MultiValueHashMap.java
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package org.hsqldb.lib;
import org.hsqldb.map.BaseHashMap;
/**
* A Map of Object keys to Object values which stores multiple values per
* key. The getValuesIterator(K key) method returns an iterator covering the
* values associated with the given key. The get(K key) method returns the first
* value (if any) associated with the key.<p>
*
* This class does not store null keys.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.7.3
* @since 1.9.0
*/
public class MultiValueHashMap<K, V> extends BaseHashMap implements Map<K, V> {
private Set<K> keySet;
private Collection<V> values;
private Set<Entry<K, V>> entries;
public MultiValueHashMap() {
this(8);
}
public MultiValueHashMap(
int initialCapacity)
throws IllegalArgumentException {
super(
initialCapacity,
BaseHashMap.objectKeyOrValue,
BaseHashMap.objectKeyOrValue,
false);
this.isMultiValue = true;
}
public MultiValueHashMap(
int initialCapacity,
ObjectComparator<K> comparator)
throws IllegalArgumentException {
this(initialCapacity);
this.comparator = comparator;
}
public boolean containsKey(Object key) {
if (key == null) {
throw new NullPointerException();
}
return super.containsObjectKey(key);
}
public boolean containsValue(Object value) {
return super.containsValue(value);
}
/**
* Returns one of the values associated with the given key.
*
* @param key the key
* @return any value associated with the key, or null if none
*/
public V get(K key) {
if (key == null) {
throw new NullPointerException();
}
int hash = comparator.hashCode(key);
int lookup = getLookup(key, hash);
if (lookup != -1) {
return (V) objectValueTable[lookup];
}
return null;
}
/**
* Returns an iterator on all values associated with the key.
*
* @param key the key
* @return iterator on value associated with the key
*/
public Iterator<V> getValuesIterator(Object key) {
if (key == null) {
throw new NullPointerException();
}
return super.getMultiValuesIterator(key);
}
public V put(K key, V value) {
if (key == null) {
throw new NullPointerException();
}
boolean added = super.addMultiVal(0, 0, key, value);
return added
? null
: value;
}
/**
* Removes all values associated with the key.
*
* @param key the key
* @return any value associated with the key, or null if none
*/
public V remove(Object key) {
if (key == null) {
throw new NullPointerException();
}
return (V) super.removeMultiVal(0, 0, key, null, false);
}
/**
* Removes the spacific value associated with the key.
*
* @param key the key
* @param value the value
* @return the value associated with the key, or null if none
*/
public boolean remove(K key, V value) {
if (key == null) {
throw new NullPointerException();
}
Object result = super.removeMultiVal(0, 0, key, value, true);
return result != null;
}
/**
* Counts the values associated with the key.
*
* @param key the key
* @return the count
*/
public int valueCount(K key) {
if (key == null) {
throw new NullPointerException();
}
int hash = comparator.hashCode(key);
return super.multiValueElementCount(key);
}
public void putAll(Map<K, V> m) {
Iterator<K> it = m.keySet().iterator();
while (it.hasNext()) {
K key = it.next();
if (key == null) {
continue;
}
put(key, m.get(key));
}
}
public void putAll(MultiValueHashMap<K, V> m) {
Iterator<K> it = m.keySet().iterator();
while (it.hasNext()) {
K key = it.next();
Iterator<V> valueSet = m.getValuesIterator(key);
while (valueSet.hasNext()) {
V value = valueSet.next();
put(key, value);
}
}
}
public <T> T[] keysToArray(T[] array) {
return toArray(array, true);
}
public <T> T[] valuesToArray(T[] array) {
return toArray(array, false);
}
public Set<K> keySet() {
if (keySet == null) {
keySet = new KeySet();
}
return keySet;
}
public Collection<V> values() {
if (values == null) {
values = new Values();
}
return values;
}
public Set<Entry<K, V>> entrySet() {
if (entries == null) {
entries = new EntrySet();
}
return entries;
}
private class EntrySet extends AbstractReadOnlyCollection<Entry<K, V>>
implements Set<Map.Entry<K, V>> {
public Iterator<Entry<K, V>> iterator() {
return MultiValueHashMap.this.new EntrySetIterator<K, V>();
}
public int size() {
return MultiValueHashMap.this.size();
}
public boolean isEmpty() {
return size() == 0;
}
}
private class EntrySetIterator<K, V> extends BaseHashIterator {
EntrySetIterator() {
super(true);
}
public Entry<K, V> next() {
K key = (K) super.next();
V value = (V) objectValueTable[lookup];
return new MapEntry<K, V>(key, value);
}
}
private class KeySet extends AbstractReadOnlyCollection<K>
implements Set<K> {
public Iterator<K> iterator() {
return MultiValueHashMap.this.new MultiValueKeyIterator();
}
public int size() {
return MultiValueHashMap.this.multiValueKeyCount();
}
public boolean isEmpty() {
return size() == 0;
}
}
private class Values extends AbstractReadOnlyCollection<V> {
public Iterator<V> iterator() {
return MultiValueHashMap.this.new BaseHashIterator(false);
}
public int size() {
return MultiValueHashMap.this.size();
}
public boolean isEmpty() {
return size() == 0;
}
}
}