1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.util; 27 28 import java.io.IOException; 29 import java.io.InvalidObjectException; 30 import java.io.Serializable; 31 import java.lang.reflect.ParameterizedType; 32 import java.lang.reflect.Type; 33 import java.util.function.BiConsumer; 34 import java.util.function.BiFunction; 35 import java.util.function.Consumer; 36 import java.util.function.Function; 37 38 /** 39 * Hash table based implementation of the <tt>Map</tt> interface. This 40 * implementation provides all of the optional map operations, and permits 41 * <tt>null</tt> values and the <tt>null</tt> key. (The <tt>HashMap</tt> 42 * class is roughly equivalent to <tt>Hashtable</tt>, except that it is 43 * unsynchronized and permits nulls.) This class makes no guarantees as to 44 * the order of the map; in particular, it does not guarantee that the order 45 * will remain constant over time. 46 * 47 * <p>This implementation provides constant-time performance for the basic 48 * operations (<tt>get</tt> and <tt>put</tt>), assuming the hash function 49 * disperses the elements properly among the buckets. Iteration over 50 * collection views requires time proportional to the "capacity" of the 51 * <tt>HashMap</tt> instance (the number of buckets) plus its size (the number 52 * of key-value mappings). Thus, it's very important not to set the initial 53 * capacity too high (or the load factor too low) if iteration performance is 54 * important. 55 * 56 * <p>An instance of <tt>HashMap</tt> has two parameters that affect its 57 * performance: <i>initial capacity</i> and <i>load factor</i>. The 58 * <i>capacity</i> is the number of buckets in the hash table, and the initial 59 * capacity is simply the capacity at the time the hash table is created. The 60 * <i>load factor</i> is a measure of how full the hash table is allowed to 61 * get before its capacity is automatically increased. When the number of 62 * entries in the hash table exceeds the product of the load factor and the 63 * current capacity, the hash table is <i>rehashed</i> (that is, internal data 64 * structures are rebuilt) so that the hash table has approximately twice the 65 * number of buckets. 66 * 67 * <p>As a general rule, the default load factor (.75) offers a good 68 * tradeoff between time and space costs. Higher values decrease the 69 * space overhead but increase the lookup cost (reflected in most of 70 * the operations of the <tt>HashMap</tt> class, including 71 * <tt>get</tt> and <tt>put</tt>). The expected number of entries in 72 * the map and its load factor should be taken into account when 73 * setting its initial capacity, so as to minimize the number of 74 * rehash operations. If the initial capacity is greater than the 75 * maximum number of entries divided by the load factor, no rehash 76 * operations will ever occur. 77 * 78 * <p>If many mappings are to be stored in a <tt>HashMap</tt> 79 * instance, creating it with a sufficiently large capacity will allow 80 * the mappings to be stored more efficiently than letting it perform 81 * automatic rehashing as needed to grow the table. Note that using 82 * many keys with the same {@code hashCode()} is a sure way to slow 83 * down performance of any hash table. To ameliorate impact, when keys 84 * are {@link Comparable}, this class may use comparison order among 85 * keys to help break ties. 86 * 87 * <p><strong>Note that this implementation is not synchronized.</strong> 88 * If multiple threads access a hash map concurrently, and at least one of 89 * the threads modifies the map structurally, it <i>must</i> be 90 * synchronized externally. (A structural modification is any operation 91 * that adds or deletes one or more mappings; merely changing the value 92 * associated with a key that an instance already contains is not a 93 * structural modification.) This is typically accomplished by 94 * synchronizing on some object that naturally encapsulates the map. 95 * 96 * If no such object exists, the map should be "wrapped" using the 97 * {@link Collections#synchronizedMap Collections.synchronizedMap} 98 * method. This is best done at creation time, to prevent accidental 99 * unsynchronized access to the map:<pre> 100 * Map m = Collections.synchronizedMap(new HashMap(...));</pre> 101 * 102 * <p>The iterators returned by all of this class's "collection view methods" 103 * are <i>fail-fast</i>: if the map is structurally modified at any time after 104 * the iterator is created, in any way except through the iterator's own 105 * <tt>remove</tt> method, the iterator will throw a 106 * {@link ConcurrentModificationException}. Thus, in the face of concurrent 107 * modification, the iterator fails quickly and cleanly, rather than risking 108 * arbitrary, non-deterministic behavior at an undetermined time in the 109 * future. 110 * 111 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed 112 * as it is, generally speaking, impossible to make any hard guarantees in the 113 * presence of unsynchronized concurrent modification. Fail-fast iterators 114 * throw <tt>ConcurrentModificationException</tt> on a best-effort basis. 115 * Therefore, it would be wrong to write a program that depended on this 116 * exception for its correctness: <i>the fail-fast behavior of iterators 117 * should be used only to detect bugs.</i> 118 * 119 * <p>This class is a member of the 120 * <a href="{@docRoot}/../technotes/guides/collections/index.html"> 121 * Java Collections Framework</a>. 122 * 123 * @param <K> the type of keys maintained by this map 124 * @param <V> the type of mapped values 125 * 126 * @author Doug Lea 127 * @author Josh Bloch 128 * @author Arthur van Hoff 129 * @author Neal Gafter 130 * @see Object#hashCode() 131 * @see Collection 132 * @see Map 133 * @see TreeMap 134 * @see Hashtable 135 * @since 1.2 136 */ 137 public class HashMap<K,V> extends AbstractMap<K,V> 138 implements Map<K,V>, Cloneable, Serializable { 139 140 private static final long serialVersionUID = 362498820763181265L; 141 142 /* 143 * Implementation notes. 144 * 145 * This map usually acts as a binned (bucketed) hash table, but 146 * when bins get too large, they are transformed into bins of 147 * TreeNodes, each structured similarly to those in 148 * java.util.TreeMap. Most methods try to use normal bins, but 149 * relay to TreeNode methods when applicable (simply by checking 150 * instanceof a node). Bins of TreeNodes may be traversed and 151 * used like any others, but additionally support faster lookup 152 * when overpopulated. However, since the vast majority of bins in 153 * normal use are not overpopulated, checking for existence of 154 * tree bins may be delayed in the course of table methods. 155 * 156 * Tree bins (i.e., bins whose elements are all TreeNodes) are 157 * ordered primarily by hashCode, but in the case of ties, if two 158 * elements are of the same "class C implements Comparable<C>", 159 * type then their compareTo method is used for ordering. (We 160 * conservatively check generic types via reflection to validate 161 * this -- see method comparableClassFor). The added complexity 162 * of tree bins is worthwhile in providing worst-case O(log n) 163 * operations when keys either have distinct hashes or are 164 * orderable, Thus, performance degrades gracefully under 165 * accidental or malicious usages in which hashCode() methods 166 * return values that are poorly distributed, as well as those in 167 * which many keys share a hashCode, so long as they are also 168 * Comparable. (If neither of these apply, we may waste about a 169 * factor of two in time and space compared to taking no 170 * precautions. But the only known cases stem from poor user 171 * programming practices that are already so slow that this makes 172 * little difference.) 173 * 174 * Because TreeNodes are about twice the size of regular nodes, we 175 * use them only when bins contain enough nodes to warrant use 176 * (see TREEIFY_THRESHOLD). And when they become too small (due to 177 * removal or resizing) they are converted back to plain bins. In 178 * usages with well-distributed user hashCodes, tree bins are 179 * rarely used. Ideally, under random hashCodes, the frequency of 180 * nodes in bins follows a Poisson distribution 181 * (http://en.wikipedia.org/wiki/Poisson_distribution) with a 182 * parameter of about 0.5 on average for the default resizing 183 * threshold of 0.75, although with a large variance because of 184 * resizing granularity. Ignoring variance, the expected 185 * occurrences of list size k are (exp(-0.5) * pow(0.5, k) / 186 * factorial(k)). The first values are: 187 * 188 * 0: 0.60653066 189 * 1: 0.30326533 190 * 2: 0.07581633 191 * 3: 0.01263606 192 * 4: 0.00157952 193 * 5: 0.00015795 194 * 6: 0.00001316 195 * 7: 0.00000094 196 * 8: 0.00000006 197 * more: less than 1 in ten million 198 * 199 * The root of a tree bin is normally its first node. However, 200 * sometimes (currently only upon Iterator.remove), the root might 201 * be elsewhere, but can be recovered following parent links 202 * (method TreeNode.root()). 203 * 204 * All applicable internal methods accept a hash code as an 205 * argument (as normally supplied from a public method), allowing 206 * them to call each other without recomputing user hashCodes. 207 * Most internal methods also accept a "tab" argument, that is 208 * normally the current table, but may be a new or old one when 209 * resizing or converting. 210 * 211 * When bin lists are treeified, split, or untreeified, we keep 212 * them in the same relative access/traversal order (i.e., field 213 * Node.next) to better preserve locality, and to slightly 214 * simplify handling of splits and traversals that invoke 215 * iterator.remove. When using comparators on insertion, to keep a 216 * total ordering (or as close as is required here) across 217 * rebalancings, we compare classes and identityHashCodes as 218 * tie-breakers. 219 * 220 * The use and transitions among plain vs tree modes is 221 * complicated by the existence of subclass LinkedHashMap. See 222 * below for hook methods defined to be invoked upon insertion, 223 * removal and access that allow LinkedHashMap internals to 224 * otherwise remain independent of these mechanics. (This also 225 * requires that a map instance be passed to some utility methods 226 * that may create new nodes.) 227 * 228 * The concurrent-programming-like SSA-based coding style helps 229 * avoid aliasing errors amid all of the twisty pointer operations. 230 */ 231 232 /** 233 * The default initial capacity - MUST be a power of two. 234 */ 235 static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16 236 237 /** 238 * The maximum capacity, used if a higher value is implicitly specified 239 * by either of the constructors with arguments. 240 * MUST be a power of two <= 1<<30. 241 */ 242 static final int MAXIMUM_CAPACITY = 1 << 30; 243 244 /** 245 * The load factor used when none specified in constructor. 246 */ 247 static final float DEFAULT_LOAD_FACTOR = 0.75f; 248 249 /** 250 * The bin count threshold for using a tree rather than list for a 251 * bin. Bins are converted to trees when adding an element to a 252 * bin with at least this many nodes. The value must be greater 253 * than 2 and should be at least 8 to mesh with assumptions in 254 * tree removal about conversion back to plain bins upon 255 * shrinkage. 256 */ 257 static final int TREEIFY_THRESHOLD = 8; 258 259 /** 260 * The bin count threshold for untreeifying a (split) bin during a 261 * resize operation. Should be less than TREEIFY_THRESHOLD, and at 262 * most 6 to mesh with shrinkage detection under removal. 263 */ 264 static final int UNTREEIFY_THRESHOLD = 6; 265 266 /** 267 * The smallest table capacity for which bins may be treeified. 268 * (Otherwise the table is resized if too many nodes in a bin.) 269 * Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts 270 * between resizing and treeification thresholds. 271 */ 272 static final int MIN_TREEIFY_CAPACITY = 64; 273 274 /** 275 * Basic hash bin node, used for most entries. (See below for 276 * TreeNode subclass, and in LinkedHashMap for its Entry subclass.) 277 */ 278 static class Node<K,V> implements Map.Entry<K,V> { 279 final int hash; 280 final K key; 281 V value; 282 Node<K,V> next; 283 284 Node(int hash, K key, V value, Node<K,V> next) { 285 this.hash = hash; 286 this.key = key; 287 this.value = value; 288 this.next = next; 289 } 290 291 public final K getKey() { return key; } 292 public final V getValue() { return value; } 293 public final String toString() { return key + "=" + value; } 294 295 public final int hashCode() { 296 return Objects.hashCode(key) ^ Objects.hashCode(value); 297 } 298 299 public final V setValue(V newValue) { 300 V oldValue = value; 301 value = newValue; 302 return oldValue; 303 } 304 305 public final boolean equals(Object o) { 306 if (o == this) 307 return true; 308 if (o instanceof Map.Entry) { 309 Map.Entry<?,?> e = (Map.Entry<?,?>)o; 310 if (Objects.equals(key, e.getKey()) && 311 Objects.equals(value, e.getValue())) 312 return true; 313 } 314 return false; 315 } 316 } 317 318 /* ---------------- Static utilities -------------- */ 319 320 /** 321 * Computes key.hashCode() and spreads (XORs) higher bits of hash 322 * to lower. Because the table uses power-of-two masking, sets of 323 * hashes that vary only in bits above the current mask will 324 * always collide. (Among known examples are sets of Float keys 325 * holding consecutive whole numbers in small tables.) So we 326 * apply a transform that spreads the impact of higher bits 327 * downward. There is a tradeoff between speed, utility, and 328 * quality of bit-spreading. Because many common sets of hashes 329 * are already reasonably distributed (so don't benefit from 330 * spreading), and because we use trees to handle large sets of 331 * collisions in bins, we just XOR some shifted bits in the 332 * cheapest possible way to reduce systematic lossage, as well as 333 * to incorporate impact of the highest bits that would otherwise 334 * never be used in index calculations because of table bounds. 335 */ 336 static final int hash(Object key) { 337 int h; 338 return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16); 339 } 340 341 /** 342 * Returns x's Class if it is of the form "class C implements 343 * Comparable<C>", else null. 344 */ 345 static Class<?> comparableClassFor(Object x) { 346 if (x instanceof Comparable) { 347 Class<?> c; Type[] ts, as; Type t; ParameterizedType p; 348 if ((c = x.getClass()) == String.class) // bypass checks 349 return c; 350 if ((ts = c.getGenericInterfaces()) != null) { 351 for (int i = 0; i < ts.length; ++i) { 352 if (((t = ts[i]) instanceof ParameterizedType) && 353 ((p = (ParameterizedType)t).getRawType() == 354 Comparable.class) && 355 (as = p.getActualTypeArguments()) != null && 356 as.length == 1 && as[0] == c) // type arg is c 357 return c; 358 } 359 } 360 } 361 return null; 362 } 363 364 /** 365 * Returns k.compareTo(x) if x matches kc (k's screened comparable 366 * class), else 0. 367 */ 368 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable 369 static int compareComparables(Class<?> kc, Object k, Object x) { 370 return (x == null || x.getClass() != kc ? 0 : 371 ((Comparable)k).compareTo(x)); 372 } 373 374 /** 375 * Returns a power of two size for the given target capacity. 376 */ 377 static final int tableSizeFor(int cap) { 378 int n = cap - 1; 379 n |= n >>> 1; 380 n |= n >>> 2; 381 n |= n >>> 4; 382 n |= n >>> 8; 383 n |= n >>> 16; 384 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1; 385 } 386 387 /* ---------------- Fields -------------- */ 388 389 /** 390 * The table, initialized on first use, and resized as 391 * necessary. When allocated, length is always a power of two. 392 * (We also tolerate length zero in some operations to allow 393 * bootstrapping mechanics that are currently not needed.) 394 */ 395 transient Node<K,V>[] table; 396 397 /** 398 * Holds cached entrySet(). Note that AbstractMap fields are used 399 * for keySet() and values(). 400 */ 401 transient Set<Map.Entry<K,V>> entrySet; 402 403 /** 404 * The number of key-value mappings contained in this map. 405 */ 406 transient int size; 407 408 /** 409 * The number of times this HashMap has been structurally modified 410 * Structural modifications are those that change the number of mappings in 411 * the HashMap or otherwise modify its internal structure (e.g., 412 * rehash). This field is used to make iterators on Collection-views of 413 * the HashMap fail-fast. (See ConcurrentModificationException). 414 */ 415 transient int modCount; 416 417 /** 418 * The next size value at which to resize (capacity * load factor). 419 * 420 * @serial 421 */ 422 // (The javadoc description is true upon serialization. 423 // Additionally, if the table array has not been allocated, this 424 // field holds the initial array capacity, or zero signifying 425 // DEFAULT_INITIAL_CAPACITY.) 426 int threshold; 427 428 /** 429 * The load factor for the hash table. 430 * 431 * @serial 432 */ 433 final float loadFactor; 434 435 /* ---------------- Public operations -------------- */ 436 437 /** 438 * Constructs an empty <tt>HashMap</tt> with the specified initial 439 * capacity and load factor. 440 * 441 * @param initialCapacity the initial capacity 442 * @param loadFactor the load factor 443 * @throws IllegalArgumentException if the initial capacity is negative 444 * or the load factor is nonpositive 445 */ 446 public HashMap(int initialCapacity, float loadFactor) { 447 if (initialCapacity < 0) 448 throw new IllegalArgumentException("Illegal initial capacity: " + 449 initialCapacity); 450 if (initialCapacity > MAXIMUM_CAPACITY) 451 initialCapacity = MAXIMUM_CAPACITY; 452 if (loadFactor <= 0 || Float.isNaN(loadFactor)) 453 throw new IllegalArgumentException("Illegal load factor: " + 454 loadFactor); 455 this.loadFactor = loadFactor; 456 this.threshold = tableSizeFor(initialCapacity); 457 } 458 459 /** 460 * Constructs an empty <tt>HashMap</tt> with the specified initial 461 * capacity and the default load factor (0.75). 462 * 463 * @param initialCapacity the initial capacity. 464 * @throws IllegalArgumentException if the initial capacity is negative. 465 */ 466 public HashMap(int initialCapacity) { 467 this(initialCapacity, DEFAULT_LOAD_FACTOR); 468 } 469 470 /** 471 * Constructs an empty <tt>HashMap</tt> with the default initial capacity 472 * (16) and the default load factor (0.75). 473 */ 474 public HashMap() { 475 this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted 476 } 477 478 /** 479 * Constructs a new <tt>HashMap</tt> with the same mappings as the 480 * specified <tt>Map</tt>. The <tt>HashMap</tt> is created with 481 * default load factor (0.75) and an initial capacity sufficient to 482 * hold the mappings in the specified <tt>Map</tt>. 483 * 484 * @param m the map whose mappings are to be placed in this map 485 * @throws NullPointerException if the specified map is null 486 */ 487 public HashMap(Map<? extends K, ? extends V> m) { 488 this.loadFactor = DEFAULT_LOAD_FACTOR; 489 putMapEntries(m, false); 490 } 491 492 /** 493 * Implements Map.putAll and Map constructor 494 * 495 * @param m the map 496 * @param evict false when initially constructing this map, else 497 * true (relayed to method afterNodeInsertion). 498 */ 499 final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) { 500 int s = m.size(); 501 if (s > 0) { 502 if (table == null) { // pre-size 503 float ft = ((float)s / loadFactor) + 1.0F; 504 int t = ((ft < (float)MAXIMUM_CAPACITY) ? 505 (int)ft : MAXIMUM_CAPACITY); 506 if (t > threshold) 507 threshold = tableSizeFor(t); 508 } 509 else if (s > threshold) 510 resize(); 511 for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) { 512 K key = e.getKey(); 513 V value = e.getValue(); 514 putVal(hash(key), key, value, false, evict); 515 } 516 } 517 } 518 519 /** 520 * Returns the number of key-value mappings in this map. 521 * 522 * @return the number of key-value mappings in this map 523 */ 524 public int size() { 525 return size; 526 } 527 528 /** 529 * Returns <tt>true</tt> if this map contains no key-value mappings. 530 * 531 * @return <tt>true</tt> if this map contains no key-value mappings 532 */ 533 public boolean isEmpty() { 534 return size == 0; 535 } 536 537 /** 538 * Returns the value to which the specified key is mapped, 539 * or {@code null} if this map contains no mapping for the key. 540 * 541 * <p>More formally, if this map contains a mapping from a key 542 * {@code k} to a value {@code v} such that {@code (key==null ? k==null : 543 * key.equals(k))}, then this method returns {@code v}; otherwise 544 * it returns {@code null}. (There can be at most one such mapping.) 545 * 546 * <p>A return value of {@code null} does not <i>necessarily</i> 547 * indicate that the map contains no mapping for the key; it's also 548 * possible that the map explicitly maps the key to {@code null}. 549 * The {@link #containsKey containsKey} operation may be used to 550 * distinguish these two cases. 551 * 552 * @see #put(Object, Object) 553 */ 554 public V get(Object key) { 555 Node<K,V> e; 556 return (e = getNode(hash(key), key)) == null ? null : e.value; 557 } 558 559 /** 560 * Implements Map.get and related methods 561 * 562 * @param hash hash for key 563 * @param key the key 564 * @return the node, or null if none 565 */ 566 final Node<K,V> getNode(int hash, Object key) { 567 Node<K,V>[] tab; Node<K,V> first, e; int n; K k; 568 if ((tab = table) != null && (n = tab.length) > 0 && 569 (first = tab[(n - 1) & hash]) != null) { 570 if (first.hash == hash && // always check first node 571 ((k = first.key) == key || (key != null && key.equals(k)))) 572 return first; 573 if ((e = first.next) != null) { 574 if (first instanceof TreeNode) 575 return ((TreeNode<K,V>)first).getTreeNode(hash, key); 576 do { 577 if (e.hash == hash && 578 ((k = e.key) == key || (key != null && key.equals(k)))) 579 return e; 580 } while ((e = e.next) != null); 581 } 582 } 583 return null; 584 } 585 586 /** 587 * Returns <tt>true</tt> if this map contains a mapping for the 588 * specified key. 589 * 590 * @param key The key whose presence in this map is to be tested 591 * @return <tt>true</tt> if this map contains a mapping for the specified 592 * key. 593 */ 594 public boolean containsKey(Object key) { 595 return getNode(hash(key), key) != null; 596 } 597 598 /** 599 * Associates the specified value with the specified key in this map. 600 * If the map previously contained a mapping for the key, the old 601 * value is replaced. 602 * 603 * @param key key with which the specified value is to be associated 604 * @param value value to be associated with the specified key 605 * @return the previous value associated with <tt>key</tt>, or 606 * <tt>null</tt> if there was no mapping for <tt>key</tt>. 607 * (A <tt>null</tt> return can also indicate that the map 608 * previously associated <tt>null</tt> with <tt>key</tt>.) 609 */ 610 public V put(K key, V value) { 611 return putVal(hash(key), key, value, false, true); 612 } 613 614 /** 615 * Implements Map.put and related methods 616 * 617 * @param hash hash for key 618 * @param key the key 619 * @param value the value to put 620 * @param onlyIfAbsent if true, don't change existing value 621 * @param evict if false, the table is in creation mode. 622 * @return previous value, or null if none 623 */ 624 final V putVal(int hash, K key, V value, boolean onlyIfAbsent, 625 boolean evict) { 626 Node<K,V>[] tab; Node<K,V> p; int n, i; 627 if ((tab = table) == null || (n = tab.length) == 0) 628 n = (tab = resize()).length; 629 if ((p = tab[i = (n - 1) & hash]) == null) 630 tab[i] = newNode(hash, key, value, null); 631 else { 632 Node<K,V> e; K k; 633 if (p.hash == hash && 634 ((k = p.key) == key || (key != null && key.equals(k)))) 635 e = p; 636 else if (p instanceof TreeNode) 637 e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value); 638 else { 639 for (int binCount = 0; ; ++binCount) { 640 if ((e = p.next) == null) { 641 p.next = newNode(hash, key, value, null); 642 if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st 643 treeifyBin(tab, hash); 644 break; 645 } 646 if (e.hash == hash && 647 ((k = e.key) == key || (key != null && key.equals(k)))) 648 break; 649 p = e; 650 } 651 } 652 if (e != null) { // existing mapping for key 653 V oldValue = e.value; 654 if (!onlyIfAbsent || oldValue == null) 655 e.value = value; 656 afterNodeAccess(e); 657 return oldValue; 658 } 659 } 660 ++modCount; 661 if (++size > threshold) 662 resize(); 663 afterNodeInsertion(evict); 664 return null; 665 } 666 667 /** 668 * Initializes or doubles table size. If null, allocates in 669 * accord with initial capacity target held in field threshold. 670 * Otherwise, because we are using power-of-two expansion, the 671 * elements from each bin must either stay at same index, or move 672 * with a power of two offset in the new table. 673 * 674 * @return the table 675 */ 676 final Node<K,V>[] resize() { 677 Node<K,V>[] oldTab = table; 678 int oldCap = (oldTab == null) ? 0 : oldTab.length; 679 int oldThr = threshold; 680 int newCap, newThr = 0; 681 if (oldCap > 0) { 682 if (oldCap >= MAXIMUM_CAPACITY) { 683 threshold = Integer.MAX_VALUE; 684 return oldTab; 685 } 686 else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY && 687 oldCap >= DEFAULT_INITIAL_CAPACITY) 688 newThr = oldThr << 1; // double threshold 689 } 690 else if (oldThr > 0) // initial capacity was placed in threshold 691 newCap = oldThr; 692 else { // zero initial threshold signifies using defaults 693 newCap = DEFAULT_INITIAL_CAPACITY; 694 newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY); 695 } 696 if (newThr == 0) { 697 float ft = (float)newCap * loadFactor; 698 newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ? 699 (int)ft : Integer.MAX_VALUE); 700 } 701 threshold = newThr; 702 @SuppressWarnings({"rawtypes","unchecked"}) 703 Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap]; 704 table = newTab; 705 if (oldTab != null) { 706 for (int j = 0; j < oldCap; ++j) { 707 Node<K,V> e; 708 if ((e = oldTab[j]) != null) { 709 oldTab[j] = null; 710 if (e.next == null) 711 newTab[e.hash & (newCap - 1)] = e; 712 else if (e instanceof TreeNode) 713 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap); 714 else { // preserve order 715 Node<K,V> loHead = null, loTail = null; 716 Node<K,V> hiHead = null, hiTail = null; 717 Node<K,V> next; 718 do { 719 next = e.next; 720 if ((e.hash & oldCap) == 0) { 721 if (loTail == null) 722 loHead = e; 723 else 724 loTail.next = e; 725 loTail = e; 726 } 727 else { 728 if (hiTail == null) 729 hiHead = e; 730 else 731 hiTail.next = e; 732 hiTail = e; 733 } 734 } while ((e = next) != null); 735 if (loTail != null) { 736 loTail.next = null; 737 newTab[j] = loHead; 738 } 739 if (hiTail != null) { 740 hiTail.next = null; 741 newTab[j + oldCap] = hiHead; 742 } 743 } 744 } 745 } 746 } 747 return newTab; 748 } 749 750 /** 751 * Replaces all linked nodes in bin at index for given hash unless 752 * table is too small, in which case resizes instead. 753 */ 754 final void treeifyBin(Node<K,V>[] tab, int hash) { 755 int n, index; Node<K,V> e; 756 if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY) 757 resize(); 758 else if ((e = tab[index = (n - 1) & hash]) != null) { 759 TreeNode<K,V> hd = null, tl = null; 760 do { 761 TreeNode<K,V> p = replacementTreeNode(e, null); 762 if (tl == null) 763 hd = p; 764 else { 765 p.prev = tl; 766 tl.next = p; 767 } 768 tl = p; 769 } while ((e = e.next) != null); 770 if ((tab[index] = hd) != null) 771 hd.treeify(tab); 772 } 773 } 774 775 /** 776 * Copies all of the mappings from the specified map to this map. 777 * These mappings will replace any mappings that this map had for 778 * any of the keys currently in the specified map. 779 * 780 * @param m mappings to be stored in this map 781 * @throws NullPointerException if the specified map is null 782 */ 783 public void putAll(Map<? extends K, ? extends V> m) { 784 putMapEntries(m, true); 785 } 786 787 /** 788 * Removes the mapping for the specified key from this map if present. 789 * 790 * @param key key whose mapping is to be removed from the map 791 * @return the previous value associated with <tt>key</tt>, or 792 * <tt>null</tt> if there was no mapping for <tt>key</tt>. 793 * (A <tt>null</tt> return can also indicate that the map 794 * previously associated <tt>null</tt> with <tt>key</tt>.) 795 */ 796 public V remove(Object key) { 797 Node<K,V> e; 798 return (e = removeNode(hash(key), key, null, false, true)) == null ? 799 null : e.value; 800 } 801 802 /** 803 * Implements Map.remove and related methods 804 * 805 * @param hash hash for key 806 * @param key the key 807 * @param value the value to match if matchValue, else ignored 808 * @param matchValue if true only remove if value is equal 809 * @param movable if false do not move other nodes while removing 810 * @return the node, or null if none 811 */ 812 final Node<K,V> removeNode(int hash, Object key, Object value, 813 boolean matchValue, boolean movable) { 814 Node<K,V>[] tab; Node<K,V> p; int n, index; 815 if ((tab = table) != null && (n = tab.length) > 0 && 816 (p = tab[index = (n - 1) & hash]) != null) { 817 Node<K,V> node = null, e; K k; V v; 818 if (p.hash == hash && 819 ((k = p.key) == key || (key != null && key.equals(k)))) 820 node = p; 821 else if ((e = p.next) != null) { 822 if (p instanceof TreeNode) 823 node = ((TreeNode<K,V>)p).getTreeNode(hash, key); 824 else { 825 do { 826 if (e.hash == hash && 827 ((k = e.key) == key || 828 (key != null && key.equals(k)))) { 829 node = e; 830 break; 831 } 832 p = e; 833 } while ((e = e.next) != null); 834 } 835 } 836 if (node != null && (!matchValue || (v = node.value) == value || 837 (value != null && value.equals(v)))) { 838 if (node instanceof TreeNode) 839 ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable); 840 else if (node == p) 841 tab[index] = node.next; 842 else 843 p.next = node.next; 844 ++modCount; 845 --size; 846 afterNodeRemoval(node); 847 return node; 848 } 849 } 850 return null; 851 } 852 853 /** 854 * Removes all of the mappings from this map. 855 * The map will be empty after this call returns. 856 */ 857 public void clear() { 858 Node<K,V>[] tab; 859 modCount++; 860 if ((tab = table) != null && size > 0) { 861 size = 0; 862 for (int i = 0; i < tab.length; ++i) 863 tab[i] = null; 864 } 865 } 866 867 /** 868 * Returns <tt>true</tt> if this map maps one or more keys to the 869 * specified value. 870 * 871 * @param value value whose presence in this map is to be tested 872 * @return <tt>true</tt> if this map maps one or more keys to the 873 * specified value 874 */ 875 public boolean containsValue(Object value) { 876 Node<K,V>[] tab; V v; 877 if ((tab = table) != null && size > 0) { 878 for (int i = 0; i < tab.length; ++i) { 879 for (Node<K,V> e = tab[i]; e != null; e = e.next) { 880 if ((v = e.value) == value || 881 (value != null && value.equals(v))) 882 return true; 883 } 884 } 885 } 886 return false; 887 } 888 889 /** 890 * Returns a {@link Set} view of the keys contained in this map. 891 * The set is backed by the map, so changes to the map are 892 * reflected in the set, and vice-versa. If the map is modified 893 * while an iteration over the set is in progress (except through 894 * the iterator's own <tt>remove</tt> operation), the results of 895 * the iteration are undefined. The set supports element removal, 896 * which removes the corresponding mapping from the map, via the 897 * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, 898 * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> 899 * operations. It does not support the <tt>add</tt> or <tt>addAll</tt> 900 * operations. 901 * 902 * @return a set view of the keys contained in this map 903 */ 904 public Set<K> keySet() { 905 Set<K> ks; 906 return (ks = keySet) == null ? (keySet = new KeySet()) : ks; 907 } 908 909 final class KeySet extends AbstractSet<K> { 910 public final int size() { return size; } 911 public final void clear() { HashMap.this.clear(); } 912 public final Iterator<K> iterator() { return new KeyIterator(); } 913 public final boolean contains(Object o) { return containsKey(o); } 914 public final boolean remove(Object key) { 915 return removeNode(hash(key), key, null, false, true) != null; 916 } 917 public final Spliterator<K> spliterator() { 918 return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0); 919 } 920 public final void forEach(Consumer<? super K> action) { 921 Node<K,V>[] tab; 922 if (action == null) 923 throw new NullPointerException(); 924 if (size > 0 && (tab = table) != null) { 925 int mc = modCount; 926 for (int i = 0; i < tab.length; ++i) { 927 for (Node<K,V> e = tab[i]; e != null; e = e.next) 928 action.accept(e.key); 929 } 930 if (modCount != mc) 931 throw new ConcurrentModificationException(); 932 } 933 } 934 } 935 936 /** 937 * Returns a {@link Collection} view of the values contained in this map. 938 * The collection is backed by the map, so changes to the map are 939 * reflected in the collection, and vice-versa. If the map is 940 * modified while an iteration over the collection is in progress 941 * (except through the iterator's own <tt>remove</tt> operation), 942 * the results of the iteration are undefined. The collection 943 * supports element removal, which removes the corresponding 944 * mapping from the map, via the <tt>Iterator.remove</tt>, 945 * <tt>Collection.remove</tt>, <tt>removeAll</tt>, 946 * <tt>retainAll</tt> and <tt>clear</tt> operations. It does not 947 * support the <tt>add</tt> or <tt>addAll</tt> operations. 948 * 949 * @return a view of the values contained in this map 950 */ 951 public Collection<V> values() { 952 Collection<V> vs; 953 return (vs = values) == null ? (values = new Values()) : vs; 954 } 955 956 final class Values extends AbstractCollection<V> { 957 public final int size() { return size; } 958 public final void clear() { HashMap.this.clear(); } 959 public final Iterator<V> iterator() { return new ValueIterator(); } 960 public final boolean contains(Object o) { return containsValue(o); } 961 public final Spliterator<V> spliterator() { 962 return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0); 963 } 964 public final void forEach(Consumer<? super V> action) { 965 Node<K,V>[] tab; 966 if (action == null) 967 throw new NullPointerException(); 968 if (size > 0 && (tab = table) != null) { 969 int mc = modCount; 970 for (int i = 0; i < tab.length; ++i) { 971 for (Node<K,V> e = tab[i]; e != null; e = e.next) 972 action.accept(e.value); 973 } 974 if (modCount != mc) 975 throw new ConcurrentModificationException(); 976 } 977 } 978 } 979 980 /** 981 * Returns a {@link Set} view of the mappings contained in this map. 982 * The set is backed by the map, so changes to the map are 983 * reflected in the set, and vice-versa. If the map is modified 984 * while an iteration over the set is in progress (except through 985 * the iterator's own <tt>remove</tt> operation, or through the 986 * <tt>setValue</tt> operation on a map entry returned by the 987 * iterator) the results of the iteration are undefined. The set 988 * supports element removal, which removes the corresponding 989 * mapping from the map, via the <tt>Iterator.remove</tt>, 990 * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and 991 * <tt>clear</tt> operations. It does not support the 992 * <tt>add</tt> or <tt>addAll</tt> operations. 993 * 994 * @return a set view of the mappings contained in this map 995 */ 996 public Set<Map.Entry<K,V>> entrySet() { 997 Set<Map.Entry<K,V>> es; 998 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es; 999 } 1000 1001 final class EntrySet extends AbstractSet<Map.Entry<K,V>> { 1002 public final int size() { return size; } 1003 public final void clear() { HashMap.this.clear(); } 1004 public final Iterator<Map.Entry<K,V>> iterator() { 1005 return new EntryIterator(); 1006 } 1007 public final boolean contains(Object o) { 1008 if (!(o instanceof Map.Entry)) 1009 return false; 1010 Map.Entry<?,?> e = (Map.Entry<?,?>) o; 1011 Object key = e.getKey(); 1012 Node<K,V> candidate = getNode(hash(key), key); 1013 return candidate != null && candidate.equals(e); 1014 } 1015 public final boolean remove(Object o) { 1016 if (o instanceof Map.Entry) { 1017 Map.Entry<?,?> e = (Map.Entry<?,?>) o; 1018 Object key = e.getKey(); 1019 Object value = e.getValue(); 1020 return removeNode(hash(key), key, value, true, true) != null; 1021 } 1022 return false; 1023 } 1024 public final Spliterator<Map.Entry<K,V>> spliterator() { 1025 return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0); 1026 } 1027 public final void forEach(Consumer<? super Map.Entry<K,V>> action) { 1028 Node<K,V>[] tab; 1029 if (action == null) 1030 throw new NullPointerException(); 1031 if (size > 0 && (tab = table) != null) { 1032 int mc = modCount; 1033 for (int i = 0; i < tab.length; ++i) { 1034 for (Node<K,V> e = tab[i]; e != null; e = e.next) 1035 action.accept(e); 1036 } 1037 if (modCount != mc) 1038 throw new ConcurrentModificationException(); 1039 } 1040 } 1041 } 1042 1043 // Overrides of JDK8 Map extension methods 1044 1045 @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 @Override 1086 public V computeIfAbsent(K key, 1087 Function<? super K, ? extends V> mappingFunction) { 1088 if (mappingFunction == null) 1089 throw new NullPointerException(); 1090 int hash = hash(key); 1091 Node<K,V>[] tab; Node<K,V> first; int n, i; 1092 int binCount = 0; 1093 TreeNode<K,V> t = null; 1094 Node<K,V> old = null; 1095 if (size > threshold || (tab = table) == null || 1096 (n = tab.length) == 0) 1097 n = (tab = resize()).length; 1098 if ((first = tab[i = (n - 1) & hash]) != null) { 1099 if (first instanceof TreeNode) 1100 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key); 1101 else { 1102 Node<K,V> e = first; K k; 1103 do { 1104 if (e.hash == hash && 1105 ((k = e.key) == key || (key != null && key.equals(k)))) { 1106 old = e; 1107 break; 1108 } 1109 ++binCount; 1110 } while ((e = e.next) != null); 1111 } 1112 V oldValue; 1113 if (old != null && (oldValue = old.value) != null) { 1114 afterNodeAccess(old); 1115 return oldValue; 1116 } 1117 } 1118 V v = mappingFunction.apply(key); 1119 if (old != null) { 1120 old.value = v; 1121 afterNodeAccess(old); 1122 return v; 1123 } 1124 else if (v == null) 1125 return null; 1126 else if (t != null) 1127 t.putTreeVal(this, tab, hash, key, v); 1128 else { 1129 tab[i] = newNode(hash, key, v, first); 1130 if (binCount >= TREEIFY_THRESHOLD - 1) 1131 treeifyBin(tab, hash); 1132 } 1133 ++modCount; 1134 ++size; 1135 afterNodeInsertion(true); 1136 return v; 1137 } 1138 1139 public V computeIfPresent(K key, 1140 BiFunction<? super K, ? super V, ? extends V> remappingFunction) { 1141 if (remappingFunction == null) 1142 throw new NullPointerException(); 1143 Node<K,V> e; V oldValue; 1144 int hash = hash(key); 1145 if ((e = getNode(hash, key)) != null && 1146 (oldValue = e.value) != null) { 1147 V v = remappingFunction.apply(key, oldValue); 1148 if (v != null) { 1149 e.value = v; 1150 afterNodeAccess(e); 1151 return v; 1152 } 1153 else 1154 removeNode(hash, key, null, false, true); 1155 } 1156 return null; 1157 } 1158 1159 @Override 1160 public V compute(K key, 1161 BiFunction<? super K, ? super V, ? extends V> remappingFunction) { 1162 if (remappingFunction == null) 1163 throw new NullPointerException(); 1164 int hash = hash(key); 1165 Node<K,V>[] tab; Node<K,V> first; int n, i; 1166 int binCount = 0; 1167 TreeNode<K,V> t = null; 1168 Node<K,V> old = null; 1169 if (size > threshold || (tab = table) == null || 1170 (n = tab.length) == 0) 1171 n = (tab = resize()).length; 1172 if ((first = tab[i = (n - 1) & hash]) != null) { 1173 if (first instanceof TreeNode) 1174 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key); 1175 else { 1176 Node<K,V> e = first; K k; 1177 do { 1178 if (e.hash == hash && 1179 ((k = e.key) == key || (key != null && key.equals(k)))) { 1180 old = e; 1181 break; 1182 } 1183 ++binCount; 1184 } while ((e = e.next) != null); 1185 } 1186 } 1187 V oldValue = (old == null) ? null : old.value; 1188 V v = remappingFunction.apply(key, oldValue); 1189 if (old != null) { 1190 if (v != null) { 1191 old.value = v; 1192 afterNodeAccess(old); 1193 } 1194 else 1195 removeNode(hash, key, null, false, true); 1196 } 1197 else if (v != null) { 1198 if (t != null) 1199 t.putTreeVal(this, tab, hash, key, v); 1200 else { 1201 tab[i] = newNode(hash, key, v, first); 1202 if (binCount >= TREEIFY_THRESHOLD - 1) 1203 treeifyBin(tab, hash); 1204 } 1205 ++modCount; 1206 ++size; 1207 afterNodeInsertion(true); 1208 } 1209 return v; 1210 } 1211 1212 @Override 1213 public V merge(K key, V value, 1214 BiFunction<? super V, ? super V, ? extends V> remappingFunction) { 1215 if (value == null) 1216 throw new NullPointerException(); 1217 if (remappingFunction == null) 1218 throw new NullPointerException(); 1219 int hash = hash(key); 1220 Node<K,V>[] tab; Node<K,V> first; int n, i; 1221 int binCount = 0; 1222 TreeNode<K,V> t = null; 1223 Node<K,V> old = null; 1224 if (size > threshold || (tab = table) == null || 1225 (n = tab.length) == 0) 1226 n = (tab = resize()).length; 1227 if ((first = tab[i = (n - 1) & hash]) != null) { 1228 if (first instanceof TreeNode) 1229 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key); 1230 else { 1231 Node<K,V> e = first; K k; 1232 do { 1233 if (e.hash == hash && 1234 ((k = e.key) == key || (key != null && key.equals(k)))) { 1235 old = e; 1236 break; 1237 } 1238 ++binCount; 1239 } while ((e = e.next) != null); 1240 } 1241 } 1242 if (old != null) { 1243 V v; 1244 if (old.value != null) 1245 v = remappingFunction.apply(old.value, value); 1246 else 1247 v = value; 1248 if (v != null) { 1249 old.value = v; 1250 afterNodeAccess(old); 1251 } 1252 else 1253 removeNode(hash, key, null, false, true); 1254 return v; 1255 } 1256 if (value != null) { 1257 if (t != null) 1258 t.putTreeVal(this, tab, hash, key, value); 1259 else { 1260 tab[i] = newNode(hash, key, value, first); 1261 if (binCount >= TREEIFY_THRESHOLD - 1) 1262 treeifyBin(tab, hash); 1263 } 1264 ++modCount; 1265 ++size; 1266 afterNodeInsertion(true); 1267 } 1268 return value; 1269 } 1270 1271 @Override 1272 public void forEach(BiConsumer<? super K, ? super V> action) { 1273 Node<K,V>[] tab; 1274 if (action == null) 1275 throw new NullPointerException(); 1276 if (size > 0 && (tab = table) != null) { 1277 int mc = modCount; 1278 for (int i = 0; i < tab.length; ++i) { 1279 for (Node<K,V> e = tab[i]; e != null; e = e.next) 1280 action.accept(e.key, e.value); 1281 } 1282 if (modCount != mc) 1283 throw new ConcurrentModificationException(); 1284 } 1285 } 1286 1287 @Override 1288 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) { 1289 Node<K,V>[] tab; 1290 if (function == null) 1291 throw new NullPointerException(); 1292 if (size > 0 && (tab = table) != null) { 1293 int mc = modCount; 1294 for (int i = 0; i < tab.length; ++i) { 1295 for (Node<K,V> e = tab[i]; e != null; e = e.next) { 1296 e.value = function.apply(e.key, e.value); 1297 } 1298 } 1299 if (modCount != mc) 1300 throw new ConcurrentModificationException(); 1301 } 1302 } 1303 1304 /* ------------------------------------------------------------ */ 1305 // Cloning and serialization 1306 1307 /** 1308 * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and 1309 * values themselves are not cloned. 1310 * 1311 * @return a shallow copy of this map 1312 */ 1313 @SuppressWarnings("unchecked") 1314 @Override 1315 public Object clone() { 1316 HashMap<K,V> result; 1317 try { 1318 result = (HashMap<K,V>)super.clone(); 1319 } catch (CloneNotSupportedException e) { 1320 // this shouldn't happen, since we are Cloneable 1321 throw new InternalError(e); 1322 } 1323 result.reinitialize(); 1324 result.putMapEntries(this, false); 1325 return result; 1326 } 1327 1328 // These methods are also used when serializing HashSets 1329 final float loadFactor() { return loadFactor; } 1330 final int capacity() { 1331 return (table != null) ? table.length : 1332 (threshold > 0) ? threshold : 1333 DEFAULT_INITIAL_CAPACITY; 1334 } 1335 1336 /** 1337 * Save the state of the <tt>HashMap</tt> instance to a stream (i.e., 1338 * serialize it). 1339 * 1340 * @serialData The <i>capacity</i> of the HashMap (the length of the 1341 * bucket array) is emitted (int), followed by the 1342 * <i>size</i> (an int, the number of key-value 1343 * mappings), followed by the key (Object) and value (Object) 1344 * for each key-value mapping. The key-value mappings are 1345 * emitted in no particular order. 1346 */ 1347 private void writeObject(java.io.ObjectOutputStream s) 1348 throws IOException { 1349 int buckets = capacity(); 1350 // Write out the threshold, loadfactor, and any hidden stuff 1351 s.defaultWriteObject(); 1352 s.writeInt(buckets); 1353 s.writeInt(size); 1354 internalWriteEntries(s); 1355 } 1356 1357 /** 1358 * Reconstitute the {@code HashMap} instance from a stream (i.e., 1359 * deserialize it). 1360 */ 1361 private void readObject(java.io.ObjectInputStream s) 1362 throws IOException, ClassNotFoundException { 1363 // Read in the threshold (ignored), loadfactor, and any hidden stuff 1364 s.defaultReadObject(); 1365 reinitialize(); 1366 if (loadFactor <= 0 || Float.isNaN(loadFactor)) 1367 throw new InvalidObjectException("Illegal load factor: " + 1368 loadFactor); 1369 s.readInt(); // Read and ignore number of buckets 1370 int mappings = s.readInt(); // Read number of mappings (size) 1371 if (mappings < 0) 1372 throw new InvalidObjectException("Illegal mappings count: " + 1373 mappings); 1374 else if (mappings > 0) { // (if zero, use defaults) 1375 // Size the table using given load factor only if within 1376 // range of 0.25...4.0 1377 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f); 1378 float fc = (float)mappings / lf + 1.0f; 1379 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ? 1380 DEFAULT_INITIAL_CAPACITY : 1381 (fc >= MAXIMUM_CAPACITY) ? 1382 MAXIMUM_CAPACITY : 1383 tableSizeFor((int)fc)); 1384 float ft = (float)cap * lf; 1385 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ? 1386 (int)ft : Integer.MAX_VALUE); 1387 @SuppressWarnings({"rawtypes","unchecked"}) 1388 Node<K,V>[] tab = (Node<K,V>[])new Node[cap]; 1389 table = tab; 1390 1391 // Read the keys and values, and put the mappings in the HashMap 1392 for (int i = 0; i < mappings; i++) { 1393 @SuppressWarnings("unchecked") 1394 K key = (K) s.readObject(); 1395 @SuppressWarnings("unchecked") 1396 V value = (V) s.readObject(); 1397 putVal(hash(key), key, value, false, false); 1398 } 1399 } 1400 } 1401 1402 /* ------------------------------------------------------------ */ 1403 // iterators 1404 1405 abstract class HashIterator { 1406 Node<K,V> next; // next entry to return 1407 Node<K,V> current; // current entry 1408 int expectedModCount; // for fast-fail 1409 int index; // current slot 1410 1411 HashIterator() { 1412 expectedModCount = modCount; 1413 Node<K,V>[] t = table; 1414 current = next = null; 1415 index = 0; 1416 if (t != null && size > 0) { // advance to first entry 1417 do {} while (index < t.length && (next = t[index++]) == null); 1418 } 1419 } 1420 1421 public final boolean hasNext() { 1422 return next != null; 1423 } 1424 1425 final Node<K,V> nextNode() { 1426 Node<K,V>[] t; 1427 Node<K,V> e = next; 1428 if (modCount != expectedModCount) 1429 throw new ConcurrentModificationException(); 1430 if (e == null) 1431 throw new NoSuchElementException(); 1432 if ((next = (current = e).next) == null && (t = table) != null) { 1433 do {} while (index < t.length && (next = t[index++]) == null); 1434 } 1435 return e; 1436 } 1437 1438 public final void remove() { 1439 Node<K,V> p = current; 1440 if (p == null) 1441 throw new IllegalStateException(); 1442 if (modCount != expectedModCount) 1443 throw new ConcurrentModificationException(); 1444 current = null; 1445 K key = p.key; 1446 removeNode(hash(key), key, null, false, false); 1447 expectedModCount = modCount; 1448 } 1449 } 1450 1451 final class KeyIterator extends HashIterator 1452 implements Iterator<K> { 1453 public final K next() { return nextNode().key; } 1454 } 1455 1456 final class ValueIterator extends HashIterator 1457 implements Iterator<V> { 1458 public final V next() { return nextNode().value; } 1459 } 1460 1461 final class EntryIterator extends HashIterator 1462 implements Iterator<Map.Entry<K,V>> { 1463 public final Map.Entry<K,V> next() { return nextNode(); } 1464 } 1465 1466 /* ------------------------------------------------------------ */ 1467 // spliterators 1468 1469 static class HashMapSpliterator<K,V> { 1470 final HashMap<K,V> map; 1471 Node<K,V> current; // current node 1472 int index; // current index, modified on advance/split 1473 int fence; // one past last index 1474 int est; // size estimate 1475 int expectedModCount; // for comodification checks 1476 1477 HashMapSpliterator(HashMap<K,V> m, int origin, 1478 int fence, int est, 1479 int expectedModCount) { 1480 this.map = m; 1481 this.index = origin; 1482 this.fence = fence; 1483 this.est = est; 1484 this.expectedModCount = expectedModCount; 1485 } 1486 1487 final int getFence() { // initialize fence and size on first use 1488 int hi; 1489 if ((hi = fence) < 0) { 1490 HashMap<K,V> m = map; 1491 est = m.size; 1492 expectedModCount = m.modCount; 1493 Node<K,V>[] tab = m.table; 1494 hi = fence = (tab == null) ? 0 : tab.length; 1495 } 1496 return hi; 1497 } 1498 1499 public final long estimateSize() { 1500 getFence(); // force init 1501 return (long) est; 1502 } 1503 } 1504 1505 static final class KeySpliterator<K,V> 1506 extends HashMapSpliterator<K,V> 1507 implements Spliterator<K> { 1508 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est, 1509 int expectedModCount) { 1510 super(m, origin, fence, est, expectedModCount); 1511 } 1512 1513 public KeySpliterator<K,V> trySplit() { 1514 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1515 return (lo >= mid || current != null) ? null : 1516 new KeySpliterator<>(map, lo, index = mid, est >>>= 1, 1517 expectedModCount); 1518 } 1519 1520 public void forEachRemaining(Consumer<? super K> action) { 1521 int i, hi, mc; 1522 if (action == null) 1523 throw new NullPointerException(); 1524 HashMap<K,V> m = map; 1525 Node<K,V>[] tab = m.table; 1526 if ((hi = fence) < 0) { 1527 mc = expectedModCount = m.modCount; 1528 hi = fence = (tab == null) ? 0 : tab.length; 1529 } 1530 else 1531 mc = expectedModCount; 1532 if (tab != null && tab.length >= hi && 1533 (i = index) >= 0 && (i < (index = hi) || current != null)) { 1534 Node<K,V> p = current; 1535 current = null; 1536 do { 1537 if (p == null) 1538 p = tab[i++]; 1539 else { 1540 action.accept(p.key); 1541 p = p.next; 1542 } 1543 } while (p != null || i < hi); 1544 if (m.modCount != mc) 1545 throw new ConcurrentModificationException(); 1546 } 1547 } 1548 1549 public boolean tryAdvance(Consumer<? super K> action) { 1550 int hi; 1551 if (action == null) 1552 throw new NullPointerException(); 1553 Node<K,V>[] tab = map.table; 1554 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) { 1555 while (current != null || index < hi) { 1556 if (current == null) 1557 current = tab[index++]; 1558 else { 1559 K k = current.key; 1560 current = current.next; 1561 action.accept(k); 1562 if (map.modCount != expectedModCount) 1563 throw new ConcurrentModificationException(); 1564 return true; 1565 } 1566 } 1567 } 1568 return false; 1569 } 1570 1571 public int characteristics() { 1572 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) | 1573 Spliterator.DISTINCT; 1574 } 1575 } 1576 1577 static final class ValueSpliterator<K,V> 1578 extends HashMapSpliterator<K,V> 1579 implements Spliterator<V> { 1580 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est, 1581 int expectedModCount) { 1582 super(m, origin, fence, est, expectedModCount); 1583 } 1584 1585 public ValueSpliterator<K,V> trySplit() { 1586 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1587 return (lo >= mid || current != null) ? null : 1588 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1, 1589 expectedModCount); 1590 } 1591 1592 public void forEachRemaining(Consumer<? super V> action) { 1593 int i, hi, mc; 1594 if (action == null) 1595 throw new NullPointerException(); 1596 HashMap<K,V> m = map; 1597 Node<K,V>[] tab = m.table; 1598 if ((hi = fence) < 0) { 1599 mc = expectedModCount = m.modCount; 1600 hi = fence = (tab == null) ? 0 : tab.length; 1601 } 1602 else 1603 mc = expectedModCount; 1604 if (tab != null && tab.length >= hi && 1605 (i = index) >= 0 && (i < (index = hi) || current != null)) { 1606 Node<K,V> p = current; 1607 current = null; 1608 do { 1609 if (p == null) 1610 p = tab[i++]; 1611 else { 1612 action.accept(p.value); 1613 p = p.next; 1614 } 1615 } while (p != null || i < hi); 1616 if (m.modCount != mc) 1617 throw new ConcurrentModificationException(); 1618 } 1619 } 1620 1621 public boolean tryAdvance(Consumer<? super V> action) { 1622 int hi; 1623 if (action == null) 1624 throw new NullPointerException(); 1625 Node<K,V>[] tab = map.table; 1626 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) { 1627 while (current != null || index < hi) { 1628 if (current == null) 1629 current = tab[index++]; 1630 else { 1631 V v = current.value; 1632 current = current.next; 1633 action.accept(v); 1634 if (map.modCount != expectedModCount) 1635 throw new ConcurrentModificationException(); 1636 return true; 1637 } 1638 } 1639 } 1640 return false; 1641 } 1642 1643 public int characteristics() { 1644 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0); 1645 } 1646 } 1647 1648 static final class EntrySpliterator<K,V> 1649 extends HashMapSpliterator<K,V> 1650 implements Spliterator<Map.Entry<K,V>> { 1651 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est, 1652 int expectedModCount) { 1653 super(m, origin, fence, est, expectedModCount); 1654 } 1655 1656 public EntrySpliterator<K,V> trySplit() { 1657 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1658 return (lo >= mid || current != null) ? null : 1659 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1, 1660 expectedModCount); 1661 } 1662 1663 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) { 1664 int i, hi, mc; 1665 if (action == null) 1666 throw new NullPointerException(); 1667 HashMap<K,V> m = map; 1668 Node<K,V>[] tab = m.table; 1669 if ((hi = fence) < 0) { 1670 mc = expectedModCount = m.modCount; 1671 hi = fence = (tab == null) ? 0 : tab.length; 1672 } 1673 else 1674 mc = expectedModCount; 1675 if (tab != null && tab.length >= hi && 1676 (i = index) >= 0 && (i < (index = hi) || current != null)) { 1677 Node<K,V> p = current; 1678 current = null; 1679 do { 1680 if (p == null) 1681 p = tab[i++]; 1682 else { 1683 action.accept(p); 1684 p = p.next; 1685 } 1686 } while (p != null || i < hi); 1687 if (m.modCount != mc) 1688 throw new ConcurrentModificationException(); 1689 } 1690 } 1691 1692 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) { 1693 int hi; 1694 if (action == null) 1695 throw new NullPointerException(); 1696 Node<K,V>[] tab = map.table; 1697 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) { 1698 while (current != null || index < hi) { 1699 if (current == null) 1700 current = tab[index++]; 1701 else { 1702 Node<K,V> e = current; 1703 current = current.next; 1704 action.accept(e); 1705 if (map.modCount != expectedModCount) 1706 throw new ConcurrentModificationException(); 1707 return true; 1708 } 1709 } 1710 } 1711 return false; 1712 } 1713 1714 public int characteristics() { 1715 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) | 1716 Spliterator.DISTINCT; 1717 } 1718 } 1719 1720 /* ------------------------------------------------------------ */ 1721 // LinkedHashMap support 1722 1723 1724 /* 1725 * The following package-protected methods are designed to be 1726 * overridden by LinkedHashMap, but not by any other subclass. 1727 * Nearly all other internal methods are also package-protected 1728 * but are declared final, so can be used by LinkedHashMap, view 1729 * classes, and HashSet. 1730 */ 1731 1732 // Create a regular (non-tree) node 1733 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) { 1734 return new Node<>(hash, key, value, next); 1735 } 1736 1737 // For conversion from TreeNodes to plain nodes 1738 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) { 1739 return new Node<>(p.hash, p.key, p.value, next); 1740 } 1741 1742 // Create a tree bin node 1743 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) { 1744 return new TreeNode<>(hash, key, value, next); 1745 } 1746 1747 // For treeifyBin 1748 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) { 1749 return new TreeNode<>(p.hash, p.key, p.value, next); 1750 } 1751 1752 /** 1753 * Reset to initial default state. Called by clone and readObject. 1754 */ 1755 void reinitialize() { 1756 table = null; 1757 entrySet = null; 1758 keySet = null; 1759 values = null; 1760 modCount = 0; 1761 threshold = 0; 1762 size = 0; 1763 } 1764 1765 // Callbacks to allow LinkedHashMap post-actions 1766 void afterNodeAccess(Node<K,V> p) { } 1767 void afterNodeInsertion(boolean evict) { } 1768 void afterNodeRemoval(Node<K,V> p) { } 1769 1770 // Called only from writeObject, to ensure compatible ordering. 1771 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException { 1772 Node<K,V>[] tab; 1773 if (size > 0 && (tab = table) != null) { 1774 for (int i = 0; i < tab.length; ++i) { 1775 for (Node<K,V> e = tab[i]; e != null; e = e.next) { 1776 s.writeObject(e.key); 1777 s.writeObject(e.value); 1778 } 1779 } 1780 } 1781 } 1782 1783 /* ------------------------------------------------------------ */ 1784 // Tree bins 1785 1786 /** 1787 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn 1788 * extends Node) so can be used as extension of either regular or 1789 * linked node. 1790 */ 1791 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> { 1792 TreeNode<K,V> parent; // red-black tree links 1793 TreeNode<K,V> left; 1794 TreeNode<K,V> right; 1795 TreeNode<K,V> prev; // needed to unlink next upon deletion 1796 boolean red; 1797 TreeNode(int hash, K key, V val, Node<K,V> next) { 1798 super(hash, key, val, next); 1799 } 1800 1801 /** 1802 * Returns root of tree containing this node. 1803 */ 1804 final TreeNode<K,V> root() { 1805 for (TreeNode<K,V> r = this, p;;) { 1806 if ((p = r.parent) == null) 1807 return r; 1808 r = p; 1809 } 1810 } 1811 1812 /** 1813 * Ensures that the given root is the first node of its bin. 1814 */ 1815 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) { 1816 int n; 1817 if (root != null && tab != null && (n = tab.length) > 0) { 1818 int index = (n - 1) & root.hash; 1819 TreeNode<K,V> first = (TreeNode<K,V>)tab[index]; 1820 if (root != first) { 1821 Node<K,V> rn; 1822 tab[index] = root; 1823 TreeNode<K,V> rp = root.prev; 1824 if ((rn = root.next) != null) 1825 ((TreeNode<K,V>)rn).prev = rp; 1826 if (rp != null) 1827 rp.next = rn; 1828 if (first != null) 1829 first.prev = root; 1830 root.next = first; 1831 root.prev = null; 1832 } 1833 assert checkInvariants(root); 1834 } 1835 } 1836 1837 /** 1838 * Finds the node starting at root p with the given hash and key. 1839 * The kc argument caches comparableClassFor(key) upon first use 1840 * comparing keys. 1841 */ 1842 final TreeNode<K,V> find(int h, Object k, Class<?> kc) { 1843 TreeNode<K,V> p = this; 1844 do { 1845 int ph, dir; K pk; 1846 TreeNode<K,V> pl = p.left, pr = p.right, q; 1847 if ((ph = p.hash) > h) 1848 p = pl; 1849 else if (ph < h) 1850 p = pr; 1851 else if ((pk = p.key) == k || (k != null && k.equals(pk))) 1852 return p; 1853 else if (pl == null) 1854 p = pr; 1855 else if (pr == null) 1856 p = pl; 1857 else if ((kc != null || 1858 (kc = comparableClassFor(k)) != null) && 1859 (dir = compareComparables(kc, k, pk)) != 0) 1860 p = (dir < 0) ? pl : pr; 1861 else if ((q = pr.find(h, k, kc)) != null) 1862 return q; 1863 else 1864 p = pl; 1865 } while (p != null); 1866 return null; 1867 } 1868 1869 /** 1870 * Calls find for root node. 1871 */ 1872 final TreeNode<K,V> getTreeNode(int h, Object k) { 1873 return ((parent != null) ? root() : this).find(h, k, null); 1874 } 1875 1876 /** 1877 * Tie-breaking utility for ordering insertions when equal 1878 * hashCodes and non-comparable. We don't require a total 1879 * order, just a consistent insertion rule to maintain 1880 * equivalence across rebalancings. Tie-breaking further than 1881 * necessary simplifies testing a bit. 1882 */ 1883 static int tieBreakOrder(Object a, Object b) { 1884 int d; 1885 if (a == null || b == null || 1886 (d = a.getClass().getName(). 1887 compareTo(b.getClass().getName())) == 0) 1888 d = (System.identityHashCode(a) <= System.identityHashCode(b) ? 1889 -1 : 1); 1890 return d; 1891 } 1892 1893 /** 1894 * Forms tree of the nodes linked from this node. 1895 * @return root of tree 1896 */ 1897 final void treeify(Node<K,V>[] tab) { 1898 TreeNode<K,V> root = null; 1899 for (TreeNode<K,V> x = this, next; x != null; x = next) { 1900 next = (TreeNode<K,V>)x.next; 1901 x.left = x.right = null; 1902 if (root == null) { 1903 x.parent = null; 1904 x.red = false; 1905 root = x; 1906 } 1907 else { 1908 K k = x.key; 1909 int h = x.hash; 1910 Class<?> kc = null; 1911 for (TreeNode<K,V> p = root;;) { 1912 int dir, ph; 1913 K pk = p.key; 1914 if ((ph = p.hash) > h) 1915 dir = -1; 1916 else if (ph < h) 1917 dir = 1; 1918 else if ((kc == null && 1919 (kc = comparableClassFor(k)) == null) || 1920 (dir = compareComparables(kc, k, pk)) == 0) 1921 dir = tieBreakOrder(k, pk); 1922 1923 TreeNode<K,V> xp = p; 1924 if ((p = (dir <= 0) ? p.left : p.right) == null) { 1925 x.parent = xp; 1926 if (dir <= 0) 1927 xp.left = x; 1928 else 1929 xp.right = x; 1930 root = balanceInsertion(root, x); 1931 break; 1932 } 1933 } 1934 } 1935 } 1936 moveRootToFront(tab, root); 1937 } 1938 1939 /** 1940 * Returns a list of non-TreeNodes replacing those linked from 1941 * this node. 1942 */ 1943 final Node<K,V> untreeify(HashMap<K,V> map) { 1944 Node<K,V> hd = null, tl = null; 1945 for (Node<K,V> q = this; q != null; q = q.next) { 1946 Node<K,V> p = map.replacementNode(q, null); 1947 if (tl == null) 1948 hd = p; 1949 else 1950 tl.next = p; 1951 tl = p; 1952 } 1953 return hd; 1954 } 1955 1956 /** 1957 * Tree version of putVal. 1958 */ 1959 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab, 1960 int h, K k, V v) { 1961 Class<?> kc = null; 1962 boolean searched = false; 1963 TreeNode<K,V> root = (parent != null) ? root() : this; 1964 for (TreeNode<K,V> p = root;;) { 1965 int dir, ph; K pk; 1966 if ((ph = p.hash) > h) 1967 dir = -1; 1968 else if (ph < h) 1969 dir = 1; 1970 else if ((pk = p.key) == k || (pk != null && k.equals(pk))) 1971 return p; 1972 else if ((kc == null && 1973 (kc = comparableClassFor(k)) == null) || 1974 (dir = compareComparables(kc, k, pk)) == 0) { 1975 if (!searched) { 1976 TreeNode<K,V> q, ch; 1977 searched = true; 1978 if (((ch = p.left) != null && 1979 (q = ch.find(h, k, kc)) != null) || 1980 ((ch = p.right) != null && 1981 (q = ch.find(h, k, kc)) != null)) 1982 return q; 1983 } 1984 dir = tieBreakOrder(k, pk); 1985 } 1986 1987 TreeNode<K,V> xp = p; 1988 if ((p = (dir <= 0) ? p.left : p.right) == null) { 1989 Node<K,V> xpn = xp.next; 1990 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn); 1991 if (dir <= 0) 1992 xp.left = x; 1993 else 1994 xp.right = x; 1995 xp.next = x; 1996 x.parent = x.prev = xp; 1997 if (xpn != null) 1998 ((TreeNode<K,V>)xpn).prev = x; 1999 moveRootToFront(tab, balanceInsertion(root, x)); 2000 return null; 2001 } 2002 } 2003 } 2004 2005 /** 2006 * Removes the given node, that must be present before this call. 2007 * This is messier than typical red-black deletion code because we 2008 * cannot swap the contents of an interior node with a leaf 2009 * successor that is pinned by "next" pointers that are accessible 2010 * independently during traversal. So instead we swap the tree 2011 * linkages. If the current tree appears to have too few nodes, 2012 * the bin is converted back to a plain bin. (The test triggers 2013 * somewhere between 2 and 6 nodes, depending on tree structure). 2014 */ 2015 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab, 2016 boolean movable) { 2017 int n; 2018 if (tab == null || (n = tab.length) == 0) 2019 return; 2020 int index = (n - 1) & hash; 2021 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl; 2022 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev; 2023 if (pred == null) 2024 tab[index] = first = succ; 2025 else 2026 pred.next = succ; 2027 if (succ != null) 2028 succ.prev = pred; 2029 if (first == null) 2030 return; 2031 if (root.parent != null) 2032 root = root.root(); 2033 if (root == null || root.right == null || 2034 (rl = root.left) == null || rl.left == null) { 2035 tab[index] = first.untreeify(map); // too small 2036 return; 2037 } 2038 TreeNode<K,V> p = this, pl = left, pr = right, replacement; 2039 if (pl != null && pr != null) { 2040 TreeNode<K,V> s = pr, sl; 2041 while ((sl = s.left) != null) // find successor 2042 s = sl; 2043 boolean c = s.red; s.red = p.red; p.red = c; // swap colors 2044 TreeNode<K,V> sr = s.right; 2045 TreeNode<K,V> pp = p.parent; 2046 if (s == pr) { // p was s's direct parent 2047 p.parent = s; 2048 s.right = p; 2049 } 2050 else { 2051 TreeNode<K,V> sp = s.parent; 2052 if ((p.parent = sp) != null) { 2053 if (s == sp.left) 2054 sp.left = p; 2055 else 2056 sp.right = p; 2057 } 2058 if ((s.right = pr) != null) 2059 pr.parent = s; 2060 } 2061 p.left = null; 2062 if ((p.right = sr) != null) 2063 sr.parent = p; 2064 if ((s.left = pl) != null) 2065 pl.parent = s; 2066 if ((s.parent = pp) == null) 2067 root = s; 2068 else if (p == pp.left) 2069 pp.left = s; 2070 else 2071 pp.right = s; 2072 if (sr != null) 2073 replacement = sr; 2074 else 2075 replacement = p; 2076 } 2077 else if (pl != null) 2078 replacement = pl; 2079 else if (pr != null) 2080 replacement = pr; 2081 else 2082 replacement = p; 2083 if (replacement != p) { 2084 TreeNode<K,V> pp = replacement.parent = p.parent; 2085 if (pp == null) 2086 root = replacement; 2087 else if (p == pp.left) 2088 pp.left = replacement; 2089 else 2090 pp.right = replacement; 2091 p.left = p.right = p.parent = null; 2092 } 2093 2094 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement); 2095 2096 if (replacement == p) { // detach 2097 TreeNode<K,V> pp = p.parent; 2098 p.parent = null; 2099 if (pp != null) { 2100 if (p == pp.left) 2101 pp.left = null; 2102 else if (p == pp.right) 2103 pp.right = null; 2104 } 2105 } 2106 if (movable) 2107 moveRootToFront(tab, r); 2108 } 2109 2110 /** 2111 * Splits nodes in a tree bin into lower and upper tree bins, 2112 * or untreeifies if now too small. Called only from resize; 2113 * see above discussion about split bits and indices. 2114 * 2115 * @param map the map 2116 * @param tab the table for recording bin heads 2117 * @param index the index of the table being split 2118 * @param bit the bit of hash to split on 2119 */ 2120 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) { 2121 TreeNode<K,V> b = this; 2122 // Relink into lo and hi lists, preserving order 2123 TreeNode<K,V> loHead = null, loTail = null; 2124 TreeNode<K,V> hiHead = null, hiTail = null; 2125 int lc = 0, hc = 0; 2126 for (TreeNode<K,V> e = b, next; e != null; e = next) { 2127 next = (TreeNode<K,V>)e.next; 2128 e.next = null; 2129 if ((e.hash & bit) == 0) { 2130 if ((e.prev = loTail) == null) 2131 loHead = e; 2132 else 2133 loTail.next = e; 2134 loTail = e; 2135 ++lc; 2136 } 2137 else { 2138 if ((e.prev = hiTail) == null) 2139 hiHead = e; 2140 else 2141 hiTail.next = e; 2142 hiTail = e; 2143 ++hc; 2144 } 2145 } 2146 2147 if (loHead != null) { 2148 if (lc <= UNTREEIFY_THRESHOLD) 2149 tab[index] = loHead.untreeify(map); 2150 else { 2151 tab[index] = loHead; 2152 if (hiHead != null) // (else is already treeified) 2153 loHead.treeify(tab); 2154 } 2155 } 2156 if (hiHead != null) { 2157 if (hc <= UNTREEIFY_THRESHOLD) 2158 tab[index + bit] = hiHead.untreeify(map); 2159 else { 2160 tab[index + bit] = hiHead; 2161 if (loHead != null) 2162 hiHead.treeify(tab); 2163 } 2164 } 2165 } 2166 2167 /* ------------------------------------------------------------ */ 2168 // Red-black tree methods, all adapted from CLR 2169 2170 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root, 2171 TreeNode<K,V> p) { 2172 TreeNode<K,V> r, pp, rl; 2173 if (p != null && (r = p.right) != null) { 2174 if ((rl = p.right = r.left) != null) 2175 rl.parent = p; 2176 if ((pp = r.parent = p.parent) == null) 2177 (root = r).red = false; 2178 else if (pp.left == p) 2179 pp.left = r; 2180 else 2181 pp.right = r; 2182 r.left = p; 2183 p.parent = r; 2184 } 2185 return root; 2186 } 2187 2188 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root, 2189 TreeNode<K,V> p) { 2190 TreeNode<K,V> l, pp, lr; 2191 if (p != null && (l = p.left) != null) { 2192 if ((lr = p.left = l.right) != null) 2193 lr.parent = p; 2194 if ((pp = l.parent = p.parent) == null) 2195 (root = l).red = false; 2196 else if (pp.right == p) 2197 pp.right = l; 2198 else 2199 pp.left = l; 2200 l.right = p; 2201 p.parent = l; 2202 } 2203 return root; 2204 } 2205 2206 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root, 2207 TreeNode<K,V> x) { 2208 x.red = true; 2209 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) { 2210 if ((xp = x.parent) == null) { 2211 x.red = false; 2212 return x; 2213 } 2214 else if (!xp.red || (xpp = xp.parent) == null) 2215 return root; 2216 if (xp == (xppl = xpp.left)) { 2217 if ((xppr = xpp.right) != null && xppr.red) { 2218 xppr.red = false; 2219 xp.red = false; 2220 xpp.red = true; 2221 x = xpp; 2222 } 2223 else { 2224 if (x == xp.right) { 2225 root = rotateLeft(root, x = xp); 2226 xpp = (xp = x.parent) == null ? null : xp.parent; 2227 } 2228 if (xp != null) { 2229 xp.red = false; 2230 if (xpp != null) { 2231 xpp.red = true; 2232 root = rotateRight(root, xpp); 2233 } 2234 } 2235 } 2236 } 2237 else { 2238 if (xppl != null && xppl.red) { 2239 xppl.red = false; 2240 xp.red = false; 2241 xpp.red = true; 2242 x = xpp; 2243 } 2244 else { 2245 if (x == xp.left) { 2246 root = rotateRight(root, x = xp); 2247 xpp = (xp = x.parent) == null ? null : xp.parent; 2248 } 2249 if (xp != null) { 2250 xp.red = false; 2251 if (xpp != null) { 2252 xpp.red = true; 2253 root = rotateLeft(root, xpp); 2254 } 2255 } 2256 } 2257 } 2258 } 2259 } 2260 2261 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root, 2262 TreeNode<K,V> x) { 2263 for (TreeNode<K,V> xp, xpl, xpr;;) { 2264 if (x == null || x == root) 2265 return root; 2266 else if ((xp = x.parent) == null) { 2267 x.red = false; 2268 return x; 2269 } 2270 else if (x.red) { 2271 x.red = false; 2272 return root; 2273 } 2274 else if ((xpl = xp.left) == x) { 2275 if ((xpr = xp.right) != null && xpr.red) { 2276 xpr.red = false; 2277 xp.red = true; 2278 root = rotateLeft(root, xp); 2279 xpr = (xp = x.parent) == null ? null : xp.right; 2280 } 2281 if (xpr == null) 2282 x = xp; 2283 else { 2284 TreeNode<K,V> sl = xpr.left, sr = xpr.right; 2285 if ((sr == null || !sr.red) && 2286 (sl == null || !sl.red)) { 2287 xpr.red = true; 2288 x = xp; 2289 } 2290 else { 2291 if (sr == null || !sr.red) { 2292 if (sl != null) 2293 sl.red = false; 2294 xpr.red = true; 2295 root = rotateRight(root, xpr); 2296 xpr = (xp = x.parent) == null ? 2297 null : xp.right; 2298 } 2299 if (xpr != null) { 2300 xpr.red = (xp == null) ? false : xp.red; 2301 if ((sr = xpr.right) != null) 2302 sr.red = false; 2303 } 2304 if (xp != null) { 2305 xp.red = false; 2306 root = rotateLeft(root, xp); 2307 } 2308 x = root; 2309 } 2310 } 2311 } 2312 else { // symmetric 2313 if (xpl != null && xpl.red) { 2314 xpl.red = false; 2315 xp.red = true; 2316 root = rotateRight(root, xp); 2317 xpl = (xp = x.parent) == null ? null : xp.left; 2318 } 2319 if (xpl == null) 2320 x = xp; 2321 else { 2322 TreeNode<K,V> sl = xpl.left, sr = xpl.right; 2323 if ((sl == null || !sl.red) && 2324 (sr == null || !sr.red)) { 2325 xpl.red = true; 2326 x = xp; 2327 } 2328 else { 2329 if (sl == null || !sl.red) { 2330 if (sr != null) 2331 sr.red = false; 2332 xpl.red = true; 2333 root = rotateLeft(root, xpl); 2334 xpl = (xp = x.parent) == null ? 2335 null : xp.left; 2336 } 2337 if (xpl != null) { 2338 xpl.red = (xp == null) ? false : xp.red; 2339 if ((sl = xpl.left) != null) 2340 sl.red = false; 2341 } 2342 if (xp != null) { 2343 xp.red = false; 2344 root = rotateRight(root, xp); 2345 } 2346 x = root; 2347 } 2348 } 2349 } 2350 } 2351 } 2352 2353 /** 2354 * Recursive invariant check 2355 */ 2356 static <K,V> boolean checkInvariants(TreeNode<K,V> t) { 2357 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right, 2358 tb = t.prev, tn = (TreeNode<K,V>)t.next; 2359 if (tb != null && tb.next != t) 2360 return false; 2361 if (tn != null && tn.prev != t) 2362 return false; 2363 if (tp != null && t != tp.left && t != tp.right) 2364 return false; 2365 if (tl != null && (tl.parent != t || tl.hash > t.hash)) 2366 return false; 2367 if (tr != null && (tr.parent != t || tr.hash < t.hash)) 2368 return false; 2369 if (t.red && tl != null && tl.red && tr != null && tr.red) 2370 return false; 2371 if (tl != null && !checkInvariants(tl)) 2372 return false; 2373 if (tr != null && !checkInvariants(tr)) 2374 return false; 2375 return true; 2376 } 2377 } 2378 2379 }