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 sun.misc.JavaLangAccess;
29 import sun.misc.SharedSecrets;
30
31 import java.io.IOException;
32 import java.io.InvalidObjectException;
33 import java.io.Serializable;
34 import java.lang.reflect.ParameterizedType;
35 import java.lang.reflect.Type;
36 import java.util.function.BiConsumer;
37 import java.util.function.BiFunction;
38 import java.util.function.Consumer;
39 import java.util.function.Function;
40
41 /**
42 * Hash table based implementation of the <tt>Map</tt> interface. This
43 * implementation provides all of the optional map operations, and permits
44 * <tt>null</tt> values and the <tt>null</tt> key. (The <tt>HashMap</tt>
45 * class is roughly equivalent to <tt>Hashtable</tt>, except that it is
46 * unsynchronized and permits nulls.) This class makes no guarantees as to
47 * the order of the map; in particular, it does not guarantee that the order
48 * will remain constant over time.
49 *
50 * <p>This implementation provides constant-time performance for the basic
51 * operations (<tt>get</tt> and <tt>put</tt>), assuming the hash function
52 * disperses the elements properly among the buckets. Iteration over
53 * collection views requires time proportional to the "capacity" of the
54 * <tt>HashMap</tt> instance (the number of buckets) plus its size (the number
55 * of key-value mappings). Thus, it's very important not to set the initial
56 * capacity too high (or the load factor too low) if iteration performance is
57 * important.
58 *
59 * <p>An instance of <tt>HashMap</tt> has two parameters that affect its
60 * performance: <i>initial capacity</i> and <i>load factor</i>. The
61 * <i>capacity</i> is the number of buckets in the hash table, and the initial
62 * capacity is simply the capacity at the time the hash table is created. The
63 * <i>load factor</i> is a measure of how full the hash table is allowed to
64 * get before its capacity is automatically increased. When the number of
65 * entries in the hash table exceeds the product of the load factor and the
66 * current capacity, the hash table is <i>rehashed</i> (that is, internal data
67 * structures are rebuilt) so that the hash table has approximately twice the
68 * number of buckets.
69 *
70 * <p>As a general rule, the default load factor (.75) offers a good
71 * tradeoff between time and space costs. Higher values decrease the
72 * space overhead but increase the lookup cost (reflected in most of
73 * the operations of the <tt>HashMap</tt> class, including
74 * <tt>get</tt> and <tt>put</tt>). The expected number of entries in
75 * the map and its load factor should be taken into account when
76 * setting its initial capacity, so as to minimize the number of
77 * rehash operations. If the initial capacity is greater than the
78 * maximum number of entries divided by the load factor, no rehash
79 * operations will ever occur.
80 *
81 * <p>If many mappings are to be stored in a <tt>HashMap</tt>
82 * instance, creating it with a sufficiently large capacity will allow
83 * the mappings to be stored more efficiently than letting it perform
84 * automatic rehashing as needed to grow the table. Note that using
85 * many keys with the same {@code hashCode()} is a sure way to slow
86 * down performance of any hash table. To ameliorate impact, when keys
87 * are {@link Comparable}, this class may use comparison order among
88 * keys to help break ties.
89 *
90 * <p><strong>Note that this implementation is not synchronized.</strong>
91 * If multiple threads access a hash map concurrently, and at least one of
92 * the threads modifies the map structurally, it <i>must</i> be
93 * synchronized externally. (A structural modification is any operation
94 * that adds or deletes one or more mappings; merely changing the value
95 * associated with a key that an instance already contains is not a
96 * structural modification.) This is typically accomplished by
97 * synchronizing on some object that naturally encapsulates the map.
98 *
99 * If no such object exists, the map should be "wrapped" using the
100 * {@link Collections#synchronizedMap Collections.synchronizedMap}
101 * method. This is best done at creation time, to prevent accidental
102 * unsynchronized access to the map:<pre>
103 * Map m = Collections.synchronizedMap(new HashMap(...));</pre>
104 *
105 * <p>The iterators returned by all of this class's "collection view methods"
106 * are <i>fail-fast</i>: if the map is structurally modified at any time after
107 * the iterator is created, in any way except through the iterator's own
108 * <tt>remove</tt> method, the iterator will throw a
109 * {@link ConcurrentModificationException}. Thus, in the face of concurrent
110 * modification, the iterator fails quickly and cleanly, rather than risking
111 * arbitrary, non-deterministic behavior at an undetermined time in the
112 * future.
113 *
114 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
115 * as it is, generally speaking, impossible to make any hard guarantees in the
116 * presence of unsynchronized concurrent modification. Fail-fast iterators
117 * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
118 * Therefore, it would be wrong to write a program that depended on this
119 * exception for its correctness: <i>the fail-fast behavior of iterators
120 * should be used only to detect bugs.</i>
121 *
122 * <p>This class is a member of the
123 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
124 * Java Collections Framework</a>.
125 *
126 * @param <K> the type of keys maintained by this map
127 * @param <V> the type of mapped values
128 *
129 * @author Doug Lea
130 * @author Josh Bloch
131 * @author Arthur van Hoff
132 * @author Neal Gafter
133 * @see Object#hashCode()
134 * @see Collection
135 * @see Map
136 * @see TreeMap
137 * @see Hashtable
138 * @since 1.2
139 */
140 public class HashMap<K,V> extends AbstractMap<K,V>
141 implements Map<K,V>, Cloneable, Serializable {
142
143 private static final long serialVersionUID = 362498820763181265L;
144
145 /*
146 * Implementation notes.
147 *
148 * This map usually acts as a binned (bucketed) hash table, but
149 * when bins get too large, they are transformed into bins of
150 * TreeNodes, each structured similarly to those in
151 * java.util.TreeMap. Most methods try to use normal bins, but
152 * relay to TreeNode methods when applicable (simply by checking
153 * instanceof a node). Bins of TreeNodes may be traversed and
154 * used like any others, but additionally support faster lookup
155 * when overpopulated. However, since the vast majority of bins in
156 * normal use are not overpopulated, checking for existence of
157 * tree bins may be delayed in the course of table methods.
158 *
159 * Tree bins (i.e., bins whose elements are all TreeNodes) are
160 * ordered primarily by hashCode, but in the case of ties, if two
161 * elements are of the same "class C implements Comparable<C>",
162 * type then their compareTo method is used for ordering. (We
163 * conservatively check generic types via reflection to validate
164 * this -- see method comparableClassFor). The added complexity
165 * of tree bins is worthwhile in providing worst-case O(log n)
166 * operations when keys either have distinct hashes or are
167 * orderable, Thus, performance degrades gracefully under
168 * accidental or malicious usages in which hashCode() methods
169 * return values that are poorly distributed, as well as those in
170 * which many keys share a hashCode, so long as they are also
171 * Comparable. (If neither of these apply, we may waste about a
172 * factor of two in time and space compared to taking no
173 * precautions. But the only known cases stem from poor user
174 * programming practices that are already so slow that this makes
175 * little difference.)
176 *
177 * Because TreeNodes are about twice the size of regular nodes, we
178 * use them only when bins contain enough nodes to warrant use
179 * (see TREEIFY_THRESHOLD). And when they become too small (due to
180 * removal or resizing) they are converted back to plain bins. In
181 * usages with well-distributed user hashCodes, tree bins are
182 * rarely used. Ideally, under random hashCodes, the frequency of
183 * nodes in bins follows a Poisson distribution
184 * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
185 * parameter of about 0.5 on average for the default resizing
186 * threshold of 0.75, although with a large variance because of
187 * resizing granularity. Ignoring variance, the expected
188 * occurrences of list size k are (exp(-0.5) * pow(0.5, k) /
189 * factorial(k)). The first values are:
190 *
191 * 0: 0.60653066
192 * 1: 0.30326533
193 * 2: 0.07581633
194 * 3: 0.01263606
195 * 4: 0.00157952
196 * 5: 0.00015795
197 * 6: 0.00001316
198 * 7: 0.00000094
199 * 8: 0.00000006
200 * more: less than 1 in ten million
201 *
202 * The root of a tree bin is normally its first node. However,
203 * sometimes (currently only upon Iterator.remove), the root might
204 * be elsewhere, but can be recovered following parent links
205 * (method TreeNode.root()).
206 *
207 * All applicable internal methods accept a hash code as an
208 * argument (as normally supplied from a public method), allowing
209 * them to call each other without recomputing user hashCodes.
210 * Most internal methods also accept a "tab" argument, that is
211 * normally the current table, but may be a new or old one when
212 * resizing or converting.
213 *
214 * When bin lists are treeified, split, or untreeified, we keep
215 * them in the same relative access/traversal order (i.e., field
216 * Node.next) to better preserve locality, and to slightly
217 * simplify handling of splits and traversals that invoke
218 * iterator.remove. When using comparators on insertion, to keep a
219 * total ordering (or as close as is required here) across
220 * rebalancings, we compare classes and identityHashCodes as
221 * tie-breakers.
222 *
223 * The use and transitions among plain vs tree modes is
224 * complicated by the existence of subclass LinkedHashMap. See
225 * below for hook methods defined to be invoked upon insertion,
226 * removal and access that allow LinkedHashMap internals to
227 * otherwise remain independent of these mechanics. (This also
228 * requires that a map instance be passed to some utility methods
229 * that may create new nodes.)
230 *
231 * The concurrent-programming-like SSA-based coding style helps
232 * avoid aliasing errors amid all of the twisty pointer operations.
233 */
234
235 /**
236 * The default initial capacity - MUST be a power of two.
237 */
238 static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
239
240 /**
241 * The maximum capacity, used if a higher value is implicitly specified
242 * by either of the constructors with arguments.
243 * MUST be a power of two <= 1<<30.
244 */
245 static final int MAXIMUM_CAPACITY = 1 << 30;
246
247 /**
248 * The load factor used when none specified in constructor.
249 */
250 static final float DEFAULT_LOAD_FACTOR = 0.75f;
251
252 /**
253 * The bin count threshold for using a tree rather than list for a
254 * bin. Bins are converted to trees when adding an element to a
255 * bin with at least this many nodes. The value must be greater
256 * than 2 and should be at least 8 to mesh with assumptions in
257 * tree removal about conversion back to plain bins upon
258 * shrinkage.
259 */
260 static final int TREEIFY_THRESHOLD = 8;
261
262 /**
263 * The bin count threshold for untreeifying a (split) bin during a
264 * resize operation. Should be less than TREEIFY_THRESHOLD, and at
265 * most 6 to mesh with shrinkage detection under removal.
266 */
267 static final int UNTREEIFY_THRESHOLD = 6;
268
269 /**
270 * The smallest table capacity for which bins may be treeified.
271 * (Otherwise the table is resized if too many nodes in a bin.)
272 * Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
273 * between resizing and treeification thresholds.
274 */
275 static final int MIN_TREEIFY_CAPACITY = 64;
276
277 /**
278 * Basic hash bin node, used for most entries. (See below for
279 * TreeNode subclass, and in LinkedHashMap for its Entry subclass.)
280 */
281 static class Node<K,V> implements Map.Entry<K,V> {
282 final int hash;
283 final K key;
284 V value;
285 Node<K,V> next;
286
287 Node(int hash, K key, V value, Node<K,V> next) {
288 this.hash = hash;
289 this.key = key;
290 this.value = value;
291 this.next = next;
292 }
293
294 public final K getKey() { return key; }
295 public final V getValue() { return value; }
296 public final String toString() { return key + "=" + value; }
297
298 public final int hashCode() {
299 return Objects.hashCode(key) ^ Objects.hashCode(value);
300 }
301
302 public final V setValue(V newValue) {
303 V oldValue = value;
304 value = newValue;
305 return oldValue;
306 }
307
308 public final boolean equals(Object o) {
309 if (o == this)
310 return true;
311 if (o instanceof Map.Entry) {
312 Map.Entry<?,?> e = (Map.Entry<?,?>)o;
313 if (Objects.equals(key, e.getKey()) &&
314 Objects.equals(value, e.getValue()))
315 return true;
316 }
317 return false;
318 }
319 }
320
321 /* ---------------- Static utilities -------------- */
322
323 /**
324 * Computes key.hashCode() and spreads (XORs) higher bits of hash
325 * to lower. Because the table uses power-of-two masking, sets of
326 * hashes that vary only in bits above the current mask will
327 * always collide. (Among known examples are sets of Float keys
328 * holding consecutive whole numbers in small tables.) So we
329 * apply a transform that spreads the impact of higher bits
330 * downward. There is a tradeoff between speed, utility, and
331 * quality of bit-spreading. Because many common sets of hashes
332 * are already reasonably distributed (so don't benefit from
333 * spreading), and because we use trees to handle large sets of
334 * collisions in bins, we just XOR some shifted bits in the
335 * cheapest possible way to reduce systematic lossage, as well as
336 * to incorporate impact of the highest bits that would otherwise
337 * never be used in index calculations because of table bounds.
338 */
339 static final int hash(Object key) {
340 int h;
341 return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
342 }
343
344 /**
345 * Function returning TRUE for given Class when it is safe to compare
346 * instances of it among themselves.
347 */
348 private static final Function<Class<?>, Boolean> isSelfComparableClass =
349 new Function<Class<?>, Boolean>() {
350 @Override
351 public Boolean apply(Class<?> c) {
352 Type[] ts, as; ParameterizedType p;
353 if ((ts = c.getGenericInterfaces()) != null) {
354 for (Type t : ts) {
355 if ((t instanceof ParameterizedType) &&
356 ((p = (ParameterizedType) t).getRawType() ==
357 Comparable.class) &&
358 (as = p.getActualTypeArguments()) != null &&
359 as.length == 1 && as[0] == c) // type arg is c
360 return Boolean.TRUE;
361 }
362 }
363 return Boolean.FALSE;
364 }
365 };
366
367 /**
368 * Returns x's Class if it is of the form "class C implements
369 * Comparable<C>", else null.
370 */
371 static Class<?> comparableClassFor(Object x) {
372 if (x instanceof Comparable) {
373 Class<?> c;
374 if ((c = x.getClass()) == String.class) { // bypass checks
375 return c;
376 }
377 JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
378 Boolean scc = (jla != null)
379 ? jla.getGenericDerivative(c, isSelfComparableClass, isSelfComparableClass)
380 : isSelfComparableClass.apply(c); // in case very early in boot-up sequence
381 if (scc != null && scc) {
382 return c;
383 }
384 }
385 return null;
386 }
387
388 /**
389 * Returns k.compareTo(x) if x matches kc (k's screened comparable
390 * class), else 0.
391 */
392 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
393 static int compareComparables(Class<?> kc, Object k, Object x) {
394 return (x == null || x.getClass() != kc ? 0 :
395 ((Comparable)k).compareTo(x));
396 }
397
398 /**
399 * Returns a power of two size for the given target capacity.
400 */
401 static final int tableSizeFor(int cap) {
402 int n = cap - 1;
403 n |= n >>> 1;
404 n |= n >>> 2;
405 n |= n >>> 4;
406 n |= n >>> 8;
407 n |= n >>> 16;
408 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
409 }
410
411 /* ---------------- Fields -------------- */
412
413 /**
414 * The table, initialized on first use, and resized as
415 * necessary. When allocated, length is always a power of two.
416 * (We also tolerate length zero in some operations to allow
417 * bootstrapping mechanics that are currently not needed.)
418 */
419 transient Node<K,V>[] table;
420
421 /**
422 * Holds cached entrySet(). Note that AbstractMap fields are used
423 * for keySet() and values().
424 */
425 transient Set<Map.Entry<K,V>> entrySet;
426
427 /**
428 * The number of key-value mappings contained in this map.
429 */
430 transient int size;
431
432 /**
433 * The number of times this HashMap has been structurally modified
434 * Structural modifications are those that change the number of mappings in
435 * the HashMap or otherwise modify its internal structure (e.g.,
436 * rehash). This field is used to make iterators on Collection-views of
437 * the HashMap fail-fast. (See ConcurrentModificationException).
438 */
439 transient int modCount;
440
441 /**
442 * The next size value at which to resize (capacity * load factor).
443 *
444 * @serial
445 */
446 // (The javadoc description is true upon serialization.
447 // Additionally, if the table array has not been allocated, this
448 // field holds the initial array capacity, or zero signifying
449 // DEFAULT_INITIAL_CAPACITY.)
450 int threshold;
451
452 /**
453 * The load factor for the hash table.
454 *
455 * @serial
456 */
457 final float loadFactor;
458
459 /* ---------------- Public operations -------------- */
460
461 /**
462 * Constructs an empty <tt>HashMap</tt> with the specified initial
463 * capacity and load factor.
464 *
465 * @param initialCapacity the initial capacity
466 * @param loadFactor the load factor
467 * @throws IllegalArgumentException if the initial capacity is negative
468 * or the load factor is nonpositive
469 */
470 public HashMap(int initialCapacity, float loadFactor) {
471 if (initialCapacity < 0)
472 throw new IllegalArgumentException("Illegal initial capacity: " +
473 initialCapacity);
474 if (initialCapacity > MAXIMUM_CAPACITY)
475 initialCapacity = MAXIMUM_CAPACITY;
476 if (loadFactor <= 0 || Float.isNaN(loadFactor))
477 throw new IllegalArgumentException("Illegal load factor: " +
478 loadFactor);
479 this.loadFactor = loadFactor;
480 this.threshold = tableSizeFor(initialCapacity);
481 }
482
483 /**
484 * Constructs an empty <tt>HashMap</tt> with the specified initial
485 * capacity and the default load factor (0.75).
486 *
487 * @param initialCapacity the initial capacity.
488 * @throws IllegalArgumentException if the initial capacity is negative.
489 */
490 public HashMap(int initialCapacity) {
491 this(initialCapacity, DEFAULT_LOAD_FACTOR);
492 }
493
494 /**
495 * Constructs an empty <tt>HashMap</tt> with the default initial capacity
496 * (16) and the default load factor (0.75).
497 */
498 public HashMap() {
499 this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
500 }
501
502 /**
503 * Constructs a new <tt>HashMap</tt> with the same mappings as the
504 * specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
505 * default load factor (0.75) and an initial capacity sufficient to
506 * hold the mappings in the specified <tt>Map</tt>.
507 *
508 * @param m the map whose mappings are to be placed in this map
509 * @throws NullPointerException if the specified map is null
510 */
511 public HashMap(Map<? extends K, ? extends V> m) {
512 this.loadFactor = DEFAULT_LOAD_FACTOR;
513 putMapEntries(m, false);
514 }
515
516 /**
517 * Implements Map.putAll and Map constructor
518 *
519 * @param m the map
520 * @param evict false when initially constructing this map, else
521 * true (relayed to method afterNodeInsertion).
522 */
523 final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
524 int s = m.size();
525 if (s > 0) {
526 if (table == null) { // pre-size
527 float ft = ((float)s / loadFactor) + 1.0F;
528 int t = ((ft < (float)MAXIMUM_CAPACITY) ?
529 (int)ft : MAXIMUM_CAPACITY);
530 if (t > threshold)
531 threshold = tableSizeFor(t);
532 }
533 else if (s > threshold)
534 resize();
535 for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
536 K key = e.getKey();
537 V value = e.getValue();
538 putVal(hash(key), key, value, false, evict);
539 }
540 }
541 }
542
543 /**
544 * Returns the number of key-value mappings in this map.
545 *
546 * @return the number of key-value mappings in this map
547 */
548 public int size() {
549 return size;
550 }
551
552 /**
553 * Returns <tt>true</tt> if this map contains no key-value mappings.
554 *
555 * @return <tt>true</tt> if this map contains no key-value mappings
556 */
557 public boolean isEmpty() {
558 return size == 0;
559 }
560
561 /**
562 * Returns the value to which the specified key is mapped,
563 * or {@code null} if this map contains no mapping for the key.
564 *
565 * <p>More formally, if this map contains a mapping from a key
566 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
567 * key.equals(k))}, then this method returns {@code v}; otherwise
568 * it returns {@code null}. (There can be at most one such mapping.)
569 *
570 * <p>A return value of {@code null} does not <i>necessarily</i>
571 * indicate that the map contains no mapping for the key; it's also
572 * possible that the map explicitly maps the key to {@code null}.
573 * The {@link #containsKey containsKey} operation may be used to
574 * distinguish these two cases.
575 *
576 * @see #put(Object, Object)
577 */
578 public V get(Object key) {
579 Node<K,V> e;
580 return (e = getNode(hash(key), key)) == null ? null : e.value;
581 }
582
583 /**
584 * Implements Map.get and related methods
585 *
586 * @param hash hash for key
587 * @param key the key
588 * @return the node, or null if none
589 */
590 final Node<K,V> getNode(int hash, Object key) {
591 Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
592 if ((tab = table) != null && (n = tab.length) > 0 &&
593 (first = tab[(n - 1) & hash]) != null) {
594 if (first.hash == hash && // always check first node
595 ((k = first.key) == key || (key != null && key.equals(k))))
596 return first;
597 if ((e = first.next) != null) {
598 if (first instanceof TreeNode)
599 return ((TreeNode<K,V>)first).getTreeNode(hash, key);
600 do {
601 if (e.hash == hash &&
602 ((k = e.key) == key || (key != null && key.equals(k))))
603 return e;
604 } while ((e = e.next) != null);
605 }
606 }
607 return null;
608 }
609
610 /**
611 * Returns <tt>true</tt> if this map contains a mapping for the
612 * specified key.
613 *
614 * @param key The key whose presence in this map is to be tested
615 * @return <tt>true</tt> if this map contains a mapping for the specified
616 * key.
617 */
618 public boolean containsKey(Object key) {
619 return getNode(hash(key), key) != null;
620 }
621
622 /**
623 * Associates the specified value with the specified key in this map.
624 * If the map previously contained a mapping for the key, the old
625 * value is replaced.
626 *
627 * @param key key with which the specified value is to be associated
628 * @param value value to be associated with the specified key
629 * @return the previous value associated with <tt>key</tt>, or
630 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
631 * (A <tt>null</tt> return can also indicate that the map
632 * previously associated <tt>null</tt> with <tt>key</tt>.)
633 */
634 public V put(K key, V value) {
635 return putVal(hash(key), key, value, false, true);
636 }
637
638 /**
639 * Implements Map.put and related methods
640 *
641 * @param hash hash for key
642 * @param key the key
643 * @param value the value to put
644 * @param onlyIfAbsent if true, don't change existing value
645 * @param evict if false, the table is in creation mode.
646 * @return previous value, or null if none
647 */
648 final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
649 boolean evict) {
650 Node<K,V>[] tab; Node<K,V> p; int n, i;
651 if ((tab = table) == null || (n = tab.length) == 0)
652 n = (tab = resize()).length;
653 if ((p = tab[i = (n - 1) & hash]) == null)
654 tab[i] = newNode(hash, key, value, null);
655 else {
656 Node<K,V> e; K k;
657 if (p.hash == hash &&
658 ((k = p.key) == key || (key != null && key.equals(k))))
659 e = p;
660 else if (p instanceof TreeNode)
661 e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
662 else {
663 for (int binCount = 0; ; ++binCount) {
664 if ((e = p.next) == null) {
665 p.next = newNode(hash, key, value, null);
666 if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
667 treeifyBin(tab, hash);
668 break;
669 }
670 if (e.hash == hash &&
671 ((k = e.key) == key || (key != null && key.equals(k))))
672 break;
673 p = e;
674 }
675 }
676 if (e != null) { // existing mapping for key
677 V oldValue = e.value;
678 if (!onlyIfAbsent || oldValue == null)
679 e.value = value;
680 afterNodeAccess(e);
681 return oldValue;
682 }
683 }
684 ++modCount;
685 if (++size > threshold)
686 resize();
687 afterNodeInsertion(evict);
688 return null;
689 }
690
691 /**
692 * Initializes or doubles table size. If null, allocates in
693 * accord with initial capacity target held in field threshold.
694 * Otherwise, because we are using power-of-two expansion, the
695 * elements from each bin must either stay at same index, or move
696 * with a power of two offset in the new table.
697 *
698 * @return the table
699 */
700 final Node<K,V>[] resize() {
701 Node<K,V>[] oldTab = table;
702 int oldCap = (oldTab == null) ? 0 : oldTab.length;
703 int oldThr = threshold;
704 int newCap, newThr = 0;
705 if (oldCap > 0) {
706 if (oldCap >= MAXIMUM_CAPACITY) {
707 threshold = Integer.MAX_VALUE;
708 return oldTab;
709 }
710 else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
711 oldCap >= DEFAULT_INITIAL_CAPACITY)
712 newThr = oldThr << 1; // double threshold
713 }
714 else if (oldThr > 0) // initial capacity was placed in threshold
715 newCap = oldThr;
716 else { // zero initial threshold signifies using defaults
717 newCap = DEFAULT_INITIAL_CAPACITY;
718 newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
719 }
720 if (newThr == 0) {
721 float ft = (float)newCap * loadFactor;
722 newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
723 (int)ft : Integer.MAX_VALUE);
724 }
725 threshold = newThr;
726 @SuppressWarnings({"rawtypes","unchecked"})
727 Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
728 table = newTab;
729 if (oldTab != null) {
730 for (int j = 0; j < oldCap; ++j) {
731 Node<K,V> e;
732 if ((e = oldTab[j]) != null) {
733 oldTab[j] = null;
734 if (e.next == null)
735 newTab[e.hash & (newCap - 1)] = e;
736 else if (e instanceof TreeNode)
737 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
738 else { // preserve order
739 Node<K,V> loHead = null, loTail = null;
740 Node<K,V> hiHead = null, hiTail = null;
741 Node<K,V> next;
742 do {
743 next = e.next;
744 if ((e.hash & oldCap) == 0) {
745 if (loTail == null)
746 loHead = e;
747 else
748 loTail.next = e;
749 loTail = e;
750 }
751 else {
752 if (hiTail == null)
753 hiHead = e;
754 else
755 hiTail.next = e;
756 hiTail = e;
757 }
758 } while ((e = next) != null);
759 if (loTail != null) {
760 loTail.next = null;
761 newTab[j] = loHead;
762 }
763 if (hiTail != null) {
764 hiTail.next = null;
765 newTab[j + oldCap] = hiHead;
766 }
767 }
768 }
769 }
770 }
771 return newTab;
772 }
773
774 /**
775 * Replaces all linked nodes in bin at index for given hash unless
776 * table is too small, in which case resizes instead.
777 */
778 final void treeifyBin(Node<K,V>[] tab, int hash) {
779 int n, index; Node<K,V> e;
780 if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
781 resize();
782 else if ((e = tab[index = (n - 1) & hash]) != null) {
783 TreeNode<K,V> hd = null, tl = null;
784 do {
785 TreeNode<K,V> p = replacementTreeNode(e, null);
786 if (tl == null)
787 hd = p;
788 else {
789 p.prev = tl;
790 tl.next = p;
791 }
792 tl = p;
793 } while ((e = e.next) != null);
794 if ((tab[index] = hd) != null)
795 hd.treeify(tab);
796 }
797 }
798
799 /**
800 * Copies all of the mappings from the specified map to this map.
801 * These mappings will replace any mappings that this map had for
802 * any of the keys currently in the specified map.
803 *
804 * @param m mappings to be stored in this map
805 * @throws NullPointerException if the specified map is null
806 */
807 public void putAll(Map<? extends K, ? extends V> m) {
808 putMapEntries(m, true);
809 }
810
811 /**
812 * Removes the mapping for the specified key from this map if present.
813 *
814 * @param key key whose mapping is to be removed from the map
815 * @return the previous value associated with <tt>key</tt>, or
816 * <tt>null</tt> if there was no mapping for <tt>key</tt>.
817 * (A <tt>null</tt> return can also indicate that the map
818 * previously associated <tt>null</tt> with <tt>key</tt>.)
819 */
820 public V remove(Object key) {
821 Node<K,V> e;
822 return (e = removeNode(hash(key), key, null, false, true)) == null ?
823 null : e.value;
824 }
825
826 /**
827 * Implements Map.remove and related methods
828 *
829 * @param hash hash for key
830 * @param key the key
831 * @param value the value to match if matchValue, else ignored
832 * @param matchValue if true only remove if value is equal
833 * @param movable if false do not move other nodes while removing
834 * @return the node, or null if none
835 */
836 final Node<K,V> removeNode(int hash, Object key, Object value,
837 boolean matchValue, boolean movable) {
838 Node<K,V>[] tab; Node<K,V> p; int n, index;
839 if ((tab = table) != null && (n = tab.length) > 0 &&
840 (p = tab[index = (n - 1) & hash]) != null) {
841 Node<K,V> node = null, e; K k; V v;
842 if (p.hash == hash &&
843 ((k = p.key) == key || (key != null && key.equals(k))))
844 node = p;
845 else if ((e = p.next) != null) {
846 if (p instanceof TreeNode)
847 node = ((TreeNode<K,V>)p).getTreeNode(hash, key);
848 else {
849 do {
850 if (e.hash == hash &&
851 ((k = e.key) == key ||
852 (key != null && key.equals(k)))) {
853 node = e;
854 break;
855 }
856 p = e;
857 } while ((e = e.next) != null);
858 }
859 }
860 if (node != null && (!matchValue || (v = node.value) == value ||
861 (value != null && value.equals(v)))) {
862 if (node instanceof TreeNode)
863 ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable);
864 else if (node == p)
865 tab[index] = node.next;
866 else
867 p.next = node.next;
868 ++modCount;
869 --size;
870 afterNodeRemoval(node);
871 return node;
872 }
873 }
874 return null;
875 }
876
877 /**
878 * Removes all of the mappings from this map.
879 * The map will be empty after this call returns.
880 */
881 public void clear() {
882 Node<K,V>[] tab;
883 modCount++;
884 if ((tab = table) != null && size > 0) {
885 size = 0;
886 for (int i = 0; i < tab.length; ++i)
887 tab[i] = null;
888 }
889 }
890
891 /**
892 * Returns <tt>true</tt> if this map maps one or more keys to the
893 * specified value.
894 *
895 * @param value value whose presence in this map is to be tested
896 * @return <tt>true</tt> if this map maps one or more keys to the
897 * specified value
898 */
899 public boolean containsValue(Object value) {
900 Node<K,V>[] tab; V v;
901 if ((tab = table) != null && size > 0) {
902 for (Node<K, V> e : tab) {
903 for (; e != null; e = e.next) {
904 if ((v = e.value) == value ||
905 (value != null && value.equals(v)))
906 return true;
907 }
908 }
909 }
910 return false;
911 }
912
913 /**
914 * Returns a {@link Set} view of the keys contained in this map.
915 * The set is backed by the map, so changes to the map are
916 * reflected in the set, and vice-versa. If the map is modified
917 * while an iteration over the set is in progress (except through
918 * the iterator's own <tt>remove</tt> operation), the results of
919 * the iteration are undefined. The set supports element removal,
920 * which removes the corresponding mapping from the map, via the
921 * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
922 * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
923 * operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
924 * operations.
925 *
926 * @return a set view of the keys contained in this map
927 */
928 public Set<K> keySet() {
929 Set<K> ks;
930 return (ks = keySet) == null ? (keySet = new KeySet()) : ks;
931 }
932
933 final class KeySet extends AbstractSet<K> {
934 public final int size() { return size; }
935 public final void clear() { HashMap.this.clear(); }
936 public final Iterator<K> iterator() { return new KeyIterator(); }
937 public final boolean contains(Object o) { return containsKey(o); }
938 public final boolean remove(Object key) {
939 return removeNode(hash(key), key, null, false, true) != null;
940 }
941 public final Spliterator<K> spliterator() {
942 return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
943 }
944 public final void forEach(Consumer<? super K> action) {
945 Node<K,V>[] tab;
946 if (action == null)
947 throw new NullPointerException();
948 if (size > 0 && (tab = table) != null) {
949 int mc = modCount;
950 for (Node<K, V> e : tab) {
951 for (; e != null; e = e.next)
952 action.accept(e.key);
953 }
954 if (modCount != mc)
955 throw new ConcurrentModificationException();
956 }
957 }
958 }
959
960 /**
961 * Returns a {@link Collection} view of the values contained in this map.
962 * The collection is backed by the map, so changes to the map are
963 * reflected in the collection, and vice-versa. If the map is
964 * modified while an iteration over the collection is in progress
965 * (except through the iterator's own <tt>remove</tt> operation),
966 * the results of the iteration are undefined. The collection
967 * supports element removal, which removes the corresponding
968 * mapping from the map, via the <tt>Iterator.remove</tt>,
969 * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
970 * <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
971 * support the <tt>add</tt> or <tt>addAll</tt> operations.
972 *
973 * @return a view of the values contained in this map
974 */
975 public Collection<V> values() {
976 Collection<V> vs;
977 return (vs = values) == null ? (values = new Values()) : vs;
978 }
979
980 final class Values extends AbstractCollection<V> {
981 public final int size() { return size; }
982 public final void clear() { HashMap.this.clear(); }
983 public final Iterator<V> iterator() { return new ValueIterator(); }
984 public final boolean contains(Object o) { return containsValue(o); }
985 public final Spliterator<V> spliterator() {
986 return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
987 }
988 public final void forEach(Consumer<? super V> action) {
989 Node<K,V>[] tab;
990 if (action == null)
991 throw new NullPointerException();
992 if (size > 0 && (tab = table) != null) {
993 int mc = modCount;
994 for (Node<K, V> e : tab) {
995 for (; e != null; e = e.next)
996 action.accept(e.value);
997 }
998 if (modCount != mc)
999 throw new ConcurrentModificationException();
1000 }
1001 }
1002 }
1003
1004 /**
1005 * Returns a {@link Set} view of the mappings contained in this map.
1006 * The set is backed by the map, so changes to the map are
1007 * reflected in the set, and vice-versa. If the map is modified
1008 * while an iteration over the set is in progress (except through
1009 * the iterator's own <tt>remove</tt> operation, or through the
1010 * <tt>setValue</tt> operation on a map entry returned by the
1011 * iterator) the results of the iteration are undefined. The set
1012 * supports element removal, which removes the corresponding
1013 * mapping from the map, via the <tt>Iterator.remove</tt>,
1014 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
1015 * <tt>clear</tt> operations. It does not support the
1016 * <tt>add</tt> or <tt>addAll</tt> operations.
1017 *
1018 * @return a set view of the mappings contained in this map
1019 */
1020 public Set<Map.Entry<K,V>> entrySet() {
1021 Set<Map.Entry<K,V>> es;
1022 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
1023 }
1024
1025 final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1026 public final int size() { return size; }
1027 public final void clear() { HashMap.this.clear(); }
1028 public final Iterator<Map.Entry<K,V>> iterator() {
1029 return new EntryIterator();
1030 }
1031 public final boolean contains(Object o) {
1032 if (!(o instanceof Map.Entry))
1033 return false;
1034 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1035 Object key = e.getKey();
1036 Node<K,V> candidate = getNode(hash(key), key);
1037 return candidate != null && candidate.equals(e);
1038 }
1039 public final boolean remove(Object o) {
1040 if (o instanceof Map.Entry) {
1041 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1042 Object key = e.getKey();
1043 Object value = e.getValue();
1044 return removeNode(hash(key), key, value, true, true) != null;
1045 }
1046 return false;
1047 }
1048 public final Spliterator<Map.Entry<K,V>> spliterator() {
1049 return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
1050 }
1051 public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1052 Node<K,V>[] tab;
1053 if (action == null)
1054 throw new NullPointerException();
1055 if (size > 0 && (tab = table) != null) {
1056 int mc = modCount;
1057 for (Node<K, V> e : tab) {
1058 for (; e != null; e = e.next)
1059 action.accept(e);
1060 }
1061 if (modCount != mc)
1062 throw new ConcurrentModificationException();
1063 }
1064 }
1065 }
1066
1067 // Overrides of JDK8 Map extension methods
1068
1069 @Override
1070 public V getOrDefault(Object key, V defaultValue) {
1071 Node<K,V> e;
1072 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1073 }
1074
1075 @Override
1076 public V putIfAbsent(K key, V value) {
1077 return putVal(hash(key), key, value, true, true);
1078 }
1079
1080 @Override
1081 public boolean remove(Object key, Object value) {
1082 return removeNode(hash(key), key, value, true, true) != null;
1083 }
1084
1085 @Override
1086 public boolean replace(K key, V oldValue, V newValue) {
1087 Node<K,V> e; V v;
1088 if ((e = getNode(hash(key), key)) != null &&
1089 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1090 e.value = newValue;
1091 afterNodeAccess(e);
1092 return true;
1093 }
1094 return false;
1095 }
1096
1097 @Override
1098 public V replace(K key, V value) {
1099 Node<K,V> e;
1100 if ((e = getNode(hash(key), key)) != null) {
1101 V oldValue = e.value;
1102 e.value = value;
1103 afterNodeAccess(e);
1104 return oldValue;
1105 }
1106 return null;
1107 }
1108
1109 @Override
1110 public V computeIfAbsent(K key,
1111 Function<? super K, ? extends V> mappingFunction) {
1112 if (mappingFunction == null)
1113 throw new NullPointerException();
1114 int hash = hash(key);
1115 Node<K,V>[] tab; Node<K,V> first; int n, i;
1116 int binCount = 0;
1117 TreeNode<K,V> t = null;
1118 Node<K,V> old = null;
1119 if (size > threshold || (tab = table) == null ||
1120 (n = tab.length) == 0)
1121 n = (tab = resize()).length;
1122 if ((first = tab[i = (n - 1) & hash]) != null) {
1123 if (first instanceof TreeNode)
1124 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1125 else {
1126 Node<K,V> e = first; K k;
1127 do {
1128 if (e.hash == hash &&
1129 ((k = e.key) == key || (key != null && key.equals(k)))) {
1130 old = e;
1131 break;
1132 }
1133 ++binCount;
1134 } while ((e = e.next) != null);
1135 }
1136 V oldValue;
1137 if (old != null && (oldValue = old.value) != null) {
1138 afterNodeAccess(old);
1139 return oldValue;
1140 }
1141 }
1142 V v = mappingFunction.apply(key);
1143 if (v == null) {
1144 return null;
1145 } else if (old != null) {
1146 old.value = v;
1147 afterNodeAccess(old);
1148 return v;
1149 }
1150 else if (t != null)
1151 t.putTreeVal(this, tab, hash, key, v);
1152 else {
1153 tab[i] = newNode(hash, key, v, first);
1154 if (binCount >= TREEIFY_THRESHOLD - 1)
1155 treeifyBin(tab, hash);
1156 }
1157 ++modCount;
1158 ++size;
1159 afterNodeInsertion(true);
1160 return v;
1161 }
1162
1163 public V computeIfPresent(K key,
1164 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1165 if (remappingFunction == null)
1166 throw new NullPointerException();
1167 Node<K,V> e; V oldValue;
1168 int hash = hash(key);
1169 if ((e = getNode(hash, key)) != null &&
1170 (oldValue = e.value) != null) {
1171 V v = remappingFunction.apply(key, oldValue);
1172 if (v != null) {
1173 e.value = v;
1174 afterNodeAccess(e);
1175 return v;
1176 }
1177 else
1178 removeNode(hash, key, null, false, true);
1179 }
1180 return null;
1181 }
1182
1183 @Override
1184 public V compute(K key,
1185 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1186 if (remappingFunction == null)
1187 throw new NullPointerException();
1188 int hash = hash(key);
1189 Node<K,V>[] tab; Node<K,V> first; int n, i;
1190 int binCount = 0;
1191 TreeNode<K,V> t = null;
1192 Node<K,V> old = null;
1193 if (size > threshold || (tab = table) == null ||
1194 (n = tab.length) == 0)
1195 n = (tab = resize()).length;
1196 if ((first = tab[i = (n - 1) & hash]) != null) {
1197 if (first instanceof TreeNode)
1198 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1199 else {
1200 Node<K,V> e = first; K k;
1201 do {
1202 if (e.hash == hash &&
1203 ((k = e.key) == key || (key != null && key.equals(k)))) {
1204 old = e;
1205 break;
1206 }
1207 ++binCount;
1208 } while ((e = e.next) != null);
1209 }
1210 }
1211 V oldValue = (old == null) ? null : old.value;
1212 V v = remappingFunction.apply(key, oldValue);
1213 if (old != null) {
1214 if (v != null) {
1215 old.value = v;
1216 afterNodeAccess(old);
1217 }
1218 else
1219 removeNode(hash, key, null, false, true);
1220 }
1221 else if (v != null) {
1222 if (t != null)
1223 t.putTreeVal(this, tab, hash, key, v);
1224 else {
1225 tab[i] = newNode(hash, key, v, first);
1226 if (binCount >= TREEIFY_THRESHOLD - 1)
1227 treeifyBin(tab, hash);
1228 }
1229 ++modCount;
1230 ++size;
1231 afterNodeInsertion(true);
1232 }
1233 return v;
1234 }
1235
1236 @Override
1237 public V merge(K key, V value,
1238 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1239 if (value == null)
1240 throw new NullPointerException();
1241 if (remappingFunction == null)
1242 throw new NullPointerException();
1243 int hash = hash(key);
1244 Node<K,V>[] tab; Node<K,V> first; int n, i;
1245 int binCount = 0;
1246 TreeNode<K,V> t = null;
1247 Node<K,V> old = null;
1248 if (size > threshold || (tab = table) == null ||
1249 (n = tab.length) == 0)
1250 n = (tab = resize()).length;
1251 if ((first = tab[i = (n - 1) & hash]) != null) {
1252 if (first instanceof TreeNode)
1253 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1254 else {
1255 Node<K,V> e = first; K k;
1256 do {
1257 if (e.hash == hash &&
1258 ((k = e.key) == key || (key != null && key.equals(k)))) {
1259 old = e;
1260 break;
1261 }
1262 ++binCount;
1263 } while ((e = e.next) != null);
1264 }
1265 }
1266 if (old != null) {
1267 V v;
1268 if (old.value != null)
1269 v = remappingFunction.apply(old.value, value);
1270 else
1271 v = value;
1272 if (v != null) {
1273 old.value = v;
1274 afterNodeAccess(old);
1275 }
1276 else
1277 removeNode(hash, key, null, false, true);
1278 return v;
1279 }
1280 if (value != null) {
1281 if (t != null)
1282 t.putTreeVal(this, tab, hash, key, value);
1283 else {
1284 tab[i] = newNode(hash, key, value, first);
1285 if (binCount >= TREEIFY_THRESHOLD - 1)
1286 treeifyBin(tab, hash);
1287 }
1288 ++modCount;
1289 ++size;
1290 afterNodeInsertion(true);
1291 }
1292 return value;
1293 }
1294
1295 @Override
1296 public void forEach(BiConsumer<? super K, ? super V> action) {
1297 Node<K,V>[] tab;
1298 if (action == null)
1299 throw new NullPointerException();
1300 if (size > 0 && (tab = table) != null) {
1301 int mc = modCount;
1302 for (Node<K, V> e : tab) {
1303 for (; e != null; e = e.next)
1304 action.accept(e.key, e.value);
1305 }
1306 if (modCount != mc)
1307 throw new ConcurrentModificationException();
1308 }
1309 }
1310
1311 @Override
1312 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1313 Node<K,V>[] tab;
1314 if (function == null)
1315 throw new NullPointerException();
1316 if (size > 0 && (tab = table) != null) {
1317 int mc = modCount;
1318 for (Node<K, V> e : tab) {
1319 for (; e != null; e = e.next) {
1320 e.value = function.apply(e.key, e.value);
1321 }
1322 }
1323 if (modCount != mc)
1324 throw new ConcurrentModificationException();
1325 }
1326 }
1327
1328 /* ------------------------------------------------------------ */
1329 // Cloning and serialization
1330
1331 /**
1332 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
1333 * values themselves are not cloned.
1334 *
1335 * @return a shallow copy of this map
1336 */
1337 @SuppressWarnings("unchecked")
1338 @Override
1339 public Object clone() {
1340 HashMap<K,V> result;
1341 try {
1342 result = (HashMap<K,V>)super.clone();
1343 } catch (CloneNotSupportedException e) {
1344 // this shouldn't happen, since we are Cloneable
1345 throw new InternalError(e);
1346 }
1347 result.reinitialize();
1348 result.putMapEntries(this, false);
1349 return result;
1350 }
1351
1352 // These methods are also used when serializing HashSets
1353 final float loadFactor() { return loadFactor; }
1354 final int capacity() {
1355 return (table != null) ? table.length :
1356 (threshold > 0) ? threshold :
1357 DEFAULT_INITIAL_CAPACITY;
1358 }
1359
1360 /**
1361 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
1362 * serialize it).
1363 *
1364 * @serialData The <i>capacity</i> of the HashMap (the length of the
1365 * bucket array) is emitted (int), followed by the
1366 * <i>size</i> (an int, the number of key-value
1367 * mappings), followed by the key (Object) and value (Object)
1368 * for each key-value mapping. The key-value mappings are
1369 * emitted in no particular order.
1370 */
1371 private void writeObject(java.io.ObjectOutputStream s)
1372 throws IOException {
1373 int buckets = capacity();
1374 // Write out the threshold, loadfactor, and any hidden stuff
1375 s.defaultWriteObject();
1376 s.writeInt(buckets);
1377 s.writeInt(size);
1378 internalWriteEntries(s);
1379 }
1380
1381 /**
1382 * Reconstitute the {@code HashMap} instance from a stream (i.e.,
1383 * deserialize it).
1384 */
1385 private void readObject(java.io.ObjectInputStream s)
1386 throws IOException, ClassNotFoundException {
1387 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1388 s.defaultReadObject();
1389 reinitialize();
1390 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1391 throw new InvalidObjectException("Illegal load factor: " +
1392 loadFactor);
1393 s.readInt(); // Read and ignore number of buckets
1394 int mappings = s.readInt(); // Read number of mappings (size)
1395 if (mappings < 0)
1396 throw new InvalidObjectException("Illegal mappings count: " +
1397 mappings);
1398 else if (mappings > 0) { // (if zero, use defaults)
1399 // Size the table using given load factor only if within
1400 // range of 0.25...4.0
1401 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1402 float fc = (float)mappings / lf + 1.0f;
1403 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1404 DEFAULT_INITIAL_CAPACITY :
1405 (fc >= MAXIMUM_CAPACITY) ?
1406 MAXIMUM_CAPACITY :
1407 tableSizeFor((int)fc));
1408 float ft = (float)cap * lf;
1409 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1410 (int)ft : Integer.MAX_VALUE);
1411 @SuppressWarnings({"rawtypes","unchecked"})
1412 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1413 table = tab;
1414
1415 // Read the keys and values, and put the mappings in the HashMap
1416 for (int i = 0; i < mappings; i++) {
1417 @SuppressWarnings("unchecked")
1418 K key = (K) s.readObject();
1419 @SuppressWarnings("unchecked")
1420 V value = (V) s.readObject();
1421 putVal(hash(key), key, value, false, false);
1422 }
1423 }
1424 }
1425
1426 /* ------------------------------------------------------------ */
1427 // iterators
1428
1429 abstract class HashIterator {
1430 Node<K,V> next; // next entry to return
1431 Node<K,V> current; // current entry
1432 int expectedModCount; // for fast-fail
1433 int index; // current slot
1434
1435 HashIterator() {
1436 expectedModCount = modCount;
1437 Node<K,V>[] t = table;
1438 current = next = null;
1439 index = 0;
1440 if (t != null && size > 0) { // advance to first entry
1441 do {} while (index < t.length && (next = t[index++]) == null);
1442 }
1443 }
1444
1445 public final boolean hasNext() {
1446 return next != null;
1447 }
1448
1449 final Node<K,V> nextNode() {
1450 Node<K,V>[] t;
1451 Node<K,V> e = next;
1452 if (modCount != expectedModCount)
1453 throw new ConcurrentModificationException();
1454 if (e == null)
1455 throw new NoSuchElementException();
1456 if ((next = (current = e).next) == null && (t = table) != null) {
1457 do {} while (index < t.length && (next = t[index++]) == null);
1458 }
1459 return e;
1460 }
1461
1462 public final void remove() {
1463 Node<K,V> p = current;
1464 if (p == null)
1465 throw new IllegalStateException();
1466 if (modCount != expectedModCount)
1467 throw new ConcurrentModificationException();
1468 current = null;
1469 K key = p.key;
1470 removeNode(hash(key), key, null, false, false);
1471 expectedModCount = modCount;
1472 }
1473 }
1474
1475 final class KeyIterator extends HashIterator
1476 implements Iterator<K> {
1477 public final K next() { return nextNode().key; }
1478 }
1479
1480 final class ValueIterator extends HashIterator
1481 implements Iterator<V> {
1482 public final V next() { return nextNode().value; }
1483 }
1484
1485 final class EntryIterator extends HashIterator
1486 implements Iterator<Map.Entry<K,V>> {
1487 public final Map.Entry<K,V> next() { return nextNode(); }
1488 }
1489
1490 /* ------------------------------------------------------------ */
1491 // spliterators
1492
1493 static class HashMapSpliterator<K,V> {
1494 final HashMap<K,V> map;
1495 Node<K,V> current; // current node
1496 int index; // current index, modified on advance/split
1497 int fence; // one past last index
1498 int est; // size estimate
1499 int expectedModCount; // for comodification checks
1500
1501 HashMapSpliterator(HashMap<K,V> m, int origin,
1502 int fence, int est,
1503 int expectedModCount) {
1504 this.map = m;
1505 this.index = origin;
1506 this.fence = fence;
1507 this.est = est;
1508 this.expectedModCount = expectedModCount;
1509 }
1510
1511 final int getFence() { // initialize fence and size on first use
1512 int hi;
1513 if ((hi = fence) < 0) {
1514 HashMap<K,V> m = map;
1515 est = m.size;
1516 expectedModCount = m.modCount;
1517 Node<K,V>[] tab = m.table;
1518 hi = fence = (tab == null) ? 0 : tab.length;
1519 }
1520 return hi;
1521 }
1522
1523 public final long estimateSize() {
1524 getFence(); // force init
1525 return (long) est;
1526 }
1527 }
1528
1529 static final class KeySpliterator<K,V>
1530 extends HashMapSpliterator<K,V>
1531 implements Spliterator<K> {
1532 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1533 int expectedModCount) {
1534 super(m, origin, fence, est, expectedModCount);
1535 }
1536
1537 public KeySpliterator<K,V> trySplit() {
1538 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1539 return (lo >= mid || current != null) ? null :
1540 new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1541 expectedModCount);
1542 }
1543
1544 public void forEachRemaining(Consumer<? super K> action) {
1545 int i, hi, mc;
1546 if (action == null)
1547 throw new NullPointerException();
1548 HashMap<K,V> m = map;
1549 Node<K,V>[] tab = m.table;
1550 if ((hi = fence) < 0) {
1551 mc = expectedModCount = m.modCount;
1552 hi = fence = (tab == null) ? 0 : tab.length;
1553 }
1554 else
1555 mc = expectedModCount;
1556 if (tab != null && tab.length >= hi &&
1557 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1558 Node<K,V> p = current;
1559 current = null;
1560 do {
1561 if (p == null)
1562 p = tab[i++];
1563 else {
1564 action.accept(p.key);
1565 p = p.next;
1566 }
1567 } while (p != null || i < hi);
1568 if (m.modCount != mc)
1569 throw new ConcurrentModificationException();
1570 }
1571 }
1572
1573 public boolean tryAdvance(Consumer<? super K> action) {
1574 int hi;
1575 if (action == null)
1576 throw new NullPointerException();
1577 Node<K,V>[] tab = map.table;
1578 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1579 while (current != null || index < hi) {
1580 if (current == null)
1581 current = tab[index++];
1582 else {
1583 K k = current.key;
1584 current = current.next;
1585 action.accept(k);
1586 if (map.modCount != expectedModCount)
1587 throw new ConcurrentModificationException();
1588 return true;
1589 }
1590 }
1591 }
1592 return false;
1593 }
1594
1595 public int characteristics() {
1596 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1597 Spliterator.DISTINCT;
1598 }
1599 }
1600
1601 static final class ValueSpliterator<K,V>
1602 extends HashMapSpliterator<K,V>
1603 implements Spliterator<V> {
1604 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1605 int expectedModCount) {
1606 super(m, origin, fence, est, expectedModCount);
1607 }
1608
1609 public ValueSpliterator<K,V> trySplit() {
1610 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1611 return (lo >= mid || current != null) ? null :
1612 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1613 expectedModCount);
1614 }
1615
1616 public void forEachRemaining(Consumer<? super V> action) {
1617 int i, hi, mc;
1618 if (action == null)
1619 throw new NullPointerException();
1620 HashMap<K,V> m = map;
1621 Node<K,V>[] tab = m.table;
1622 if ((hi = fence) < 0) {
1623 mc = expectedModCount = m.modCount;
1624 hi = fence = (tab == null) ? 0 : tab.length;
1625 }
1626 else
1627 mc = expectedModCount;
1628 if (tab != null && tab.length >= hi &&
1629 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1630 Node<K,V> p = current;
1631 current = null;
1632 do {
1633 if (p == null)
1634 p = tab[i++];
1635 else {
1636 action.accept(p.value);
1637 p = p.next;
1638 }
1639 } while (p != null || i < hi);
1640 if (m.modCount != mc)
1641 throw new ConcurrentModificationException();
1642 }
1643 }
1644
1645 public boolean tryAdvance(Consumer<? super V> action) {
1646 int hi;
1647 if (action == null)
1648 throw new NullPointerException();
1649 Node<K,V>[] tab = map.table;
1650 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1651 while (current != null || index < hi) {
1652 if (current == null)
1653 current = tab[index++];
1654 else {
1655 V v = current.value;
1656 current = current.next;
1657 action.accept(v);
1658 if (map.modCount != expectedModCount)
1659 throw new ConcurrentModificationException();
1660 return true;
1661 }
1662 }
1663 }
1664 return false;
1665 }
1666
1667 public int characteristics() {
1668 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1669 }
1670 }
1671
1672 static final class EntrySpliterator<K,V>
1673 extends HashMapSpliterator<K,V>
1674 implements Spliterator<Map.Entry<K,V>> {
1675 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1676 int expectedModCount) {
1677 super(m, origin, fence, est, expectedModCount);
1678 }
1679
1680 public EntrySpliterator<K,V> trySplit() {
1681 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1682 return (lo >= mid || current != null) ? null :
1683 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1684 expectedModCount);
1685 }
1686
1687 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1688 int i, hi, mc;
1689 if (action == null)
1690 throw new NullPointerException();
1691 HashMap<K,V> m = map;
1692 Node<K,V>[] tab = m.table;
1693 if ((hi = fence) < 0) {
1694 mc = expectedModCount = m.modCount;
1695 hi = fence = (tab == null) ? 0 : tab.length;
1696 }
1697 else
1698 mc = expectedModCount;
1699 if (tab != null && tab.length >= hi &&
1700 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1701 Node<K,V> p = current;
1702 current = null;
1703 do {
1704 if (p == null)
1705 p = tab[i++];
1706 else {
1707 action.accept(p);
1708 p = p.next;
1709 }
1710 } while (p != null || i < hi);
1711 if (m.modCount != mc)
1712 throw new ConcurrentModificationException();
1713 }
1714 }
1715
1716 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1717 int hi;
1718 if (action == null)
1719 throw new NullPointerException();
1720 Node<K,V>[] tab = map.table;
1721 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1722 while (current != null || index < hi) {
1723 if (current == null)
1724 current = tab[index++];
1725 else {
1726 Node<K,V> e = current;
1727 current = current.next;
1728 action.accept(e);
1729 if (map.modCount != expectedModCount)
1730 throw new ConcurrentModificationException();
1731 return true;
1732 }
1733 }
1734 }
1735 return false;
1736 }
1737
1738 public int characteristics() {
1739 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1740 Spliterator.DISTINCT;
1741 }
1742 }
1743
1744 /* ------------------------------------------------------------ */
1745 // LinkedHashMap support
1746
1747
1748 /*
1749 * The following package-protected methods are designed to be
1750 * overridden by LinkedHashMap, but not by any other subclass.
1751 * Nearly all other internal methods are also package-protected
1752 * but are declared final, so can be used by LinkedHashMap, view
1753 * classes, and HashSet.
1754 */
1755
1756 // Create a regular (non-tree) node
1757 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1758 return new Node<>(hash, key, value, next);
1759 }
1760
1761 // For conversion from TreeNodes to plain nodes
1762 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1763 return new Node<>(p.hash, p.key, p.value, next);
1764 }
1765
1766 // Create a tree bin node
1767 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1768 return new TreeNode<>(hash, key, value, next);
1769 }
1770
1771 // For treeifyBin
1772 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1773 return new TreeNode<>(p.hash, p.key, p.value, next);
1774 }
1775
1776 /**
1777 * Reset to initial default state. Called by clone and readObject.
1778 */
1779 void reinitialize() {
1780 table = null;
1781 entrySet = null;
1782 keySet = null;
1783 values = null;
1784 modCount = 0;
1785 threshold = 0;
1786 size = 0;
1787 }
1788
1789 // Callbacks to allow LinkedHashMap post-actions
1790 void afterNodeAccess(Node<K,V> p) { }
1791 void afterNodeInsertion(boolean evict) { }
1792 void afterNodeRemoval(Node<K,V> p) { }
1793
1794 // Called only from writeObject, to ensure compatible ordering.
1795 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1796 Node<K,V>[] tab;
1797 if (size > 0 && (tab = table) != null) {
1798 for (Node<K, V> e : tab) {
1799 for (; e != null; e = e.next) {
1800 s.writeObject(e.key);
1801 s.writeObject(e.value);
1802 }
1803 }
1804 }
1805 }
1806
1807 /* ------------------------------------------------------------ */
1808 // Tree bins
1809
1810 /**
1811 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1812 * extends Node) so can be used as extension of either regular or
1813 * linked node.
1814 */
1815 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1816 TreeNode<K,V> parent; // red-black tree links
1817 TreeNode<K,V> left;
1818 TreeNode<K,V> right;
1819 TreeNode<K,V> prev; // needed to unlink next upon deletion
1820 boolean red;
1821 TreeNode(int hash, K key, V val, Node<K,V> next) {
1822 super(hash, key, val, next);
1823 }
1824
1825 /**
1826 * Returns root of tree containing this node.
1827 */
1828 final TreeNode<K,V> root() {
1829 for (TreeNode<K,V> r = this, p;;) {
1830 if ((p = r.parent) == null)
1831 return r;
1832 r = p;
1833 }
1834 }
1835
1836 /**
1837 * Ensures that the given root is the first node of its bin.
1838 */
1839 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1840 int n;
1841 if (root != null && tab != null && (n = tab.length) > 0) {
1842 int index = (n - 1) & root.hash;
1843 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1844 if (root != first) {
1845 Node<K,V> rn;
1846 tab[index] = root;
1847 TreeNode<K,V> rp = root.prev;
1848 if ((rn = root.next) != null)
1849 ((TreeNode<K,V>)rn).prev = rp;
1850 if (rp != null)
1851 rp.next = rn;
1852 if (first != null)
1853 first.prev = root;
1854 root.next = first;
1855 root.prev = null;
1856 }
1857 assert checkInvariants(root);
1858 }
1859 }
1860
1861 /**
1862 * Finds the node starting at root p with the given hash and key.
1863 * The kc argument caches comparableClassFor(key) upon first use
1864 * comparing keys.
1865 */
1866 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1867 TreeNode<K,V> p = this;
1868 do {
1869 int ph, dir; K pk;
1870 TreeNode<K,V> pl = p.left, pr = p.right, q;
1871 if ((ph = p.hash) > h)
1872 p = pl;
1873 else if (ph < h)
1874 p = pr;
1875 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1876 return p;
1877 else if (pl == null)
1878 p = pr;
1879 else if (pr == null)
1880 p = pl;
1881 else if ((kc != null ||
1882 (kc = comparableClassFor(k)) != null) &&
1883 (dir = compareComparables(kc, k, pk)) != 0)
1884 p = (dir < 0) ? pl : pr;
1885 else if ((q = pr.find(h, k, kc)) != null)
1886 return q;
1887 else
1888 p = pl;
1889 } while (p != null);
1890 return null;
1891 }
1892
1893 /**
1894 * Calls find for root node.
1895 */
1896 final TreeNode<K,V> getTreeNode(int h, Object k) {
1897 return ((parent != null) ? root() : this).find(h, k, null);
1898 }
1899
1900 /**
1901 * Tie-breaking utility for ordering insertions when equal
1902 * hashCodes and non-comparable. We don't require a total
1903 * order, just a consistent insertion rule to maintain
1904 * equivalence across rebalancings. Tie-breaking further than
1905 * necessary simplifies testing a bit.
1906 */
1907 static int tieBreakOrder(Object a, Object b) {
1908 int d;
1909 if (a == null || b == null ||
1910 (d = a.getClass().getName().
1911 compareTo(b.getClass().getName())) == 0)
1912 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
1913 -1 : 1);
1914 return d;
1915 }
1916
1917 /**
1918 * Forms tree of the nodes linked from this node.
1919 * @return root of tree
1920 */
1921 final void treeify(Node<K,V>[] tab) {
1922 TreeNode<K,V> root = null;
1923 for (TreeNode<K,V> x = this, next; x != null; x = next) {
1924 next = (TreeNode<K,V>)x.next;
1925 x.left = x.right = null;
1926 if (root == null) {
1927 x.parent = null;
1928 x.red = false;
1929 root = x;
1930 }
1931 else {
1932 K k = x.key;
1933 int h = x.hash;
1934 Class<?> kc = null;
1935 for (TreeNode<K,V> p = root;;) {
1936 int dir, ph;
1937 K pk = p.key;
1938 if ((ph = p.hash) > h)
1939 dir = -1;
1940 else if (ph < h)
1941 dir = 1;
1942 else if ((kc == null &&
1943 (kc = comparableClassFor(k)) == null) ||
1944 (dir = compareComparables(kc, k, pk)) == 0)
1945 dir = tieBreakOrder(k, pk);
1946
1947 TreeNode<K,V> xp = p;
1948 if ((p = (dir <= 0) ? p.left : p.right) == null) {
1949 x.parent = xp;
1950 if (dir <= 0)
1951 xp.left = x;
1952 else
1953 xp.right = x;
1954 root = balanceInsertion(root, x);
1955 break;
1956 }
1957 }
1958 }
1959 }
1960 moveRootToFront(tab, root);
1961 }
1962
1963 /**
1964 * Returns a list of non-TreeNodes replacing those linked from
1965 * this node.
1966 */
1967 final Node<K,V> untreeify(HashMap<K,V> map) {
1968 Node<K,V> hd = null, tl = null;
1969 for (Node<K,V> q = this; q != null; q = q.next) {
1970 Node<K,V> p = map.replacementNode(q, null);
1971 if (tl == null)
1972 hd = p;
1973 else
1974 tl.next = p;
1975 tl = p;
1976 }
1977 return hd;
1978 }
1979
1980 /**
1981 * Tree version of putVal.
1982 */
1983 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
1984 int h, K k, V v) {
1985 Class<?> kc = null;
1986 boolean searched = false;
1987 TreeNode<K,V> root = (parent != null) ? root() : this;
1988 for (TreeNode<K,V> p = root;;) {
1989 int dir, ph; K pk;
1990 if ((ph = p.hash) > h)
1991 dir = -1;
1992 else if (ph < h)
1993 dir = 1;
1994 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
1995 return p;
1996 else if ((kc == null &&
1997 (kc = comparableClassFor(k)) == null) ||
1998 (dir = compareComparables(kc, k, pk)) == 0) {
1999 if (!searched) {
2000 TreeNode<K,V> q, ch;
2001 searched = true;
2002 if (((ch = p.left) != null &&
2003 (q = ch.find(h, k, kc)) != null) ||
2004 ((ch = p.right) != null &&
2005 (q = ch.find(h, k, kc)) != null))
2006 return q;
2007 }
2008 dir = tieBreakOrder(k, pk);
2009 }
2010
2011 TreeNode<K,V> xp = p;
2012 if ((p = (dir <= 0) ? p.left : p.right) == null) {
2013 Node<K,V> xpn = xp.next;
2014 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
2015 if (dir <= 0)
2016 xp.left = x;
2017 else
2018 xp.right = x;
2019 xp.next = x;
2020 x.parent = x.prev = xp;
2021 if (xpn != null)
2022 ((TreeNode<K,V>)xpn).prev = x;
2023 moveRootToFront(tab, balanceInsertion(root, x));
2024 return null;
2025 }
2026 }
2027 }
2028
2029 /**
2030 * Removes the given node, that must be present before this call.
2031 * This is messier than typical red-black deletion code because we
2032 * cannot swap the contents of an interior node with a leaf
2033 * successor that is pinned by "next" pointers that are accessible
2034 * independently during traversal. So instead we swap the tree
2035 * linkages. If the current tree appears to have too few nodes,
2036 * the bin is converted back to a plain bin. (The test triggers
2037 * somewhere between 2 and 6 nodes, depending on tree structure).
2038 */
2039 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2040 boolean movable) {
2041 int n;
2042 if (tab == null || (n = tab.length) == 0)
2043 return;
2044 int index = (n - 1) & hash;
2045 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2046 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2047 if (pred == null)
2048 tab[index] = first = succ;
2049 else
2050 pred.next = succ;
2051 if (succ != null)
2052 succ.prev = pred;
2053 if (first == null)
2054 return;
2055 if (root.parent != null)
2056 root = root.root();
2057 if (root == null || root.right == null ||
2058 (rl = root.left) == null || rl.left == null) {
2059 tab[index] = first.untreeify(map); // too small
2060 return;
2061 }
2062 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2063 if (pl != null && pr != null) {
2064 TreeNode<K,V> s = pr, sl;
2065 while ((sl = s.left) != null) // find successor
2066 s = sl;
2067 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2068 TreeNode<K,V> sr = s.right;
2069 TreeNode<K,V> pp = p.parent;
2070 if (s == pr) { // p was s's direct parent
2071 p.parent = s;
2072 s.right = p;
2073 }
2074 else {
2075 TreeNode<K,V> sp = s.parent;
2076 if ((p.parent = sp) != null) {
2077 if (s == sp.left)
2078 sp.left = p;
2079 else
2080 sp.right = p;
2081 }
2082 if ((s.right = pr) != null)
2083 pr.parent = s;
2084 }
2085 p.left = null;
2086 if ((p.right = sr) != null)
2087 sr.parent = p;
2088 if ((s.left = pl) != null)
2089 pl.parent = s;
2090 if ((s.parent = pp) == null)
2091 root = s;
2092 else if (p == pp.left)
2093 pp.left = s;
2094 else
2095 pp.right = s;
2096 if (sr != null)
2097 replacement = sr;
2098 else
2099 replacement = p;
2100 }
2101 else if (pl != null)
2102 replacement = pl;
2103 else if (pr != null)
2104 replacement = pr;
2105 else
2106 replacement = p;
2107 if (replacement != p) {
2108 TreeNode<K,V> pp = replacement.parent = p.parent;
2109 if (pp == null)
2110 root = replacement;
2111 else if (p == pp.left)
2112 pp.left = replacement;
2113 else
2114 pp.right = replacement;
2115 p.left = p.right = p.parent = null;
2116 }
2117
2118 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2119
2120 if (replacement == p) { // detach
2121 TreeNode<K,V> pp = p.parent;
2122 p.parent = null;
2123 if (pp != null) {
2124 if (p == pp.left)
2125 pp.left = null;
2126 else if (p == pp.right)
2127 pp.right = null;
2128 }
2129 }
2130 if (movable)
2131 moveRootToFront(tab, r);
2132 }
2133
2134 /**
2135 * Splits nodes in a tree bin into lower and upper tree bins,
2136 * or untreeifies if now too small. Called only from resize;
2137 * see above discussion about split bits and indices.
2138 *
2139 * @param map the map
2140 * @param tab the table for recording bin heads
2141 * @param index the index of the table being split
2142 * @param bit the bit of hash to split on
2143 */
2144 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2145 TreeNode<K,V> b = this;
2146 // Relink into lo and hi lists, preserving order
2147 TreeNode<K,V> loHead = null, loTail = null;
2148 TreeNode<K,V> hiHead = null, hiTail = null;
2149 int lc = 0, hc = 0;
2150 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2151 next = (TreeNode<K,V>)e.next;
2152 e.next = null;
2153 if ((e.hash & bit) == 0) {
2154 if ((e.prev = loTail) == null)
2155 loHead = e;
2156 else
2157 loTail.next = e;
2158 loTail = e;
2159 ++lc;
2160 }
2161 else {
2162 if ((e.prev = hiTail) == null)
2163 hiHead = e;
2164 else
2165 hiTail.next = e;
2166 hiTail = e;
2167 ++hc;
2168 }
2169 }
2170
2171 if (loHead != null) {
2172 if (lc <= UNTREEIFY_THRESHOLD)
2173 tab[index] = loHead.untreeify(map);
2174 else {
2175 tab[index] = loHead;
2176 if (hiHead != null) // (else is already treeified)
2177 loHead.treeify(tab);
2178 }
2179 }
2180 if (hiHead != null) {
2181 if (hc <= UNTREEIFY_THRESHOLD)
2182 tab[index + bit] = hiHead.untreeify(map);
2183 else {
2184 tab[index + bit] = hiHead;
2185 if (loHead != null)
2186 hiHead.treeify(tab);
2187 }
2188 }
2189 }
2190
2191 /* ------------------------------------------------------------ */
2192 // Red-black tree methods, all adapted from CLR
2193
2194 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2195 TreeNode<K,V> p) {
2196 TreeNode<K,V> r, pp, rl;
2197 if (p != null && (r = p.right) != null) {
2198 if ((rl = p.right = r.left) != null)
2199 rl.parent = p;
2200 if ((pp = r.parent = p.parent) == null)
2201 (root = r).red = false;
2202 else if (pp.left == p)
2203 pp.left = r;
2204 else
2205 pp.right = r;
2206 r.left = p;
2207 p.parent = r;
2208 }
2209 return root;
2210 }
2211
2212 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2213 TreeNode<K,V> p) {
2214 TreeNode<K,V> l, pp, lr;
2215 if (p != null && (l = p.left) != null) {
2216 if ((lr = p.left = l.right) != null)
2217 lr.parent = p;
2218 if ((pp = l.parent = p.parent) == null)
2219 (root = l).red = false;
2220 else if (pp.right == p)
2221 pp.right = l;
2222 else
2223 pp.left = l;
2224 l.right = p;
2225 p.parent = l;
2226 }
2227 return root;
2228 }
2229
2230 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2231 TreeNode<K,V> x) {
2232 x.red = true;
2233 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2234 if ((xp = x.parent) == null) {
2235 x.red = false;
2236 return x;
2237 }
2238 else if (!xp.red || (xpp = xp.parent) == null)
2239 return root;
2240 if (xp == (xppl = xpp.left)) {
2241 if ((xppr = xpp.right) != null && xppr.red) {
2242 xppr.red = false;
2243 xp.red = false;
2244 xpp.red = true;
2245 x = xpp;
2246 }
2247 else {
2248 if (x == xp.right) {
2249 root = rotateLeft(root, x = xp);
2250 xpp = (xp = x.parent) == null ? null : xp.parent;
2251 }
2252 if (xp != null) {
2253 xp.red = false;
2254 if (xpp != null) {
2255 xpp.red = true;
2256 root = rotateRight(root, xpp);
2257 }
2258 }
2259 }
2260 }
2261 else {
2262 if (xppl != null && xppl.red) {
2263 xppl.red = false;
2264 xp.red = false;
2265 xpp.red = true;
2266 x = xpp;
2267 }
2268 else {
2269 if (x == xp.left) {
2270 root = rotateRight(root, x = xp);
2271 xpp = (xp = x.parent) == null ? null : xp.parent;
2272 }
2273 if (xp != null) {
2274 xp.red = false;
2275 if (xpp != null) {
2276 xpp.red = true;
2277 root = rotateLeft(root, xpp);
2278 }
2279 }
2280 }
2281 }
2282 }
2283 }
2284
2285 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2286 TreeNode<K,V> x) {
2287 for (TreeNode<K,V> xp, xpl, xpr;;) {
2288 if (x == null || x == root)
2289 return root;
2290 else if ((xp = x.parent) == null) {
2291 x.red = false;
2292 return x;
2293 }
2294 else if (x.red) {
2295 x.red = false;
2296 return root;
2297 }
2298 else if ((xpl = xp.left) == x) {
2299 if ((xpr = xp.right) != null && xpr.red) {
2300 xpr.red = false;
2301 xp.red = true;
2302 root = rotateLeft(root, xp);
2303 xpr = (xp = x.parent) == null ? null : xp.right;
2304 }
2305 if (xpr == null)
2306 x = xp;
2307 else {
2308 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2309 if ((sr == null || !sr.red) &&
2310 (sl == null || !sl.red)) {
2311 xpr.red = true;
2312 x = xp;
2313 }
2314 else {
2315 if (sr == null || !sr.red) {
2316 if (sl != null)
2317 sl.red = false;
2318 xpr.red = true;
2319 root = rotateRight(root, xpr);
2320 xpr = (xp = x.parent) == null ?
2321 null : xp.right;
2322 }
2323 if (xpr != null) {
2324 xpr.red = (xp == null) ? false : xp.red;
2325 if ((sr = xpr.right) != null)
2326 sr.red = false;
2327 }
2328 if (xp != null) {
2329 xp.red = false;
2330 root = rotateLeft(root, xp);
2331 }
2332 x = root;
2333 }
2334 }
2335 }
2336 else { // symmetric
2337 if (xpl != null && xpl.red) {
2338 xpl.red = false;
2339 xp.red = true;
2340 root = rotateRight(root, xp);
2341 xpl = (xp = x.parent) == null ? null : xp.left;
2342 }
2343 if (xpl == null)
2344 x = xp;
2345 else {
2346 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2347 if ((sl == null || !sl.red) &&
2348 (sr == null || !sr.red)) {
2349 xpl.red = true;
2350 x = xp;
2351 }
2352 else {
2353 if (sl == null || !sl.red) {
2354 if (sr != null)
2355 sr.red = false;
2356 xpl.red = true;
2357 root = rotateLeft(root, xpl);
2358 xpl = (xp = x.parent) == null ?
2359 null : xp.left;
2360 }
2361 if (xpl != null) {
2362 xpl.red = (xp == null) ? false : xp.red;
2363 if ((sl = xpl.left) != null)
2364 sl.red = false;
2365 }
2366 if (xp != null) {
2367 xp.red = false;
2368 root = rotateRight(root, xp);
2369 }
2370 x = root;
2371 }
2372 }
2373 }
2374 }
2375 }
2376
2377 /**
2378 * Recursive invariant check
2379 */
2380 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2381 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2382 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2383 if (tb != null && tb.next != t)
2384 return false;
2385 if (tn != null && tn.prev != t)
2386 return false;
2387 if (tp != null && t != tp.left && t != tp.right)
2388 return false;
2389 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2390 return false;
2391 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2392 return false;
2393 if (t.red && tl != null && tl.red && tr != null && tr.red)
2394 return false;
2395 if (tl != null && !checkInvariants(tl))
2396 return false;
2397 if (tr != null && !checkInvariants(tr))
2398 return false;
2399 return true;
2400 }
2401 }
2402
2403 }