| /* |
| * Copyright (C) 2012 The Guava Authors |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.common.collect; |
| |
| import static com.google.common.collect.CollectPreconditions.checkRemove; |
| import static com.google.common.collect.Hashing.smearedHash; |
| |
| import com.google.common.annotations.GwtIncompatible; |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Objects; |
| import com.google.common.base.Preconditions; |
| import com.google.errorprone.annotations.CanIgnoreReturnValue; |
| import com.google.j2objc.annotations.WeakOuter; |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.io.Serializable; |
| import java.util.AbstractCollection; |
| import java.util.AbstractMap; |
| import java.util.AbstractSet; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.ConcurrentModificationException; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| import java.util.Set; |
| import org.checkerframework.checker.nullness.compatqual.MonotonicNonNullDecl; |
| import org.checkerframework.checker.nullness.compatqual.NullableDecl; |
| |
| /** |
| * CompactHashMap is an implementation of a Map. All optional operations (put and remove) are |
| * supported. Null keys and values are supported. |
| * |
| * <p>{@code containsKey(k)}, {@code put(k, v)} and {@code remove(k)} are all (expected and |
| * amortized) constant time operations. Expected in the hashtable sense (depends on the hash |
| * function doing a good job of distributing the elements to the buckets to a distribution not far |
| * from uniform), and amortized since some operations can trigger a hash table resize. |
| * |
| * <p>Unlike {@code java.util.HashMap}, iteration is only proportional to the actual {@code size()}, |
| * which is optimal, and <i>not</i> the size of the internal hashtable, which could be much larger |
| * than {@code size()}. Furthermore, this structure places significantly reduced load on the garbage |
| * collector by only using a constant number of internal objects. |
| * |
| * <p>If there are no removals, then iteration order for the {@link #entrySet}, {@link #keySet}, and |
| * {@link #values} views is the same as insertion order. Any removal invalidates any ordering |
| * guarantees. |
| * |
| * <p>This class should not be assumed to be universally superior to {@code java.util.HashMap}. |
| * Generally speaking, this class reduces object allocation and memory consumption at the price of |
| * moderately increased constant factors of CPU. Only use this class when there is a specific reason |
| * to prioritize memory over CPU. |
| * |
| * @author Louis Wasserman |
| */ |
| @GwtIncompatible // not worth using in GWT for now |
| class CompactHashMap<K, V> extends AbstractMap<K, V> implements Serializable { |
| /* |
| * TODO: Make this a drop-in replacement for j.u. versions, actually drop them in, and test the |
| * world. Figure out what sort of space-time tradeoff we're actually going to get here with the |
| * *Map variants. Followon optimizations, such as using 16-bit indices for small collections, will |
| * take more work to implement. This class is particularly hard to benchmark, because the benefit |
| * is not only in less allocation, but also having the GC do less work to scan the heap because of |
| * fewer references, which is particularly hard to quantify. |
| */ |
| |
| /** Creates an empty {@code CompactHashMap} instance. */ |
| public static <K, V> CompactHashMap<K, V> create() { |
| return new CompactHashMap<>(); |
| } |
| |
| /** |
| * Creates a {@code CompactHashMap} instance, with a high enough "initial capacity" that it |
| * <i>should</i> hold {@code expectedSize} elements without growth. |
| * |
| * @param expectedSize the number of elements you expect to add to the returned set |
| * @return a new, empty {@code CompactHashMap} with enough capacity to hold {@code expectedSize} |
| * elements without resizing |
| * @throws IllegalArgumentException if {@code expectedSize} is negative |
| */ |
| public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSize) { |
| return new CompactHashMap<>(expectedSize); |
| } |
| |
| private static final int MAXIMUM_CAPACITY = 1 << 30; |
| |
| // TODO(user): decide, and inline, load factor. 0.75? |
| static final float DEFAULT_LOAD_FACTOR = 1.0f; |
| |
| /** Bitmask that selects the low 32 bits. */ |
| private static final long NEXT_MASK = (1L << 32) - 1; |
| |
| /** Bitmask that selects the high 32 bits. */ |
| private static final long HASH_MASK = ~NEXT_MASK; |
| |
| // TODO(user): decide default size |
| static final int DEFAULT_SIZE = 3; |
| |
| // used to indicate blank table entries |
| static final int UNSET = -1; |
| |
| /** |
| * The hashtable. Its values are indexes to the keys, values, and entries arrays. |
| * |
| * <p>Currently, the UNSET value means "null pointer", and any non negative value x is the actual |
| * index. |
| * |
| * <p>Its size must be a power of two. |
| */ |
| @MonotonicNonNullDecl private transient int[] table; |
| |
| /** |
| * Contains the logical entries, in the range of [0, size()). The high 32 bits of each long is the |
| * smeared hash of the element, whereas the low 32 bits is the "next" pointer (pointing to the |
| * next entry in the bucket chain). The pointers in [size(), entries.length) are all "null" |
| * (UNSET). |
| */ |
| @VisibleForTesting @MonotonicNonNullDecl transient long[] entries; |
| |
| /** |
| * The keys of the entries in the map, in the range of [0, size()). The keys in [size(), |
| * keys.length) are all {@code null}. |
| */ |
| @VisibleForTesting @MonotonicNonNullDecl transient Object[] keys; |
| |
| /** |
| * The values of the entries in the map, in the range of [0, size()). The values in [size(), |
| * values.length) are all {@code null}. |
| */ |
| @VisibleForTesting @MonotonicNonNullDecl transient Object[] values; |
| |
| /** The load factor. */ |
| transient float loadFactor; |
| |
| /** |
| * Keeps track of modifications of this set, to make it possible to throw |
| * ConcurrentModificationException in the iterator. Note that we choose not to make this volatile, |
| * so we do less of a "best effort" to track such errors, for better performance. |
| */ |
| transient int modCount; |
| |
| /** When we have this many elements, resize the hashtable. */ |
| private transient int threshold; |
| |
| /** The number of elements contained in the set. */ |
| private transient int size; |
| |
| /** Constructs a new empty instance of {@code CompactHashMap}. */ |
| CompactHashMap() { |
| init(DEFAULT_SIZE, DEFAULT_LOAD_FACTOR); |
| } |
| |
| /** |
| * Constructs a new instance of {@code CompactHashMap} with the specified capacity. |
| * |
| * @param capacity the initial capacity of this {@code CompactHashMap}. |
| */ |
| CompactHashMap(int capacity) { |
| this(capacity, DEFAULT_LOAD_FACTOR); |
| } |
| |
| CompactHashMap(int expectedSize, float loadFactor) { |
| init(expectedSize, loadFactor); |
| } |
| |
| /** Pseudoconstructor for serialization support. */ |
| void init(int expectedSize, float loadFactor) { |
| Preconditions.checkArgument(expectedSize >= 0, "Initial capacity must be non-negative"); |
| Preconditions.checkArgument(loadFactor > 0, "Illegal load factor"); |
| int buckets = Hashing.closedTableSize(expectedSize, loadFactor); |
| this.table = newTable(buckets); |
| this.loadFactor = loadFactor; |
| |
| this.keys = new Object[expectedSize]; |
| this.values = new Object[expectedSize]; |
| |
| this.entries = newEntries(expectedSize); |
| this.threshold = Math.max(1, (int) (buckets * loadFactor)); |
| } |
| |
| private static int[] newTable(int size) { |
| int[] array = new int[size]; |
| Arrays.fill(array, UNSET); |
| return array; |
| } |
| |
| private static long[] newEntries(int size) { |
| long[] array = new long[size]; |
| Arrays.fill(array, UNSET); |
| return array; |
| } |
| |
| private int hashTableMask() { |
| return table.length - 1; |
| } |
| |
| private static int getHash(long entry) { |
| return (int) (entry >>> 32); |
| } |
| |
| /** Returns the index, or UNSET if the pointer is "null" */ |
| private static int getNext(long entry) { |
| return (int) entry; |
| } |
| |
| /** Returns a new entry value by changing the "next" index of an existing entry */ |
| private static long swapNext(long entry, int newNext) { |
| return (HASH_MASK & entry) | (NEXT_MASK & newNext); |
| } |
| |
| /** |
| * Mark an access of the specified entry. Used only in {@code CompactLinkedHashMap} for LRU |
| * ordering. |
| */ |
| void accessEntry(int index) { |
| // no-op by default |
| } |
| |
| @CanIgnoreReturnValue |
| @Override |
| @NullableDecl |
| public V put(@NullableDecl K key, @NullableDecl V value) { |
| long[] entries = this.entries; |
| Object[] keys = this.keys; |
| Object[] values = this.values; |
| |
| int hash = smearedHash(key); |
| int tableIndex = hash & hashTableMask(); |
| int newEntryIndex = this.size; // current size, and pointer to the entry to be appended |
| int next = table[tableIndex]; |
| if (next == UNSET) { |
| table[tableIndex] = newEntryIndex; |
| } else { |
| int last; |
| long entry; |
| do { |
| last = next; |
| entry = entries[next]; |
| if (getHash(entry) == hash && Objects.equal(key, keys[next])) { |
| @SuppressWarnings("unchecked") // known to be a V |
| @NullableDecl |
| V oldValue = (V) values[next]; |
| |
| values[next] = value; |
| accessEntry(next); |
| return oldValue; |
| } |
| next = getNext(entry); |
| } while (next != UNSET); |
| entries[last] = swapNext(entry, newEntryIndex); |
| } |
| if (newEntryIndex == Integer.MAX_VALUE) { |
| throw new IllegalStateException("Cannot contain more than Integer.MAX_VALUE elements!"); |
| } |
| int newSize = newEntryIndex + 1; |
| resizeMeMaybe(newSize); |
| insertEntry(newEntryIndex, key, value, hash); |
| this.size = newSize; |
| if (newEntryIndex >= threshold) { |
| resizeTable(2 * table.length); |
| } |
| modCount++; |
| return null; |
| } |
| |
| /** |
| * Creates a fresh entry with the specified object at the specified position in the entry arrays. |
| */ |
| void insertEntry(int entryIndex, @NullableDecl K key, @NullableDecl V value, int hash) { |
| this.entries[entryIndex] = ((long) hash << 32) | (NEXT_MASK & UNSET); |
| this.keys[entryIndex] = key; |
| this.values[entryIndex] = value; |
| } |
| |
| /** Returns currentSize + 1, after resizing the entries storage if necessary. */ |
| private void resizeMeMaybe(int newSize) { |
| int entriesSize = entries.length; |
| if (newSize > entriesSize) { |
| int newCapacity = entriesSize + Math.max(1, entriesSize >>> 1); |
| if (newCapacity < 0) { |
| newCapacity = Integer.MAX_VALUE; |
| } |
| if (newCapacity != entriesSize) { |
| resizeEntries(newCapacity); |
| } |
| } |
| } |
| |
| /** |
| * Resizes the internal entries array to the specified capacity, which may be greater or less than |
| * the current capacity. |
| */ |
| void resizeEntries(int newCapacity) { |
| this.keys = Arrays.copyOf(keys, newCapacity); |
| this.values = Arrays.copyOf(values, newCapacity); |
| long[] entries = this.entries; |
| int oldCapacity = entries.length; |
| entries = Arrays.copyOf(entries, newCapacity); |
| if (newCapacity > oldCapacity) { |
| Arrays.fill(entries, oldCapacity, newCapacity, UNSET); |
| } |
| this.entries = entries; |
| } |
| |
| private void resizeTable(int newCapacity) { // newCapacity always a power of two |
| int[] oldTable = table; |
| int oldCapacity = oldTable.length; |
| if (oldCapacity >= MAXIMUM_CAPACITY) { |
| threshold = Integer.MAX_VALUE; |
| return; |
| } |
| int newThreshold = 1 + (int) (newCapacity * loadFactor); |
| int[] newTable = newTable(newCapacity); |
| long[] entries = this.entries; |
| |
| int mask = newTable.length - 1; |
| for (int i = 0; i < size; i++) { |
| long oldEntry = entries[i]; |
| int hash = getHash(oldEntry); |
| int tableIndex = hash & mask; |
| int next = newTable[tableIndex]; |
| newTable[tableIndex] = i; |
| entries[i] = ((long) hash << 32) | (NEXT_MASK & next); |
| } |
| |
| this.threshold = newThreshold; |
| this.table = newTable; |
| } |
| |
| private int indexOf(@NullableDecl Object key) { |
| int hash = smearedHash(key); |
| int next = table[hash & hashTableMask()]; |
| while (next != UNSET) { |
| long entry = entries[next]; |
| if (getHash(entry) == hash && Objects.equal(key, keys[next])) { |
| return next; |
| } |
| next = getNext(entry); |
| } |
| return -1; |
| } |
| |
| @Override |
| public boolean containsKey(@NullableDecl Object key) { |
| return indexOf(key) != -1; |
| } |
| |
| @SuppressWarnings("unchecked") // values only contains Vs |
| @Override |
| public V get(@NullableDecl Object key) { |
| int index = indexOf(key); |
| accessEntry(index); |
| return (index == -1) ? null : (V) values[index]; |
| } |
| |
| @CanIgnoreReturnValue |
| @Override |
| @NullableDecl |
| public V remove(@NullableDecl Object key) { |
| return remove(key, smearedHash(key)); |
| } |
| |
| @NullableDecl |
| private V remove(@NullableDecl Object key, int hash) { |
| int tableIndex = hash & hashTableMask(); |
| int next = table[tableIndex]; |
| if (next == UNSET) { // empty bucket |
| return null; |
| } |
| int last = UNSET; |
| do { |
| if (getHash(entries[next]) == hash) { |
| if (Objects.equal(key, keys[next])) { |
| @SuppressWarnings("unchecked") // values only contains Vs |
| @NullableDecl |
| V oldValue = (V) values[next]; |
| |
| if (last == UNSET) { |
| // we need to update the root link from table[] |
| table[tableIndex] = getNext(entries[next]); |
| } else { |
| // we need to update the link from the chain |
| entries[last] = swapNext(entries[last], getNext(entries[next])); |
| } |
| |
| moveLastEntry(next); |
| size--; |
| modCount++; |
| return oldValue; |
| } |
| } |
| last = next; |
| next = getNext(entries[next]); |
| } while (next != UNSET); |
| return null; |
| } |
| |
| @CanIgnoreReturnValue |
| private V removeEntry(int entryIndex) { |
| return remove(keys[entryIndex], getHash(entries[entryIndex])); |
| } |
| |
| /** |
| * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position. |
| */ |
| void moveLastEntry(int dstIndex) { |
| int srcIndex = size() - 1; |
| if (dstIndex < srcIndex) { |
| // move last entry to deleted spot |
| keys[dstIndex] = keys[srcIndex]; |
| values[dstIndex] = values[srcIndex]; |
| keys[srcIndex] = null; |
| values[srcIndex] = null; |
| |
| // move the last entry to the removed spot, just like we moved the element |
| long lastEntry = entries[srcIndex]; |
| entries[dstIndex] = lastEntry; |
| entries[srcIndex] = UNSET; |
| |
| // also need to update whoever's "next" pointer was pointing to the last entry place |
| // reusing "tableIndex" and "next"; these variables were no longer needed |
| int tableIndex = getHash(lastEntry) & hashTableMask(); |
| int lastNext = table[tableIndex]; |
| if (lastNext == srcIndex) { |
| // we need to update the root pointer |
| table[tableIndex] = dstIndex; |
| } else { |
| // we need to update a pointer in an entry |
| int previous; |
| long entry; |
| do { |
| previous = lastNext; |
| lastNext = getNext(entry = entries[lastNext]); |
| } while (lastNext != srcIndex); |
| // here, entries[previous] points to the old entry location; update it |
| entries[previous] = swapNext(entry, dstIndex); |
| } |
| } else { |
| keys[dstIndex] = null; |
| values[dstIndex] = null; |
| entries[dstIndex] = UNSET; |
| } |
| } |
| |
| int firstEntryIndex() { |
| return isEmpty() ? -1 : 0; |
| } |
| |
| int getSuccessor(int entryIndex) { |
| return (entryIndex + 1 < size) ? entryIndex + 1 : -1; |
| } |
| |
| /** |
| * Updates the index an iterator is pointing to after a call to remove: returns the index of the |
| * entry that should be looked at after a removal on indexRemoved, with indexBeforeRemove as the |
| * index that *was* the next entry that would be looked at. |
| */ |
| int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int indexRemoved) { |
| return indexBeforeRemove - 1; |
| } |
| |
| private abstract class Itr<T> implements Iterator<T> { |
| int expectedModCount = modCount; |
| int currentIndex = firstEntryIndex(); |
| int indexToRemove = -1; |
| |
| @Override |
| public boolean hasNext() { |
| return currentIndex >= 0; |
| } |
| |
| abstract T getOutput(int entry); |
| |
| @Override |
| public T next() { |
| checkForConcurrentModification(); |
| if (!hasNext()) { |
| throw new NoSuchElementException(); |
| } |
| indexToRemove = currentIndex; |
| T result = getOutput(currentIndex); |
| currentIndex = getSuccessor(currentIndex); |
| return result; |
| } |
| |
| @Override |
| public void remove() { |
| checkForConcurrentModification(); |
| checkRemove(indexToRemove >= 0); |
| expectedModCount++; |
| removeEntry(indexToRemove); |
| currentIndex = adjustAfterRemove(currentIndex, indexToRemove); |
| indexToRemove = -1; |
| } |
| |
| private void checkForConcurrentModification() { |
| if (modCount != expectedModCount) { |
| throw new ConcurrentModificationException(); |
| } |
| } |
| } |
| |
| @MonotonicNonNullDecl private transient Set<K> keySetView; |
| |
| @Override |
| public Set<K> keySet() { |
| return (keySetView == null) ? keySetView = createKeySet() : keySetView; |
| } |
| |
| Set<K> createKeySet() { |
| return new KeySetView(); |
| } |
| |
| @WeakOuter |
| class KeySetView extends AbstractSet<K> { |
| @Override |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public boolean contains(Object o) { |
| return CompactHashMap.this.containsKey(o); |
| } |
| |
| @Override |
| public boolean remove(@NullableDecl Object o) { |
| int index = indexOf(o); |
| if (index == -1) { |
| return false; |
| } else { |
| removeEntry(index); |
| return true; |
| } |
| } |
| |
| @Override |
| public Iterator<K> iterator() { |
| return keySetIterator(); |
| } |
| |
| @Override |
| public void clear() { |
| CompactHashMap.this.clear(); |
| } |
| } |
| |
| Iterator<K> keySetIterator() { |
| return new Itr<K>() { |
| @SuppressWarnings("unchecked") // keys only contains Ks |
| @Override |
| K getOutput(int entry) { |
| return (K) keys[entry]; |
| } |
| }; |
| } |
| |
| @MonotonicNonNullDecl private transient Set<Entry<K, V>> entrySetView; |
| |
| @Override |
| public Set<Entry<K, V>> entrySet() { |
| return (entrySetView == null) ? entrySetView = createEntrySet() : entrySetView; |
| } |
| |
| Set<Entry<K, V>> createEntrySet() { |
| return new EntrySetView(); |
| } |
| |
| @WeakOuter |
| class EntrySetView extends AbstractSet<Entry<K, V>> { |
| |
| @Override |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public void clear() { |
| CompactHashMap.this.clear(); |
| } |
| |
| @Override |
| public Iterator<Entry<K, V>> iterator() { |
| return entrySetIterator(); |
| } |
| |
| @Override |
| public boolean contains(@NullableDecl Object o) { |
| if (o instanceof Entry) { |
| Entry<?, ?> entry = (Entry<?, ?>) o; |
| int index = indexOf(entry.getKey()); |
| return index != -1 && Objects.equal(values[index], entry.getValue()); |
| } |
| return false; |
| } |
| |
| @Override |
| public boolean remove(@NullableDecl Object o) { |
| if (o instanceof Entry) { |
| Entry<?, ?> entry = (Entry<?, ?>) o; |
| int index = indexOf(entry.getKey()); |
| if (index != -1 && Objects.equal(values[index], entry.getValue())) { |
| removeEntry(index); |
| return true; |
| } |
| } |
| return false; |
| } |
| } |
| |
| Iterator<Entry<K, V>> entrySetIterator() { |
| return new Itr<Entry<K, V>>() { |
| @Override |
| Entry<K, V> getOutput(int entry) { |
| return new MapEntry(entry); |
| } |
| }; |
| } |
| |
| final class MapEntry extends AbstractMapEntry<K, V> { |
| @NullableDecl private final K key; |
| |
| private int lastKnownIndex; |
| |
| @SuppressWarnings("unchecked") // keys only contains Ks |
| MapEntry(int index) { |
| this.key = (K) keys[index]; |
| this.lastKnownIndex = index; |
| } |
| |
| @Override |
| public K getKey() { |
| return key; |
| } |
| |
| private void updateLastKnownIndex() { |
| if (lastKnownIndex == -1 |
| || lastKnownIndex >= size() |
| || !Objects.equal(key, keys[lastKnownIndex])) { |
| lastKnownIndex = indexOf(key); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") // values only contains Vs |
| @Override |
| public V getValue() { |
| updateLastKnownIndex(); |
| return (lastKnownIndex == -1) ? null : (V) values[lastKnownIndex]; |
| } |
| |
| @SuppressWarnings("unchecked") // values only contains Vs |
| @Override |
| public V setValue(V value) { |
| updateLastKnownIndex(); |
| if (lastKnownIndex == -1) { |
| put(key, value); |
| return null; |
| } else { |
| V old = (V) values[lastKnownIndex]; |
| values[lastKnownIndex] = value; |
| return old; |
| } |
| } |
| } |
| |
| @Override |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return size == 0; |
| } |
| |
| @Override |
| public boolean containsValue(@NullableDecl Object value) { |
| for (int i = 0; i < size; i++) { |
| if (Objects.equal(value, values[i])) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| @MonotonicNonNullDecl private transient Collection<V> valuesView; |
| |
| @Override |
| public Collection<V> values() { |
| return (valuesView == null) ? valuesView = createValues() : valuesView; |
| } |
| |
| Collection<V> createValues() { |
| return new ValuesView(); |
| } |
| |
| @WeakOuter |
| class ValuesView extends AbstractCollection<V> { |
| @Override |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public void clear() { |
| CompactHashMap.this.clear(); |
| } |
| |
| @Override |
| public Iterator<V> iterator() { |
| return valuesIterator(); |
| } |
| } |
| |
| Iterator<V> valuesIterator() { |
| return new Itr<V>() { |
| @SuppressWarnings("unchecked") // values only contains Vs |
| @Override |
| V getOutput(int entry) { |
| return (V) values[entry]; |
| } |
| }; |
| } |
| |
| /** |
| * Ensures that this {@code CompactHashMap} has the smallest representation in memory, given its |
| * current size. |
| */ |
| public void trimToSize() { |
| int size = this.size; |
| if (size < entries.length) { |
| resizeEntries(size); |
| } |
| // size / loadFactor gives the table size of the appropriate load factor, |
| // but that may not be a power of two. We floor it to a power of two by |
| // keeping its highest bit. But the smaller table may have a load factor |
| // larger than what we want; then we want to go to the next power of 2 if we can |
| int minimumTableSize = Math.max(1, Integer.highestOneBit((int) (size / loadFactor))); |
| if (minimumTableSize < MAXIMUM_CAPACITY) { |
| double load = (double) size / minimumTableSize; |
| if (load > loadFactor) { |
| minimumTableSize <<= 1; // increase to next power if possible |
| } |
| } |
| |
| if (minimumTableSize < table.length) { |
| resizeTable(minimumTableSize); |
| } |
| } |
| |
| @Override |
| public void clear() { |
| modCount++; |
| Arrays.fill(keys, 0, size, null); |
| Arrays.fill(values, 0, size, null); |
| Arrays.fill(table, UNSET); |
| Arrays.fill(entries, UNSET); |
| this.size = 0; |
| } |
| |
| /** |
| * The serial form currently mimics Android's java.util.HashMap version, e.g. see |
| * http://omapzoom.org/?p=platform/libcore.git;a=blob;f=luni/src/main/java/java/util/HashMap.java |
| */ |
| private void writeObject(ObjectOutputStream stream) throws IOException { |
| stream.defaultWriteObject(); |
| stream.writeInt(size); |
| for (int i = 0; i < size; i++) { |
| stream.writeObject(keys[i]); |
| stream.writeObject(values[i]); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { |
| stream.defaultReadObject(); |
| init(DEFAULT_SIZE, DEFAULT_LOAD_FACTOR); |
| int elementCount = stream.readInt(); |
| for (int i = elementCount; --i >= 0; ) { |
| K key = (K) stream.readObject(); |
| V value = (V) stream.readObject(); |
| put(key, value); |
| } |
| } |
| } |