--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/HashMap.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1055 @@
+/*
+ * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.util;
+import java.io.*;
+
+/**
+ * Hash table based implementation of the <tt>Map</tt> interface. This
+ * implementation provides all of the optional map operations, and permits
+ * <tt>null</tt> values and the <tt>null</tt> key. (The <tt>HashMap</tt>
+ * class is roughly equivalent to <tt>Hashtable</tt>, except that it is
+ * unsynchronized and permits nulls.) This class makes no guarantees as to
+ * the order of the map; in particular, it does not guarantee that the order
+ * will remain constant over time.
+ *
+ * <p>This implementation provides constant-time performance for the basic
+ * operations (<tt>get</tt> and <tt>put</tt>), assuming the hash function
+ * disperses the elements properly among the buckets. Iteration over
+ * collection views requires time proportional to the "capacity" of the
+ * <tt>HashMap</tt> instance (the number of buckets) plus its size (the number
+ * of key-value mappings). Thus, it's very important not to set the initial
+ * capacity too high (or the load factor too low) if iteration performance is
+ * important.
+ *
+ * <p>An instance of <tt>HashMap</tt> has two parameters that affect its
+ * performance: <i>initial capacity</i> and <i>load factor</i>. The
+ * <i>capacity</i> is the number of buckets in the hash table, and the initial
+ * capacity is simply the capacity at the time the hash table is created. The
+ * <i>load factor</i> is a measure of how full the hash table is allowed to
+ * get before its capacity is automatically increased. When the number of
+ * entries in the hash table exceeds the product of the load factor and the
+ * current capacity, the hash table is <i>rehashed</i> (that is, internal data
+ * structures are rebuilt) so that the hash table has approximately twice the
+ * number of buckets.
+ *
+ * <p>As a general rule, the default load factor (.75) offers a good tradeoff
+ * between time and space costs. Higher values decrease the space overhead
+ * but increase the lookup cost (reflected in most of the operations of the
+ * <tt>HashMap</tt> class, including <tt>get</tt> and <tt>put</tt>). The
+ * expected number of entries in the map and its load factor should be taken
+ * into account when setting its initial capacity, so as to minimize the
+ * number of rehash operations. If the initial capacity is greater
+ * than the maximum number of entries divided by the load factor, no
+ * rehash operations will ever occur.
+ *
+ * <p>If many mappings are to be stored in a <tt>HashMap</tt> instance,
+ * creating it with a sufficiently large capacity will allow the mappings to
+ * be stored more efficiently than letting it perform automatic rehashing as
+ * needed to grow the table.
+ *
+ * <p><strong>Note that this implementation is not synchronized.</strong>
+ * If multiple threads access a hash map concurrently, and at least one of
+ * the threads modifies the map structurally, it <i>must</i> be
+ * synchronized externally. (A structural modification is any operation
+ * that adds or deletes one or more mappings; merely changing the value
+ * associated with a key that an instance already contains is not a
+ * structural modification.) This is typically accomplished by
+ * synchronizing on some object that naturally encapsulates the map.
+ *
+ * If no such object exists, the map should be "wrapped" using the
+ * {@link Collections#synchronizedMap Collections.synchronizedMap}
+ * method. This is best done at creation time, to prevent accidental
+ * unsynchronized access to the map:<pre>
+ * Map m = Collections.synchronizedMap(new HashMap(...));</pre>
+ *
+ * <p>The iterators returned by all of this class's "collection view methods"
+ * are <i>fail-fast</i>: if the map is structurally modified at any time after
+ * the iterator is created, in any way except through the iterator's own
+ * <tt>remove</tt> method, the iterator will throw a
+ * {@link ConcurrentModificationException}. Thus, in the face of concurrent
+ * modification, the iterator fails quickly and cleanly, rather than risking
+ * arbitrary, non-deterministic behavior at an undetermined time in the
+ * future.
+ *
+ * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
+ * as it is, generally speaking, impossible to make any hard guarantees in the
+ * presence of unsynchronized concurrent modification. Fail-fast iterators
+ * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
+ * Therefore, it would be wrong to write a program that depended on this
+ * exception for its correctness: <i>the fail-fast behavior of iterators
+ * should be used only to detect bugs.</i>
+ *
+ * <p>This class is a member of the
+ * <a href="{@docRoot}/../technotes/guides/collections/index.html">
+ * Java Collections Framework</a>.
+ *
+ * @param <K> the type of keys maintained by this map
+ * @param <V> the type of mapped values
+ *
+ * @author Doug Lea
+ * @author Josh Bloch
+ * @author Arthur van Hoff
+ * @author Neal Gafter
+ * @see Object#hashCode()
+ * @see Collection
+ * @see Map
+ * @see TreeMap
+ * @see Hashtable
+ * @since 1.2
+ */
+
+public class HashMap<K,V>
+ extends AbstractMap<K,V>
+ implements Map<K,V>, Cloneable, Serializable
+{
+
+ /**
+ * The default initial capacity - MUST be a power of two.
+ */
+ static final int DEFAULT_INITIAL_CAPACITY = 16;
+
+ /**
+ * The maximum capacity, used if a higher value is implicitly specified
+ * by either of the constructors with arguments.
+ * MUST be a power of two <= 1<<30.
+ */
+ static final int MAXIMUM_CAPACITY = 1 << 30;
+
+ /**
+ * The load factor used when none specified in constructor.
+ */
+ static final float DEFAULT_LOAD_FACTOR = 0.75f;
+
+ /**
+ * The table, resized as necessary. Length MUST Always be a power of two.
+ */
+ transient Entry[] table;
+
+ /**
+ * The number of key-value mappings contained in this map.
+ */
+ transient int size;
+
+ /**
+ * The next size value at which to resize (capacity * load factor).
+ * @serial
+ */
+ int threshold;
+
+ /**
+ * The load factor for the hash table.
+ *
+ * @serial
+ */
+ final float loadFactor;
+
+ /**
+ * The number of times this HashMap has been structurally modified
+ * Structural modifications are those that change the number of mappings in
+ * the HashMap or otherwise modify its internal structure (e.g.,
+ * rehash). This field is used to make iterators on Collection-views of
+ * the HashMap fail-fast. (See ConcurrentModificationException).
+ */
+ transient volatile int modCount;
+
+ /**
+ * Constructs an empty <tt>HashMap</tt> with the specified initial
+ * capacity and load factor.
+ *
+ * @param initialCapacity the initial capacity
+ * @param loadFactor the load factor
+ * @throws IllegalArgumentException if the initial capacity is negative
+ * or the load factor is nonpositive
+ */
+ public HashMap(int initialCapacity, float loadFactor) {
+ if (initialCapacity < 0)
+ throw new IllegalArgumentException("Illegal initial capacity: " +
+ initialCapacity);
+ if (initialCapacity > MAXIMUM_CAPACITY)
+ initialCapacity = MAXIMUM_CAPACITY;
+ if (loadFactor <= 0 || Float.isNaN(loadFactor))
+ throw new IllegalArgumentException("Illegal load factor: " +
+ loadFactor);
+
+ // Find a power of 2 >= initialCapacity
+ int capacity = 1;
+ while (capacity < initialCapacity)
+ capacity <<= 1;
+
+ this.loadFactor = loadFactor;
+ threshold = (int)(capacity * loadFactor);
+ table = new Entry[capacity];
+ init();
+ }
+
+ /**
+ * Constructs an empty <tt>HashMap</tt> with the specified initial
+ * capacity and the default load factor (0.75).
+ *
+ * @param initialCapacity the initial capacity.
+ * @throws IllegalArgumentException if the initial capacity is negative.
+ */
+ public HashMap(int initialCapacity) {
+ this(initialCapacity, DEFAULT_LOAD_FACTOR);
+ }
+
+ /**
+ * Constructs an empty <tt>HashMap</tt> with the default initial capacity
+ * (16) and the default load factor (0.75).
+ */
+ public HashMap() {
+ this.loadFactor = DEFAULT_LOAD_FACTOR;
+ threshold = (int)(DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
+ table = new Entry[DEFAULT_INITIAL_CAPACITY];
+ init();
+ }
+
+ /**
+ * Constructs a new <tt>HashMap</tt> with the same mappings as the
+ * specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
+ * default load factor (0.75) and an initial capacity sufficient to
+ * hold the mappings in the specified <tt>Map</tt>.
+ *
+ * @param m the map whose mappings are to be placed in this map
+ * @throws NullPointerException if the specified map is null
+ */
+ public HashMap(Map<? extends K, ? extends V> m) {
+ this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
+ DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR);
+ putAllForCreate(m);
+ }
+
+ // internal utilities
+
+ /**
+ * Initialization hook for subclasses. This method is called
+ * in all constructors and pseudo-constructors (clone, readObject)
+ * after HashMap has been initialized but before any entries have
+ * been inserted. (In the absence of this method, readObject would
+ * require explicit knowledge of subclasses.)
+ */
+ void init() {
+ }
+
+ /**
+ * Applies a supplemental hash function to a given hashCode, which
+ * defends against poor quality hash functions. This is critical
+ * because HashMap uses power-of-two length hash tables, that
+ * otherwise encounter collisions for hashCodes that do not differ
+ * in lower bits. Note: Null keys always map to hash 0, thus index 0.
+ */
+ static int hash(int h) {
+ // This function ensures that hashCodes that differ only by
+ // constant multiples at each bit position have a bounded
+ // number of collisions (approximately 8 at default load factor).
+ h ^= (h >>> 20) ^ (h >>> 12);
+ return h ^ (h >>> 7) ^ (h >>> 4);
+ }
+
+ /**
+ * Returns index for hash code h.
+ */
+ static int indexFor(int h, int length) {
+ return h & (length-1);
+ }
+
+ /**
+ * Returns the number of key-value mappings in this map.
+ *
+ * @return the number of key-value mappings in this map
+ */
+ public int size() {
+ return size;
+ }
+
+ /**
+ * Returns <tt>true</tt> if this map contains no key-value mappings.
+ *
+ * @return <tt>true</tt> if this map contains no key-value mappings
+ */
+ public boolean isEmpty() {
+ return size == 0;
+ }
+
+ /**
+ * Returns the value to which the specified key is mapped,
+ * or {@code null} if this map contains no mapping for the key.
+ *
+ * <p>More formally, if this map contains a mapping from a key
+ * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
+ * key.equals(k))}, then this method returns {@code v}; otherwise
+ * it returns {@code null}. (There can be at most one such mapping.)
+ *
+ * <p>A return value of {@code null} does not <i>necessarily</i>
+ * indicate that the map contains no mapping for the key; it's also
+ * possible that the map explicitly maps the key to {@code null}.
+ * The {@link #containsKey containsKey} operation may be used to
+ * distinguish these two cases.
+ *
+ * @see #put(Object, Object)
+ */
+ public V get(Object key) {
+ if (key == null)
+ return getForNullKey();
+ int hash = hash(key.hashCode());
+ for (Entry<K,V> e = table[indexFor(hash, table.length)];
+ e != null;
+ e = e.next) {
+ Object k;
+ if (e.hash == hash && ((k = e.key) == key || key.equals(k)))
+ return e.value;
+ }
+ return null;
+ }
+
+ /**
+ * Offloaded version of get() to look up null keys. Null keys map
+ * to index 0. This null case is split out into separate methods
+ * for the sake of performance in the two most commonly used
+ * operations (get and put), but incorporated with conditionals in
+ * others.
+ */
+ private V getForNullKey() {
+ for (Entry<K,V> e = table[0]; e != null; e = e.next) {
+ if (e.key == null)
+ return e.value;
+ }
+ return null;
+ }
+
+ /**
+ * Returns <tt>true</tt> if this map contains a mapping for the
+ * specified key.
+ *
+ * @param key The key whose presence in this map is to be tested
+ * @return <tt>true</tt> if this map contains a mapping for the specified
+ * key.
+ */
+ public boolean containsKey(Object key) {
+ return getEntry(key) != null;
+ }
+
+ /**
+ * Returns the entry associated with the specified key in the
+ * HashMap. Returns null if the HashMap contains no mapping
+ * for the key.
+ */
+ final Entry<K,V> getEntry(Object key) {
+ int hash = (key == null) ? 0 : hash(key.hashCode());
+ for (Entry<K,V> e = table[indexFor(hash, table.length)];
+ e != null;
+ e = e.next) {
+ Object k;
+ if (e.hash == hash &&
+ ((k = e.key) == key || (key != null && key.equals(k))))
+ return e;
+ }
+ return null;
+ }
+
+
+ /**
+ * Associates the specified value with the specified key in this map.
+ * If the map previously contained a mapping for the key, the old
+ * value is replaced.
+ *
+ * @param key key with which the specified value is to be associated
+ * @param value value to be associated with the specified key
+ * @return the previous value associated with <tt>key</tt>, or
+ * <tt>null</tt> if there was no mapping for <tt>key</tt>.
+ * (A <tt>null</tt> return can also indicate that the map
+ * previously associated <tt>null</tt> with <tt>key</tt>.)
+ */
+ public V put(K key, V value) {
+ if (key == null)
+ return putForNullKey(value);
+ int hash = hash(key.hashCode());
+ int i = indexFor(hash, table.length);
+ for (Entry<K,V> e = table[i]; e != null; e = e.next) {
+ Object k;
+ if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
+ V oldValue = e.value;
+ e.value = value;
+ e.recordAccess(this);
+ return oldValue;
+ }
+ }
+
+ modCount++;
+ addEntry(hash, key, value, i);
+ return null;
+ }
+
+ /**
+ * Offloaded version of put for null keys
+ */
+ private V putForNullKey(V value) {
+ for (Entry<K,V> e = table[0]; e != null; e = e.next) {
+ if (e.key == null) {
+ V oldValue = e.value;
+ e.value = value;
+ e.recordAccess(this);
+ return oldValue;
+ }
+ }
+ modCount++;
+ addEntry(0, null, value, 0);
+ return null;
+ }
+
+ /**
+ * This method is used instead of put by constructors and
+ * pseudoconstructors (clone, readObject). It does not resize the table,
+ * check for comodification, etc. It calls createEntry rather than
+ * addEntry.
+ */
+ private void putForCreate(K key, V value) {
+ int hash = (key == null) ? 0 : hash(key.hashCode());
+ int i = indexFor(hash, table.length);
+
+ /**
+ * Look for preexisting entry for key. This will never happen for
+ * clone or deserialize. It will only happen for construction if the
+ * input Map is a sorted map whose ordering is inconsistent w/ equals.
+ */
+ for (Entry<K,V> e = table[i]; e != null; e = e.next) {
+ Object k;
+ if (e.hash == hash &&
+ ((k = e.key) == key || (key != null && key.equals(k)))) {
+ e.value = value;
+ return;
+ }
+ }
+
+ createEntry(hash, key, value, i);
+ }
+
+ private void putAllForCreate(Map<? extends K, ? extends V> m) {
+ for (Iterator<? extends Map.Entry<? extends K, ? extends V>> i = m.entrySet().iterator(); i.hasNext(); ) {
+ Map.Entry<? extends K, ? extends V> e = i.next();
+ putForCreate(e.getKey(), e.getValue());
+ }
+ }
+
+ /**
+ * Rehashes the contents of this map into a new array with a
+ * larger capacity. This method is called automatically when the
+ * number of keys in this map reaches its threshold.
+ *
+ * If current capacity is MAXIMUM_CAPACITY, this method does not
+ * resize the map, but sets threshold to Integer.MAX_VALUE.
+ * This has the effect of preventing future calls.
+ *
+ * @param newCapacity the new capacity, MUST be a power of two;
+ * must be greater than current capacity unless current
+ * capacity is MAXIMUM_CAPACITY (in which case value
+ * is irrelevant).
+ */
+ void resize(int newCapacity) {
+ Entry[] oldTable = table;
+ int oldCapacity = oldTable.length;
+ if (oldCapacity == MAXIMUM_CAPACITY) {
+ threshold = Integer.MAX_VALUE;
+ return;
+ }
+
+ Entry[] newTable = new Entry[newCapacity];
+ transfer(newTable);
+ table = newTable;
+ threshold = (int)(newCapacity * loadFactor);
+ }
+
+ /**
+ * Transfers all entries from current table to newTable.
+ */
+ void transfer(Entry[] newTable) {
+ Entry[] src = table;
+ int newCapacity = newTable.length;
+ for (int j = 0; j < src.length; j++) {
+ Entry<K,V> e = src[j];
+ if (e != null) {
+ src[j] = null;
+ do {
+ Entry<K,V> next = e.next;
+ int i = indexFor(e.hash, newCapacity);
+ e.next = newTable[i];
+ newTable[i] = e;
+ e = next;
+ } while (e != null);
+ }
+ }
+ }
+
+ /**
+ * Copies all of the mappings from the specified map to this map.
+ * These mappings will replace any mappings that this map had for
+ * any of the keys currently in the specified map.
+ *
+ * @param m mappings to be stored in this map
+ * @throws NullPointerException if the specified map is null
+ */
+ public void putAll(Map<? extends K, ? extends V> m) {
+ int numKeysToBeAdded = m.size();
+ if (numKeysToBeAdded == 0)
+ return;
+
+ /*
+ * Expand the map if the map if the number of mappings to be added
+ * is greater than or equal to threshold. This is conservative; the
+ * obvious condition is (m.size() + size) >= threshold, but this
+ * condition could result in a map with twice the appropriate capacity,
+ * if the keys to be added overlap with the keys already in this map.
+ * By using the conservative calculation, we subject ourself
+ * to at most one extra resize.
+ */
+ if (numKeysToBeAdded > threshold) {
+ int targetCapacity = (int)(numKeysToBeAdded / loadFactor + 1);
+ if (targetCapacity > MAXIMUM_CAPACITY)
+ targetCapacity = MAXIMUM_CAPACITY;
+ int newCapacity = table.length;
+ while (newCapacity < targetCapacity)
+ newCapacity <<= 1;
+ if (newCapacity > table.length)
+ resize(newCapacity);
+ }
+
+ for (Iterator<? extends Map.Entry<? extends K, ? extends V>> i = m.entrySet().iterator(); i.hasNext(); ) {
+ Map.Entry<? extends K, ? extends V> e = i.next();
+ put(e.getKey(), e.getValue());
+ }
+ }
+
+ /**
+ * Removes the mapping for the specified key from this map if present.
+ *
+ * @param key key whose mapping is to be removed from the map
+ * @return the previous value associated with <tt>key</tt>, or
+ * <tt>null</tt> if there was no mapping for <tt>key</tt>.
+ * (A <tt>null</tt> return can also indicate that the map
+ * previously associated <tt>null</tt> with <tt>key</tt>.)
+ */
+ public V remove(Object key) {
+ Entry<K,V> e = removeEntryForKey(key);
+ return (e == null ? null : e.value);
+ }
+
+ /**
+ * Removes and returns the entry associated with the specified key
+ * in the HashMap. Returns null if the HashMap contains no mapping
+ * for this key.
+ */
+ final Entry<K,V> removeEntryForKey(Object key) {
+ int hash = (key == null) ? 0 : hash(key.hashCode());
+ int i = indexFor(hash, table.length);
+ Entry<K,V> prev = table[i];
+ Entry<K,V> e = prev;
+
+ while (e != null) {
+ Entry<K,V> next = e.next;
+ Object k;
+ if (e.hash == hash &&
+ ((k = e.key) == key || (key != null && key.equals(k)))) {
+ modCount++;
+ size--;
+ if (prev == e)
+ table[i] = next;
+ else
+ prev.next = next;
+ e.recordRemoval(this);
+ return e;
+ }
+ prev = e;
+ e = next;
+ }
+
+ return e;
+ }
+
+ /**
+ * Special version of remove for EntrySet.
+ */
+ final Entry<K,V> removeMapping(Object o) {
+ if (!(o instanceof Map.Entry))
+ return null;
+
+ Map.Entry<K,V> entry = (Map.Entry<K,V>) o;
+ Object key = entry.getKey();
+ int hash = (key == null) ? 0 : hash(key.hashCode());
+ int i = indexFor(hash, table.length);
+ Entry<K,V> prev = table[i];
+ Entry<K,V> e = prev;
+
+ while (e != null) {
+ Entry<K,V> next = e.next;
+ if (e.hash == hash && e.equals(entry)) {
+ modCount++;
+ size--;
+ if (prev == e)
+ table[i] = next;
+ else
+ prev.next = next;
+ e.recordRemoval(this);
+ return e;
+ }
+ prev = e;
+ e = next;
+ }
+
+ return e;
+ }
+
+ /**
+ * Removes all of the mappings from this map.
+ * The map will be empty after this call returns.
+ */
+ public void clear() {
+ modCount++;
+ Entry[] tab = table;
+ for (int i = 0; i < tab.length; i++)
+ tab[i] = null;
+ size = 0;
+ }
+
+ /**
+ * Returns <tt>true</tt> if this map maps one or more keys to the
+ * specified value.
+ *
+ * @param value value whose presence in this map is to be tested
+ * @return <tt>true</tt> if this map maps one or more keys to the
+ * specified value
+ */
+ public boolean containsValue(Object value) {
+ if (value == null)
+ return containsNullValue();
+
+ Entry[] tab = table;
+ for (int i = 0; i < tab.length ; i++)
+ for (Entry e = tab[i] ; e != null ; e = e.next)
+ if (value.equals(e.value))
+ return true;
+ return false;
+ }
+
+ /**
+ * Special-case code for containsValue with null argument
+ */
+ private boolean containsNullValue() {
+ Entry[] tab = table;
+ for (int i = 0; i < tab.length ; i++)
+ for (Entry e = tab[i] ; e != null ; e = e.next)
+ if (e.value == null)
+ return true;
+ return false;
+ }
+
+ /**
+ * Returns a shallow copy of this <tt>HashMap</tt> instance: the keys and
+ * values themselves are not cloned.
+ *
+ * @return a shallow copy of this map
+ */
+ public Object clone() {
+ HashMap<K,V> result = null;
+ try {
+ result = (HashMap<K,V>)super.clone();
+ } catch (CloneNotSupportedException e) {
+ // assert false;
+ }
+ result.table = new Entry[table.length];
+ result.entrySet = null;
+ result.modCount = 0;
+ result.size = 0;
+ result.init();
+ result.putAllForCreate(this);
+
+ return result;
+ }
+
+ static class Entry<K,V> implements Map.Entry<K,V> {
+ final K key;
+ V value;
+ Entry<K,V> next;
+ final int hash;
+
+ /**
+ * Creates new entry.
+ */
+ Entry(int h, K k, V v, Entry<K,V> n) {
+ value = v;
+ next = n;
+ key = k;
+ hash = h;
+ }
+
+ public final K getKey() {
+ return key;
+ }
+
+ public final V getValue() {
+ return value;
+ }
+
+ public final V setValue(V newValue) {
+ V oldValue = value;
+ value = newValue;
+ return oldValue;
+ }
+
+ public final boolean equals(Object o) {
+ if (!(o instanceof Map.Entry))
+ return false;
+ Map.Entry e = (Map.Entry)o;
+ Object k1 = getKey();
+ Object k2 = e.getKey();
+ if (k1 == k2 || (k1 != null && k1.equals(k2))) {
+ Object v1 = getValue();
+ Object v2 = e.getValue();
+ if (v1 == v2 || (v1 != null && v1.equals(v2)))
+ return true;
+ }
+ return false;
+ }
+
+ public final int hashCode() {
+ return (key==null ? 0 : key.hashCode()) ^
+ (value==null ? 0 : value.hashCode());
+ }
+
+ public final String toString() {
+ return getKey() + "=" + getValue();
+ }
+
+ /**
+ * This method is invoked whenever the value in an entry is
+ * overwritten by an invocation of put(k,v) for a key k that's already
+ * in the HashMap.
+ */
+ void recordAccess(HashMap<K,V> m) {
+ }
+
+ /**
+ * This method is invoked whenever the entry is
+ * removed from the table.
+ */
+ void recordRemoval(HashMap<K,V> m) {
+ }
+ }
+
+ /**
+ * Adds a new entry with the specified key, value and hash code to
+ * the specified bucket. It is the responsibility of this
+ * method to resize the table if appropriate.
+ *
+ * Subclass overrides this to alter the behavior of put method.
+ */
+ void addEntry(int hash, K key, V value, int bucketIndex) {
+ Entry<K,V> e = table[bucketIndex];
+ table[bucketIndex] = new Entry<K,V>(hash, key, value, e);
+ if (size++ >= threshold)
+ resize(2 * table.length);
+ }
+
+ /**
+ * Like addEntry except that this version is used when creating entries
+ * as part of Map construction or "pseudo-construction" (cloning,
+ * deserialization). This version needn't worry about resizing the table.
+ *
+ * Subclass overrides this to alter the behavior of HashMap(Map),
+ * clone, and readObject.
+ */
+ void createEntry(int hash, K key, V value, int bucketIndex) {
+ Entry<K,V> e = table[bucketIndex];
+ table[bucketIndex] = new Entry<K,V>(hash, key, value, e);
+ size++;
+ }
+
+ private abstract class HashIterator<E> implements Iterator<E> {
+ Entry<K,V> next; // next entry to return
+ int expectedModCount; // For fast-fail
+ int index; // current slot
+ Entry<K,V> current; // current entry
+
+ HashIterator() {
+ expectedModCount = modCount;
+ if (size > 0) { // advance to first entry
+ Entry[] t = table;
+ while (index < t.length && (next = t[index++]) == null)
+ ;
+ }
+ }
+
+ public final boolean hasNext() {
+ return next != null;
+ }
+
+ final Entry<K,V> nextEntry() {
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ Entry<K,V> e = next;
+ if (e == null)
+ throw new NoSuchElementException();
+
+ if ((next = e.next) == null) {
+ Entry[] t = table;
+ while (index < t.length && (next = t[index++]) == null)
+ ;
+ }
+ current = e;
+ return e;
+ }
+
+ public void remove() {
+ if (current == null)
+ throw new IllegalStateException();
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ Object k = current.key;
+ current = null;
+ HashMap.this.removeEntryForKey(k);
+ expectedModCount = modCount;
+ }
+
+ }
+
+ private final class ValueIterator extends HashIterator<V> {
+ public V next() {
+ return nextEntry().value;
+ }
+ }
+
+ private final class KeyIterator extends HashIterator<K> {
+ public K next() {
+ return nextEntry().getKey();
+ }
+ }
+
+ private final class EntryIterator extends HashIterator<Map.Entry<K,V>> {
+ public Map.Entry<K,V> next() {
+ return nextEntry();
+ }
+ }
+
+ // Subclass overrides these to alter behavior of views' iterator() method
+ Iterator<K> newKeyIterator() {
+ return new KeyIterator();
+ }
+ Iterator<V> newValueIterator() {
+ return new ValueIterator();
+ }
+ Iterator<Map.Entry<K,V>> newEntryIterator() {
+ return new EntryIterator();
+ }
+
+
+ // Views
+
+ private transient Set<Map.Entry<K,V>> entrySet = null;
+
+ /**
+ * Returns a {@link Set} view of the keys contained in this map.
+ * The set is backed by the map, so changes to the map are
+ * reflected in the set, and vice-versa. If the map is modified
+ * while an iteration over the set is in progress (except through
+ * the iterator's own <tt>remove</tt> operation), the results of
+ * the iteration are undefined. The set supports element removal,
+ * which removes the corresponding mapping from the map, via the
+ * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
+ * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
+ * operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
+ * operations.
+ */
+ public Set<K> keySet() {
+ Set<K> ks = keySet;
+ return (ks != null ? ks : (keySet = new KeySet()));
+ }
+
+ private final class KeySet extends AbstractSet<K> {
+ public Iterator<K> iterator() {
+ return newKeyIterator();
+ }
+ public int size() {
+ return size;
+ }
+ public boolean contains(Object o) {
+ return containsKey(o);
+ }
+ public boolean remove(Object o) {
+ return HashMap.this.removeEntryForKey(o) != null;
+ }
+ public void clear() {
+ HashMap.this.clear();
+ }
+ }
+
+ /**
+ * Returns a {@link Collection} view of the values contained in this map.
+ * The collection is backed by the map, so changes to the map are
+ * reflected in the collection, and vice-versa. If the map is
+ * modified while an iteration over the collection is in progress
+ * (except through the iterator's own <tt>remove</tt> operation),
+ * the results of the iteration are undefined. The collection
+ * supports element removal, which removes the corresponding
+ * mapping from the map, via the <tt>Iterator.remove</tt>,
+ * <tt>Collection.remove</tt>, <tt>removeAll</tt>,
+ * <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
+ * support the <tt>add</tt> or <tt>addAll</tt> operations.
+ */
+ public Collection<V> values() {
+ Collection<V> vs = values;
+ return (vs != null ? vs : (values = new Values()));
+ }
+
+ private final class Values extends AbstractCollection<V> {
+ public Iterator<V> iterator() {
+ return newValueIterator();
+ }
+ public int size() {
+ return size;
+ }
+ public boolean contains(Object o) {
+ return containsValue(o);
+ }
+ public void clear() {
+ HashMap.this.clear();
+ }
+ }
+
+ /**
+ * Returns a {@link Set} view of the mappings contained in this map.
+ * The set is backed by the map, so changes to the map are
+ * reflected in the set, and vice-versa. If the map is modified
+ * while an iteration over the set is in progress (except through
+ * the iterator's own <tt>remove</tt> operation, or through the
+ * <tt>setValue</tt> operation on a map entry returned by the
+ * iterator) the results of the iteration are undefined. The set
+ * supports element removal, which removes the corresponding
+ * mapping from the map, via the <tt>Iterator.remove</tt>,
+ * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
+ * <tt>clear</tt> operations. It does not support the
+ * <tt>add</tt> or <tt>addAll</tt> operations.
+ *
+ * @return a set view of the mappings contained in this map
+ */
+ public Set<Map.Entry<K,V>> entrySet() {
+ return entrySet0();
+ }
+
+ private Set<Map.Entry<K,V>> entrySet0() {
+ Set<Map.Entry<K,V>> es = entrySet;
+ return es != null ? es : (entrySet = new EntrySet());
+ }
+
+ private final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
+ public Iterator<Map.Entry<K,V>> iterator() {
+ return newEntryIterator();
+ }
+ public boolean contains(Object o) {
+ if (!(o instanceof Map.Entry))
+ return false;
+ Map.Entry<K,V> e = (Map.Entry<K,V>) o;
+ Entry<K,V> candidate = getEntry(e.getKey());
+ return candidate != null && candidate.equals(e);
+ }
+ public boolean remove(Object o) {
+ return removeMapping(o) != null;
+ }
+ public int size() {
+ return size;
+ }
+ public void clear() {
+ HashMap.this.clear();
+ }
+ }
+
+ /**
+ * Save the state of the <tt>HashMap</tt> instance to a stream (i.e.,
+ * serialize it).
+ *
+ * @serialData The <i>capacity</i> of the HashMap (the length of the
+ * bucket array) is emitted (int), followed by the
+ * <i>size</i> (an int, the number of key-value
+ * mappings), followed by the key (Object) and value (Object)
+ * for each key-value mapping. The key-value mappings are
+ * emitted in no particular order.
+ */
+ private void writeObject(java.io.ObjectOutputStream s)
+ throws IOException
+ {
+ Iterator<Map.Entry<K,V>> i =
+ (size > 0) ? entrySet0().iterator() : null;
+
+ // Write out the threshold, loadfactor, and any hidden stuff
+ s.defaultWriteObject();
+
+ // Write out number of buckets
+ s.writeInt(table.length);
+
+ // Write out size (number of Mappings)
+ s.writeInt(size);
+
+ // Write out keys and values (alternating)
+ if (i != null) {
+ while (i.hasNext()) {
+ Map.Entry<K,V> e = i.next();
+ s.writeObject(e.getKey());
+ s.writeObject(e.getValue());
+ }
+ }
+ }
+
+ private static final long serialVersionUID = 362498820763181265L;
+
+ /**
+ * Reconstitute the <tt>HashMap</tt> instance from a stream (i.e.,
+ * deserialize it).
+ */
+ private void readObject(java.io.ObjectInputStream s)
+ throws IOException, ClassNotFoundException
+ {
+ // Read in the threshold, loadfactor, and any hidden stuff
+ s.defaultReadObject();
+
+ // Read in number of buckets and allocate the bucket array;
+ int numBuckets = s.readInt();
+ table = new Entry[numBuckets];
+
+ init(); // Give subclass a chance to do its thing.
+
+ // Read in size (number of Mappings)
+ int size = s.readInt();
+
+ // Read the keys and values, and put the mappings in the HashMap
+ for (int i=0; i<size; i++) {
+ K key = (K) s.readObject();
+ V value = (V) s.readObject();
+ putForCreate(key, value);
+ }
+ }
+
+ // These methods are used when serializing HashSets
+ int capacity() { return table.length; }
+ float loadFactor() { return loadFactor; }
+}