }
2364 }
2365
2366 }