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; ParameterizedType p;
348 if ((c = x.getClass()) == String.class) // bypass checks
349 return c;
350 if ((ts = c.getGenericInterfaces()) != null) {
351 for (Type t : ts) {
352 if ((t instanceof ParameterizedType) &&
353 ((p = (ParameterizedType) t).getRawType() ==
354 Comparable.class) &&
355 (as = p.getActualTypeArguments()) != null &&
356 as.length == 1 && as[0] == c) // type arg is c
357 return c;
358 }
359 }
360 }
361 return null;
362 }
363
364 /**
365 * Returns k.compareTo(x) if x matches kc (k's screened comparable
366 * class), else 0.
367 */
368 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
369 static int compareComparables(Class<?> kc, Object k, Object x) {
370 return (x == null || x.getClass() != kc ? 0 :
371 ((Comparable)k).compareTo(x));
372 }
373
374 /**
375 * Returns a power of two size for the given target capacity.
376 */
377 static final int tableSizeFor(int cap) {
378 int n = cap - 1;
379 n |= n >>> 1;
380 n |= n >>> 2;
381 n |= n >>> 4;
382 n |= n >>> 8;
383 n |= n >>> 16;
384 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
385 }
386
387 /* ---------------- Fields -------------- */
388
389 /**
390 * The table, initialized on first use, and resized as
391 * necessary. When allocated, length is always a power of two.
392 * (We also tolerate length zero in some operations to allow
393 * bootstrapping mechanics that are currently not needed.)
394 */
395 transient Node<K,V>[] table;
396
397 /**
398 * Holds cached entrySet(). Note that AbstractMap fields are used
399 * for keySet() and values().
400 */
401 transient Set<Map.Entry<K,V>> entrySet;
402
403 /**
404 * The number of key-value mappings contained in this map.
405 */
406 transient int size;
407
408 /**
409 * The number of times this HashMap has been structurally modified
410 * Structural modifications are those that change the number of mappings in
411 * the HashMap or otherwise modify its internal structure (e.g.,
412 * rehash). This field is used to make iterators on Collection-views of
413 * the HashMap fail-fast. (See ConcurrentModificationException).
414 */
415 transient int modCount;
416
417 /**
418 * The next size value at which to resize (capacity * load factor).
419 *
420 * @serial
421 */
422 // (The javadoc description is true upon serialization.
423 // Additionally, if the table array has not been allocated, this
424 // field holds the initial array capacity, or zero signifying
425 // DEFAULT_INITIAL_CAPACITY.)
426 int threshold;
427
428 /**
429 * The load factor for the hash table.
430 *
431 * @serial
432 */
433 final float loadFactor;
434
435 /* ---------------- Public operations -------------- */
436
437 /**
438 * Constructs an empty <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 (Node<K, V> e : tab) {
879 for (; e != null; e = e.next) {
880 if ((v = e.value) == value ||
881 (value != null && value.equals(v)))
882 return true;
883 }
884 }
885 }
886 return false;
887 }
888
889 /**
890 * Returns a {@link Set} view of the keys contained in this map.
891 * The set is backed by the map, so changes to the map are
892 * reflected in the set, and vice-versa. If the map is modified
893 * while an iteration over the set is in progress (except through
894 * the iterator's own <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<>(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 (Node<K, V> e : tab) {
927 for (; 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<>(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 (Node<K, V> e : tab) {
971 for (; 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<>(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 (Node<K, V> e : tab) {
1034 for (; 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 @Override
1046 public V getOrDefault(Object key, V defaultValue) {
1047 Node<K,V> e;
1048 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1049 }
1050
1051 @Override
1052 public V putIfAbsent(K key, V value) {
1053 return putVal(hash(key), key, value, true, true);
1054 }
1055
1056 @Override
1057 public boolean remove(Object key, Object value) {
1058 return removeNode(hash(key), key, value, true, true) != null;
1059 }
1060
1061 @Override
1062 public boolean replace(K key, V oldValue, V newValue) {
1063 Node<K,V> e; V v;
1064 if ((e = getNode(hash(key), key)) != null &&
1065 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1066 e.value = newValue;
1067 afterNodeAccess(e);
1068 return true;
1069 }
1070 return false;
1071 }
1072
1073 @Override
1074 public V replace(K key, V value) {
1075 Node<K,V> e;
1076 if ((e = getNode(hash(key), key)) != null) {
1077 V oldValue = e.value;
1078 e.value = value;
1079 afterNodeAccess(e);
1080 return oldValue;
1081 }
1082 return null;
1083 }
1084
1085 /**
1086 * {@inheritDoc}
1087 *
1088 * <p>This method will, on a best-effort basis, throw a
1089 * {@link ConcurrentModificationException} if it is detected that the
1090 * mapping function modifies this map during computation.
1091 *
1092 * @throws ConcurrentModificationException if it is detected that the
1093 * mapping function modified this map
1094 */
1095 @Override
1096 public V computeIfAbsent(K key,
1097 Function<? super K, ? extends V> mappingFunction) {
1098 if (mappingFunction == null)
1099 throw new NullPointerException();
1100 int hash = hash(key);
1101 Node<K,V>[] tab; Node<K,V> first; int n, i;
1102 int binCount = 0;
1103 TreeNode<K,V> t = null;
1104 Node<K,V> old = null;
1105 if (size > threshold || (tab = table) == null ||
1106 (n = tab.length) == 0)
1107 n = (tab = resize()).length;
1108 if ((first = tab[i = (n - 1) & hash]) != null) {
1109 if (first instanceof TreeNode)
1110 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1111 else {
1112 Node<K,V> e = first; K k;
1113 do {
1114 if (e.hash == hash &&
1115 ((k = e.key) == key || (key != null && key.equals(k)))) {
1116 old = e;
1117 break;
1118 }
1119 ++binCount;
1120 } while ((e = e.next) != null);
1121 }
1122 V oldValue;
1123 if (old != null && (oldValue = old.value) != null) {
1124 afterNodeAccess(old);
1125 return oldValue;
1126 }
1127 }
1128 int mc = modCount;
1129 V v = mappingFunction.apply(key);
1130 if (mc != modCount) { throw new ConcurrentModificationException(); }
1131 if (v == null) {
1132 return null;
1133 } else if (old != null) {
1134 old.value = v;
1135 afterNodeAccess(old);
1136 return v;
1137 }
1138 else if (t != null)
1139 t.putTreeVal(this, tab, hash, key, v);
1140 else {
1141 tab[i] = newNode(hash, key, v, first);
1142 if (binCount >= TREEIFY_THRESHOLD - 1)
1143 treeifyBin(tab, hash);
1144 }
1145 modCount = mc + 1;
1146 ++size;
1147 afterNodeInsertion(true);
1148 return v;
1149 }
1150
1151 /**
1152 * {@inheritDoc}
1153 *
1154 * <p>This method will, on a best-effort basis, throw a
1155 * {@link ConcurrentModificationException} if it is detected that the
1156 * remapping function modifies this map during computation.
1157 *
1158 * @throws ConcurrentModificationException if it is detected that the
1159 * remapping function modified this map
1160 */
1161 @Override
1162 public V computeIfPresent(K key,
1163 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1164 if (remappingFunction == null)
1165 throw new NullPointerException();
1166 Node<K,V> e; V oldValue;
1167 int hash = hash(key);
1168 if ((e = getNode(hash, key)) != null &&
1169 (oldValue = e.value) != null) {
1170 int mc = modCount;
1171 V v = remappingFunction.apply(key, oldValue);
1172 if (mc != modCount) { throw new ConcurrentModificationException(); }
1173 if (v != null) {
1174 e.value = v;
1175 afterNodeAccess(e);
1176 return v;
1177 }
1178 else
1179 removeNode(hash, key, null, false, true);
1180 }
1181 return null;
1182 }
1183
1184 /**
1185 * {@inheritDoc}
1186 *
1187 * <p>This method will, on a best-effort basis, throw a
1188 * {@link ConcurrentModificationException} if it is detected that the
1189 * remapping function modifies this map during computation.
1190 *
1191 * @throws ConcurrentModificationException if it is detected that the
1192 * remapping function modified this map
1193 */
1194 @Override
1195 public V compute(K key,
1196 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1197 if (remappingFunction == null)
1198 throw new NullPointerException();
1199 int hash = hash(key);
1200 Node<K,V>[] tab; Node<K,V> first; int n, i;
1201 int binCount = 0;
1202 TreeNode<K,V> t = null;
1203 Node<K,V> old = null;
1204 if (size > threshold || (tab = table) == null ||
1205 (n = tab.length) == 0)
1206 n = (tab = resize()).length;
1207 if ((first = tab[i = (n - 1) & hash]) != null) {
1208 if (first instanceof TreeNode)
1209 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1210 else {
1211 Node<K,V> e = first; K k;
1212 do {
1213 if (e.hash == hash &&
1214 ((k = e.key) == key || (key != null && key.equals(k)))) {
1215 old = e;
1216 break;
1217 }
1218 ++binCount;
1219 } while ((e = e.next) != null);
1220 }
1221 }
1222 V oldValue = (old == null) ? null : old.value;
1223 int mc = modCount;
1224 V v = remappingFunction.apply(key, oldValue);
1225 if (mc != modCount) { throw new ConcurrentModificationException(); }
1226 if (old != null) {
1227 if (v != null) {
1228 old.value = v;
1229 afterNodeAccess(old);
1230 }
1231 else
1232 removeNode(hash, key, null, false, true);
1233 }
1234 else if (v != null) {
1235 if (t != null)
1236 t.putTreeVal(this, tab, hash, key, v);
1237 else {
1238 tab[i] = newNode(hash, key, v, first);
1239 if (binCount >= TREEIFY_THRESHOLD - 1)
1240 treeifyBin(tab, hash);
1241 }
1242 modCount = mc + 1;
1243 ++size;
1244 afterNodeInsertion(true);
1245 }
1246 return v;
1247 }
1248
1249 /**
1250 * {@inheritDoc}
1251 *
1252 * <p>This method will, on a best-effort basis, throw a
1253 * {@link ConcurrentModificationException} if it is detected that the
1254 * remapping function modifies this map during computation.
1255 *
1256 * @throws ConcurrentModificationException if it is detected that the
1257 * remapping function modified this map
1258 */
1259 @Override
1260 public V merge(K key, V value,
1261 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1262 if (value == null)
1263 throw new NullPointerException();
1264 if (remappingFunction == null)
1265 throw new NullPointerException();
1266 int hash = hash(key);
1267 Node<K,V>[] tab; Node<K,V> first; int n, i;
1268 int binCount = 0;
1269 TreeNode<K,V> t = null;
1270 Node<K,V> old = null;
1271 if (size > threshold || (tab = table) == null ||
1272 (n = tab.length) == 0)
1273 n = (tab = resize()).length;
1274 if ((first = tab[i = (n - 1) & hash]) != null) {
1275 if (first instanceof TreeNode)
1276 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1277 else {
1278 Node<K,V> e = first; K k;
1279 do {
1280 if (e.hash == hash &&
1281 ((k = e.key) == key || (key != null && key.equals(k)))) {
1282 old = e;
1283 break;
1284 }
1285 ++binCount;
1286 } while ((e = e.next) != null);
1287 }
1288 }
1289 if (old != null) {
1290 V v;
1291 if (old.value != null) {
1292 int mc = modCount;
1293 v = remappingFunction.apply(old.value, value);
1294 if (mc != modCount) {
1295 throw new ConcurrentModificationException();
1296 }
1297 } else {
1298 v = value;
1299 }
1300 if (v != null) {
1301 old.value = v;
1302 afterNodeAccess(old);
1303 }
1304 else
1305 removeNode(hash, key, null, false, true);
1306 return v;
1307 }
1308 if (value != null) {
1309 if (t != null)
1310 t.putTreeVal(this, tab, hash, key, value);
1311 else {
1312 tab[i] = newNode(hash, key, value, first);
1313 if (binCount >= TREEIFY_THRESHOLD - 1)
1314 treeifyBin(tab, hash);
1315 }
1316 ++modCount;
1317 ++size;
1318 afterNodeInsertion(true);
1319 }
1320 return value;
1321 }
1322
1323 @Override
1324 public void forEach(BiConsumer<? super K, ? super V> action) {
1325 Node<K,V>[] tab;
1326 if (action == null)
1327 throw new NullPointerException();
1328 if (size > 0 && (tab = table) != null) {
1329 int mc = modCount;
1330 for (Node<K, V> e : tab) {
1331 for (; e != null; e = e.next)
1332 action.accept(e.key, e.value);
1333 }
1334 if (modCount != mc)
1335 throw new ConcurrentModificationException();
1336 }
1337 }
1338
1339 @Override
1340 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1341 Node<K,V>[] tab;
1342 if (function == null)
1343 throw new NullPointerException();
1344 if (size > 0 && (tab = table) != null) {
1345 int mc = modCount;
1346 for (Node<K, V> e : tab) {
1347 for (; e != null; e = e.next) {
1348 e.value = function.apply(e.key, e.value);
1349 }
1350 }
1351 if (modCount != mc)
1352 throw new ConcurrentModificationException();
1353 }
1354 }
1355
1356 /* ------------------------------------------------------------ */
1357 // Cloning and serialization
1358
1359 /**
1360 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
1361 * values themselves are not cloned.
1362 *
1363 * @return a shallow copy of this map
1364 */
1365 @SuppressWarnings("unchecked")
1366 @Override
1367 public Object clone() {
1368 HashMap<K,V> result;
1369 try {
1370 result = (HashMap<K,V>)super.clone();
1371 } catch (CloneNotSupportedException e) {
1372 // this shouldn't happen, since we are Cloneable
1373 throw new InternalError(e);
1374 }
1375 result.reinitialize();
1376 result.putMapEntries(this, false);
1377 return result;
1378 }
1379
1380 // These methods are also used when serializing HashSets
1381 final float loadFactor() { return loadFactor; }
1382 final int capacity() {
1383 return (table != null) ? table.length :
1384 (threshold > 0) ? threshold :
1385 DEFAULT_INITIAL_CAPACITY;
1386 }
1387
1388 /**
1389 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
1390 * serialize it).
1391 *
1392 * @serialData The <i>capacity</i> of the HashMap (the length of the
1393 * bucket array) is emitted (int), followed by the
1394 * <i>size</i> (an int, the number of key-value
1395 * mappings), followed by the key (Object) and value (Object)
1396 * for each key-value mapping. The key-value mappings are
1397 * emitted in no particular order.
1398 */
1399 private void writeObject(java.io.ObjectOutputStream s)
1400 throws IOException {
1401 int buckets = capacity();
1402 // Write out the threshold, loadfactor, and any hidden stuff
1403 s.defaultWriteObject();
1404 s.writeInt(buckets);
1405 s.writeInt(size);
1406 internalWriteEntries(s);
1407 }
1408
1409 /**
1410 * Reconstitute the {@code HashMap} instance from a stream (i.e.,
1411 * deserialize it).
1412 */
1413 private void readObject(java.io.ObjectInputStream s)
1414 throws IOException, ClassNotFoundException {
1415 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1416 s.defaultReadObject();
1417 reinitialize();
1418 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1419 throw new InvalidObjectException("Illegal load factor: " +
1420 loadFactor);
1421 s.readInt(); // Read and ignore number of buckets
1422 int mappings = s.readInt(); // Read number of mappings (size)
1423 if (mappings < 0)
1424 throw new InvalidObjectException("Illegal mappings count: " +
1425 mappings);
1426 else if (mappings > 0) { // (if zero, use defaults)
1427 // Size the table using given load factor only if within
1428 // range of 0.25...4.0
1429 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1430 float fc = (float)mappings / lf + 1.0f;
1431 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1432 DEFAULT_INITIAL_CAPACITY :
1433 (fc >= MAXIMUM_CAPACITY) ?
1434 MAXIMUM_CAPACITY :
1435 tableSizeFor((int)fc));
1436 float ft = (float)cap * lf;
1437 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1438 (int)ft : Integer.MAX_VALUE);
1439 @SuppressWarnings({"rawtypes","unchecked"})
1440 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1441 table = tab;
1442
1443 // Read the keys and values, and put the mappings in the HashMap
1444 for (int i = 0; i < mappings; i++) {
1445 @SuppressWarnings("unchecked")
1446 K key = (K) s.readObject();
1447 @SuppressWarnings("unchecked")
1448 V value = (V) s.readObject();
1449 putVal(hash(key), key, value, false, false);
1450 }
1451 }
1452 }
1453
1454 /* ------------------------------------------------------------ */
1455 // iterators
1456
1457 abstract class HashIterator {
1458 Node<K,V> next; // next entry to return
1459 Node<K,V> current; // current entry
1460 int expectedModCount; // for fast-fail
1461 int index; // current slot
1462
1463 HashIterator() {
1464 expectedModCount = modCount;
1465 Node<K,V>[] t = table;
1466 current = next = null;
1467 index = 0;
1468 if (t != null && size > 0) { // advance to first entry
1469 do {} while (index < t.length && (next = t[index++]) == null);
1470 }
1471 }
1472
1473 public final boolean hasNext() {
1474 return next != null;
1475 }
1476
1477 final Node<K,V> nextNode() {
1478 Node<K,V>[] t;
1479 Node<K,V> e = next;
1480 if (modCount != expectedModCount)
1481 throw new ConcurrentModificationException();
1482 if (e == null)
1483 throw new NoSuchElementException();
1484 if ((next = (current = e).next) == null && (t = table) != null) {
1485 do {} while (index < t.length && (next = t[index++]) == null);
1486 }
1487 return e;
1488 }
1489
1490 public final void remove() {
1491 Node<K,V> p = current;
1492 if (p == null)
1493 throw new IllegalStateException();
1494 if (modCount != expectedModCount)
1495 throw new ConcurrentModificationException();
1496 current = null;
1497 K key = p.key;
1498 removeNode(hash(key), key, null, false, false);
1499 expectedModCount = modCount;
1500 }
1501 }
1502
1503 final class KeyIterator extends HashIterator
1504 implements Iterator<K> {
1505 public final K next() { return nextNode().key; }
1506 }
1507
1508 final class ValueIterator extends HashIterator
1509 implements Iterator<V> {
1510 public final V next() { return nextNode().value; }
1511 }
1512
1513 final class EntryIterator extends HashIterator
1514 implements Iterator<Map.Entry<K,V>> {
1515 public final Map.Entry<K,V> next() { return nextNode(); }
1516 }
1517
1518 /* ------------------------------------------------------------ */
1519 // spliterators
1520
1521 static class HashMapSpliterator<K,V> {
1522 final HashMap<K,V> map;
1523 Node<K,V> current; // current node
1524 int index; // current index, modified on advance/split
1525 int fence; // one past last index
1526 int est; // size estimate
1527 int expectedModCount; // for comodification checks
1528
1529 HashMapSpliterator(HashMap<K,V> m, int origin,
1530 int fence, int est,
1531 int expectedModCount) {
1532 this.map = m;
1533 this.index = origin;
1534 this.fence = fence;
1535 this.est = est;
1536 this.expectedModCount = expectedModCount;
1537 }
1538
1539 final int getFence() { // initialize fence and size on first use
1540 int hi;
1541 if ((hi = fence) < 0) {
1542 HashMap<K,V> m = map;
1543 est = m.size;
1544 expectedModCount = m.modCount;
1545 Node<K,V>[] tab = m.table;
1546 hi = fence = (tab == null) ? 0 : tab.length;
1547 }
1548 return hi;
1549 }
1550
1551 public final long estimateSize() {
1552 getFence(); // force init
1553 return (long) est;
1554 }
1555 }
1556
1557 static final class KeySpliterator<K,V>
1558 extends HashMapSpliterator<K,V>
1559 implements Spliterator<K> {
1560 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1561 int expectedModCount) {
1562 super(m, origin, fence, est, expectedModCount);
1563 }
1564
1565 public KeySpliterator<K,V> trySplit() {
1566 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1567 return (lo >= mid || current != null) ? null :
1568 new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1569 expectedModCount);
1570 }
1571
1572 public void forEachRemaining(Consumer<? super K> action) {
1573 int i, hi, mc;
1574 if (action == null)
1575 throw new NullPointerException();
1576 HashMap<K,V> m = map;
1577 Node<K,V>[] tab = m.table;
1578 if ((hi = fence) < 0) {
1579 mc = expectedModCount = m.modCount;
1580 hi = fence = (tab == null) ? 0 : tab.length;
1581 }
1582 else
1583 mc = expectedModCount;
1584 if (tab != null && tab.length >= hi &&
1585 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1586 Node<K,V> p = current;
1587 current = null;
1588 do {
1589 if (p == null)
1590 p = tab[i++];
1591 else {
1592 action.accept(p.key);
1593 p = p.next;
1594 }
1595 } while (p != null || i < hi);
1596 if (m.modCount != mc)
1597 throw new ConcurrentModificationException();
1598 }
1599 }
1600
1601 public boolean tryAdvance(Consumer<? super K> action) {
1602 int hi;
1603 if (action == null)
1604 throw new NullPointerException();
1605 Node<K,V>[] tab = map.table;
1606 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1607 while (current != null || index < hi) {
1608 if (current == null)
1609 current = tab[index++];
1610 else {
1611 K k = current.key;
1612 current = current.next;
1613 action.accept(k);
1614 if (map.modCount != expectedModCount)
1615 throw new ConcurrentModificationException();
1616 return true;
1617 }
1618 }
1619 }
1620 return false;
1621 }
1622
1623 public int characteristics() {
1624 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1625 Spliterator.DISTINCT;
1626 }
1627 }
1628
1629 static final class ValueSpliterator<K,V>
1630 extends HashMapSpliterator<K,V>
1631 implements Spliterator<V> {
1632 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1633 int expectedModCount) {
1634 super(m, origin, fence, est, expectedModCount);
1635 }
1636
1637 public ValueSpliterator<K,V> trySplit() {
1638 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1639 return (lo >= mid || current != null) ? null :
1640 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1641 expectedModCount);
1642 }
1643
1644 public void forEachRemaining(Consumer<? super V> action) {
1645 int i, hi, mc;
1646 if (action == null)
1647 throw new NullPointerException();
1648 HashMap<K,V> m = map;
1649 Node<K,V>[] tab = m.table;
1650 if ((hi = fence) < 0) {
1651 mc = expectedModCount = m.modCount;
1652 hi = fence = (tab == null) ? 0 : tab.length;
1653 }
1654 else
1655 mc = expectedModCount;
1656 if (tab != null && tab.length >= hi &&
1657 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1658 Node<K,V> p = current;
1659 current = null;
1660 do {
1661 if (p == null)
1662 p = tab[i++];
1663 else {
1664 action.accept(p.value);
1665 p = p.next;
1666 }
1667 } while (p != null || i < hi);
1668 if (m.modCount != mc)
1669 throw new ConcurrentModificationException();
1670 }
1671 }
1672
1673 public boolean tryAdvance(Consumer<? super V> action) {
1674 int hi;
1675 if (action == null)
1676 throw new NullPointerException();
1677 Node<K,V>[] tab = map.table;
1678 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1679 while (current != null || index < hi) {
1680 if (current == null)
1681 current = tab[index++];
1682 else {
1683 V v = current.value;
1684 current = current.next;
1685 action.accept(v);
1686 if (map.modCount != expectedModCount)
1687 throw new ConcurrentModificationException();
1688 return true;
1689 }
1690 }
1691 }
1692 return false;
1693 }
1694
1695 public int characteristics() {
1696 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1697 }
1698 }
1699
1700 static final class EntrySpliterator<K,V>
1701 extends HashMapSpliterator<K,V>
1702 implements Spliterator<Map.Entry<K,V>> {
1703 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1704 int expectedModCount) {
1705 super(m, origin, fence, est, expectedModCount);
1706 }
1707
1708 public EntrySpliterator<K,V> trySplit() {
1709 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1710 return (lo >= mid || current != null) ? null :
1711 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1712 expectedModCount);
1713 }
1714
1715 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1716 int i, hi, mc;
1717 if (action == null)
1718 throw new NullPointerException();
1719 HashMap<K,V> m = map;
1720 Node<K,V>[] tab = m.table;
1721 if ((hi = fence) < 0) {
1722 mc = expectedModCount = m.modCount;
1723 hi = fence = (tab == null) ? 0 : tab.length;
1724 }
1725 else
1726 mc = expectedModCount;
1727 if (tab != null && tab.length >= hi &&
1728 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1729 Node<K,V> p = current;
1730 current = null;
1731 do {
1732 if (p == null)
1733 p = tab[i++];
1734 else {
1735 action.accept(p);
1736 p = p.next;
1737 }
1738 } while (p != null || i < hi);
1739 if (m.modCount != mc)
1740 throw new ConcurrentModificationException();
1741 }
1742 }
1743
1744 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1745 int hi;
1746 if (action == null)
1747 throw new NullPointerException();
1748 Node<K,V>[] tab = map.table;
1749 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1750 while (current != null || index < hi) {
1751 if (current == null)
1752 current = tab[index++];
1753 else {
1754 Node<K,V> e = current;
1755 current = current.next;
1756 action.accept(e);
1757 if (map.modCount != expectedModCount)
1758 throw new ConcurrentModificationException();
1759 return true;
1760 }
1761 }
1762 }
1763 return false;
1764 }
1765
1766 public int characteristics() {
1767 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1768 Spliterator.DISTINCT;
1769 }
1770 }
1771
1772 /* ------------------------------------------------------------ */
1773 // LinkedHashMap support
1774
1775
1776 /*
1777 * The following package-protected methods are designed to be
1778 * overridden by LinkedHashMap, but not by any other subclass.
1779 * Nearly all other internal methods are also package-protected
1780 * but are declared final, so can be used by LinkedHashMap, view
1781 * classes, and HashSet.
1782 */
1783
1784 // Create a regular (non-tree) node
1785 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1786 return new Node<>(hash, key, value, next);
1787 }
1788
1789 // For conversion from TreeNodes to plain nodes
1790 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1791 return new Node<>(p.hash, p.key, p.value, next);
1792 }
1793
1794 // Create a tree bin node
1795 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1796 return new TreeNode<>(hash, key, value, next);
1797 }
1798
1799 // For treeifyBin
1800 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1801 return new TreeNode<>(p.hash, p.key, p.value, next);
1802 }
1803
1804 /**
1805 * Reset to initial default state. Called by clone and readObject.
1806 */
1807 void reinitialize() {
1808 table = null;
1809 entrySet = null;
1810 keySet = null;
1811 values = null;
1812 modCount = 0;
1813 threshold = 0;
1814 size = 0;
1815 }
1816
1817 // Callbacks to allow LinkedHashMap post-actions
1818 void afterNodeAccess(Node<K,V> p) { }
1819 void afterNodeInsertion(boolean evict) { }
1820 void afterNodeRemoval(Node<K,V> p) { }
1821
1822 // Called only from writeObject, to ensure compatible ordering.
1823 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1824 Node<K,V>[] tab;
1825 if (size > 0 && (tab = table) != null) {
1826 for (Node<K, V> e : tab) {
1827 for (; e != null; e = e.next) {
1828 s.writeObject(e.key);
1829 s.writeObject(e.value);
1830 }
1831 }
1832 }
1833 }
1834
1835 /* ------------------------------------------------------------ */
1836 // Tree bins
1837
1838 /**
1839 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1840 * extends Node) so can be used as extension of either regular or
1841 * linked node.
1842 */
1843 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1844 TreeNode<K,V> parent; // red-black tree links
1845 TreeNode<K,V> left;
1846 TreeNode<K,V> right;
1847 TreeNode<K,V> prev; // needed to unlink next upon deletion
1848 boolean red;
1849 TreeNode(int hash, K key, V val, Node<K,V> next) {
1850 super(hash, key, val, next);
1851 }
1852
1853 /**
1854 * Returns root of tree containing this node.
1855 */
1856 final TreeNode<K,V> root() {
1857 for (TreeNode<K,V> r = this, p;;) {
1858 if ((p = r.parent) == null)
1859 return r;
1860 r = p;
1861 }
1862 }
1863
1864 /**
1865 * Ensures that the given root is the first node of its bin.
1866 */
1867 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1868 int n;
1869 if (root != null && tab != null && (n = tab.length) > 0) {
1870 int index = (n - 1) & root.hash;
1871 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1872 if (root != first) {
1873 Node<K,V> rn;
1874 tab[index] = root;
1875 TreeNode<K,V> rp = root.prev;
1876 if ((rn = root.next) != null)
1877 ((TreeNode<K,V>)rn).prev = rp;
1878 if (rp != null)
1879 rp.next = rn;
1880 if (first != null)
1881 first.prev = root;
1882 root.next = first;
1883 root.prev = null;
1884 }
1885 assert checkInvariants(root);
1886 }
1887 }
1888
1889 /**
1890 * Finds the node starting at root p with the given hash and key.
1891 * The kc argument caches comparableClassFor(key) upon first use
1892 * comparing keys.
1893 */
1894 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1895 TreeNode<K,V> p = this;
1896 do {
1897 int ph, dir; K pk;
1898 TreeNode<K,V> pl = p.left, pr = p.right, q;
1899 if ((ph = p.hash) > h)
1900 p = pl;
1901 else if (ph < h)
1902 p = pr;
1903 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1904 return p;
1905 else if (pl == null)
1906 p = pr;
1907 else if (pr == null)
1908 p = pl;
1909 else if ((kc != null ||
1910 (kc = comparableClassFor(k)) != null) &&
1911 (dir = compareComparables(kc, k, pk)) != 0)
1912 p = (dir < 0) ? pl : pr;
1913 else if ((q = pr.find(h, k, kc)) != null)
1914 return q;
1915 else
1916 p = pl;
1917 } while (p != null);
1918 return null;
1919 }
1920
1921 /**
1922 * Calls find for root node.
1923 */
1924 final TreeNode<K,V> getTreeNode(int h, Object k) {
1925 return ((parent != null) ? root() : this).find(h, k, null);
1926 }
1927
1928 /**
1929 * Tie-breaking utility for ordering insertions when equal
1930 * hashCodes and non-comparable. We don't require a total
1931 * order, just a consistent insertion rule to maintain
1932 * equivalence across rebalancings. Tie-breaking further than
1933 * necessary simplifies testing a bit.
1934 */
1935 static int tieBreakOrder(Object a, Object b) {
1936 int d;
1937 if (a == null || b == null ||
1938 (d = a.getClass().getName().
1939 compareTo(b.getClass().getName())) == 0)
1940 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1941 -1 : 1);
1942 return d;
1943 }
1944
1945 /**
1946 * Forms tree of the nodes linked from this node.
1947 * @return root of tree
1948 */
1949 final void treeify(Node<K,V>[] tab) {
1950 TreeNode<K,V> root = null;
1951 for (TreeNode<K,V> x = this, next; x != null; x = next) {
1952 next = (TreeNode<K,V>)x.next;
1953 x.left = x.right = null;
1954 if (root == null) {
1955 x.parent = null;
1956 x.red = false;
1957 root = x;
1958 }
1959 else {
1960 K k = x.key;
1961 int h = x.hash;
1962 Class<?> kc = null;
1963 for (TreeNode<K,V> p = root;;) {
1964 int dir, ph;
1965 K pk = p.key;
1966 if ((ph = p.hash) > h)
1967 dir = -1;
1968 else if (ph < h)
1969 dir = 1;
1970 else if ((kc == null &&
1971 (kc = comparableClassFor(k)) == null) ||
1972 (dir = compareComparables(kc, k, pk)) == 0)
1973 dir = tieBreakOrder(k, pk);
1974
1975 TreeNode<K,V> xp = p;
1976 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1977 x.parent = xp;
1978 if (dir <= 0)
1979 xp.left = x;
1980 else
1981 xp.right = x;
1982 root = balanceInsertion(root, x);
1983 break;
1984 }
1985 }
1986 }
1987 }
1988 moveRootToFront(tab, root);
1989 }
1990
1991 /**
1992 * Returns a list of non-TreeNodes replacing those linked from
1993 * this node.
1994 */
1995 final Node<K,V> untreeify(HashMap<K,V> map) {
1996 Node<K,V> hd = null, tl = null;
1997 for (Node<K,V> q = this; q != null; q = q.next) {
1998 Node<K,V> p = map.replacementNode(q, null);
1999 if (tl == null)
2000 hd = p;
2001 else
2002 tl.next = p;
2003 tl = p;
2004 }
2005 return hd;
2006 }
2007
2008 /**
2009 * Tree version of putVal.
2010 */
2011 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
2012 int h, K k, V v) {
2013 Class<?> kc = null;
2014 boolean searched = false;
2015 TreeNode<K,V> root = (parent != null) ? root() : this;
2016 for (TreeNode<K,V> p = root;;) {
2017 int dir, ph; K pk;
2018 if ((ph = p.hash) > h)
2019 dir = -1;
2020 else if (ph < h)
2021 dir = 1;
2022 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
2023 return p;
2024 else if ((kc == null &&
2025 (kc = comparableClassFor(k)) == null) ||
2026 (dir = compareComparables(kc, k, pk)) == 0) {
2027 if (!searched) {
2028 TreeNode<K,V> q, ch;
2029 searched = true;
2030 if (((ch = p.left) != null &&
2031 (q = ch.find(h, k, kc)) != null) ||
2032 ((ch = p.right) != null &&
2033 (q = ch.find(h, k, kc)) != null))
2034 return q;
2035 }
2036 dir = tieBreakOrder(k, pk);
2037 }
2038
2039 TreeNode<K,V> xp = p;
2040 if ((p = (dir <= 0) ? p.left : p.right) == null) {
2041 Node<K,V> xpn = xp.next;
2042 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
2043 if (dir <= 0)
2044 xp.left = x;
2045 else
2046 xp.right = x;
2047 xp.next = x;
2048 x.parent = x.prev = xp;
2049 if (xpn != null)
2050 ((TreeNode<K,V>)xpn).prev = x;
2051 moveRootToFront(tab, balanceInsertion(root, x));
2052 return null;
2053 }
2054 }
2055 }
2056
2057 /**
2058 * Removes the given node, that must be present before this call.
2059 * This is messier than typical red-black deletion code because we
2060 * cannot swap the contents of an interior node with a leaf
2061 * successor that is pinned by "next" pointers that are accessible
2062 * independently during traversal. So instead we swap the tree
2063 * linkages. If the current tree appears to have too few nodes,
2064 * the bin is converted back to a plain bin. (The test triggers
2065 * somewhere between 2 and 6 nodes, depending on tree structure).
2066 */
2067 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2068 boolean movable) {
2069 int n;
2070 if (tab == null || (n = tab.length) == 0)
2071 return;
2072 int index = (n - 1) & hash;
2073 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2074 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2075 if (pred == null)
2076 tab[index] = first = succ;
2077 else
2078 pred.next = succ;
2079 if (succ != null)
2080 succ.prev = pred;
2081 if (first == null)
2082 return;
2083 if (root.parent != null)
2084 root = root.root();
2085 if (root == null || root.right == null ||
2086 (rl = root.left) == null || rl.left == null) {
2087 tab[index] = first.untreeify(map); // too small
2088 return;
2089 }
2090 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2091 if (pl != null && pr != null) {
2092 TreeNode<K,V> s = pr, sl;
2093 while ((sl = s.left) != null) // find successor
2094 s = sl;
2095 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2096 TreeNode<K,V> sr = s.right;
2097 TreeNode<K,V> pp = p.parent;
2098 if (s == pr) { // p was s's direct parent
2099 p.parent = s;
2100 s.right = p;
2101 }
2102 else {
2103 TreeNode<K,V> sp = s.parent;
2104 if ((p.parent = sp) != null) {
2105 if (s == sp.left)
2106 sp.left = p;
2107 else
2108 sp.right = p;
2109 }
2110 if ((s.right = pr) != null)
2111 pr.parent = s;
2112 }
2113 p.left = null;
2114 if ((p.right = sr) != null)
2115 sr.parent = p;
2116 if ((s.left = pl) != null)
2117 pl.parent = s;
2118 if ((s.parent = pp) == null)
2119 root = s;
2120 else if (p == pp.left)
2121 pp.left = s;
2122 else
2123 pp.right = s;
2124 if (sr != null)
2125 replacement = sr;
2126 else
2127 replacement = p;
2128 }
2129 else if (pl != null)
2130 replacement = pl;
2131 else if (pr != null)
2132 replacement = pr;
2133 else
2134 replacement = p;
2135 if (replacement != p) {
2136 TreeNode<K,V> pp = replacement.parent = p.parent;
2137 if (pp == null)
2138 root = replacement;
2139 else if (p == pp.left)
2140 pp.left = replacement;
2141 else
2142 pp.right = replacement;
2143 p.left = p.right = p.parent = null;
2144 }
2145
2146 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2147
2148 if (replacement == p) { // detach
2149 TreeNode<K,V> pp = p.parent;
2150 p.parent = null;
2151 if (pp != null) {
2152 if (p == pp.left)
2153 pp.left = null;
2154 else if (p == pp.right)
2155 pp.right = null;
2156 }
2157 }
2158 if (movable)
2159 moveRootToFront(tab, r);
2160 }
2161
2162 /**
2163 * Splits nodes in a tree bin into lower and upper tree bins,
2164 * or untreeifies if now too small. Called only from resize;
2165 * see above discussion about split bits and indices.
2166 *
2167 * @param map the map
2168 * @param tab the table for recording bin heads
2169 * @param index the index of the table being split
2170 * @param bit the bit of hash to split on
2171 */
2172 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2173 TreeNode<K,V> b = this;
2174 // Relink into lo and hi lists, preserving order
2175 TreeNode<K,V> loHead = null, loTail = null;
2176 TreeNode<K,V> hiHead = null, hiTail = null;
2177 int lc = 0, hc = 0;
2178 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2179 next = (TreeNode<K,V>)e.next;
2180 e.next = null;
2181 if ((e.hash & bit) == 0) {
2182 if ((e.prev = loTail) == null)
2183 loHead = e;
2184 else
2185 loTail.next = e;
2186 loTail = e;
2187 ++lc;
2188 }
2189 else {
2190 if ((e.prev = hiTail) == null)
2191 hiHead = e;
2192 else
2193 hiTail.next = e;
2194 hiTail = e;
2195 ++hc;
2196 }
2197 }
2198
2199 if (loHead != null) {
2200 if (lc <= UNTREEIFY_THRESHOLD)
2201 tab[index] = loHead.untreeify(map);
2202 else {
2203 tab[index] = loHead;
2204 if (hiHead != null) // (else is already treeified)
2205 loHead.treeify(tab);
2206 }
2207 }
2208 if (hiHead != null) {
2209 if (hc <= UNTREEIFY_THRESHOLD)
2210 tab[index + bit] = hiHead.untreeify(map);
2211 else {
2212 tab[index + bit] = hiHead;
2213 if (loHead != null)
2214 hiHead.treeify(tab);
2215 }
2216 }
2217 }
2218
2219 /* ------------------------------------------------------------ */
2220 // Red-black tree methods, all adapted from CLR
2221
2222 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2223 TreeNode<K,V> p) {
2224 TreeNode<K,V> r, pp, rl;
2225 if (p != null && (r = p.right) != null) {
2226 if ((rl = p.right = r.left) != null)
2227 rl.parent = p;
2228 if ((pp = r.parent = p.parent) == null)
2229 (root = r).red = false;
2230 else if (pp.left == p)
2231 pp.left = r;
2232 else
2233 pp.right = r;
2234 r.left = p;
2235 p.parent = r;
2236 }
2237 return root;
2238 }
2239
2240 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2241 TreeNode<K,V> p) {
2242 TreeNode<K,V> l, pp, lr;
2243 if (p != null && (l = p.left) != null) {
2244 if ((lr = p.left = l.right) != null)
2245 lr.parent = p;
2246 if ((pp = l.parent = p.parent) == null)
2247 (root = l).red = false;
2248 else if (pp.right == p)
2249 pp.right = l;
2250 else
2251 pp.left = l;
2252 l.right = p;
2253 p.parent = l;
2254 }
2255 return root;
2256 }
2257
2258 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2259 TreeNode<K,V> x) {
2260 x.red = true;
2261 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2262 if ((xp = x.parent) == null) {
2263 x.red = false;
2264 return x;
2265 }
2266 else if (!xp.red || (xpp = xp.parent) == null)
2267 return root;
2268 if (xp == (xppl = xpp.left)) {
2269 if ((xppr = xpp.right) != null && xppr.red) {
2270 xppr.red = false;
2271 xp.red = false;
2272 xpp.red = true;
2273 x = xpp;
2274 }
2275 else {
2276 if (x == xp.right) {
2277 root = rotateLeft(root, x = xp);
2278 xpp = (xp = x.parent) == null ? null : xp.parent;
2279 }
2280 if (xp != null) {
2281 xp.red = false;
2282 if (xpp != null) {
2283 xpp.red = true;
2284 root = rotateRight(root, xpp);
2285 }
2286 }
2287 }
2288 }
2289 else {
2290 if (xppl != null && xppl.red) {
2291 xppl.red = false;
2292 xp.red = false;
2293 xpp.red = true;
2294 x = xpp;
2295 }
2296 else {
2297 if (x == xp.left) {
2298 root = rotateRight(root, x = xp);
2299 xpp = (xp = x.parent) == null ? null : xp.parent;
2300 }
2301 if (xp != null) {
2302 xp.red = false;
2303 if (xpp != null) {
2304 xpp.red = true;
2305 root = rotateLeft(root, xpp);
2306 }
2307 }
2308 }
2309 }
2310 }
2311 }
2312
2313 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2314 TreeNode<K,V> x) {
2315 for (TreeNode<K,V> xp, xpl, xpr;;) {
2316 if (x == null || x == root)
2317 return root;
2318 else if ((xp = x.parent) == null) {
2319 x.red = false;
2320 return x;
2321 }
2322 else if (x.red) {
2323 x.red = false;
2324 return root;
2325 }
2326 else if ((xpl = xp.left) == x) {
2327 if ((xpr = xp.right) != null && xpr.red) {
2328 xpr.red = false;
2329 xp.red = true;
2330 root = rotateLeft(root, xp);
2331 xpr = (xp = x.parent) == null ? null : xp.right;
2332 }
2333 if (xpr == null)
2334 x = xp;
2335 else {
2336 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2337 if ((sr == null || !sr.red) &&
2338 (sl == null || !sl.red)) {
2339 xpr.red = true;
2340 x = xp;
2341 }
2342 else {
2343 if (sr == null || !sr.red) {
2344 if (sl != null)
2345 sl.red = false;
2346 xpr.red = true;
2347 root = rotateRight(root, xpr);
2348 xpr = (xp = x.parent) == null ?
2349 null : xp.right;
2350 }
2351 if (xpr != null) {
2352 xpr.red = (xp == null) ? false : xp.red;
2353 if ((sr = xpr.right) != null)
2354 sr.red = false;
2355 }
2356 if (xp != null) {
2357 xp.red = false;
2358 root = rotateLeft(root, xp);
2359 }
2360 x = root;
2361 }
2362 }
2363 }
2364 else { // symmetric
2365 if (xpl != null && xpl.red) {
2366 xpl.red = false;
2367 xp.red = true;
2368 root = rotateRight(root, xp);
2369 xpl = (xp = x.parent) == null ? null : xp.left;
2370 }
2371 if (xpl == null)
2372 x = xp;
2373 else {
2374 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2375 if ((sl == null || !sl.red) &&
2376 (sr == null || !sr.red)) {
2377 xpl.red = true;
2378 x = xp;
2379 }
2380 else {
2381 if (sl == null || !sl.red) {
2382 if (sr != null)
2383 sr.red = false;
2384 xpl.red = true;
2385 root = rotateLeft(root, xpl);
2386 xpl = (xp = x.parent) == null ?
2387 null : xp.left;
2388 }
2389 if (xpl != null) {
2390 xpl.red = (xp == null) ? false : xp.red;
2391 if ((sl = xpl.left) != null)
2392 sl.red = false;
2393 }
2394 if (xp != null) {
2395 xp.red = false;
2396 root = rotateRight(root, xp);
2397 }
2398 x = root;
2399 }
2400 }
2401 }
2402 }
2403 }
2404
2405 /**
2406 * Recursive invariant check
2407 */
2408 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2409 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2410 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2411 if (tb != null && tb.next != t)
2412 return false;
2413 if (tn != null && tn.prev != t)
2414 return false;
2415 if (tp != null && t != tp.left && t != tp.right)
2416 return false;
2417 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2418 return false;
2419 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2420 return false;
2421 if (t.red && tl != null && tl.red && tr != null && tr.red)
2422 return false;
2423 if (tl != null && !checkInvariants(tl))
2424 return false;
2425 if (tr != null && !checkInvariants(tr))
2426 return false;
2427 return true;
2428 }
2429 }
2430
2431 }