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package test;
import java.util.*;
/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2006</p>
* <p>Company: </p>
* @author Fabrice Bouyé (fabriceb@spc.int)
* @version 1.0
*/
public class BidiMap<K, V> implements Map<K, V> {
/** Sub-container type for this map.
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2006</p>
* <p>Company: </p>
* @author Fabrice Bouyé (fabriceb@spc.int)
* @version 1.0
*/
public enum Flavor {
HASH_MAP, HASH_TABLE, TREE_MAP;
}
/** Main delegated map.
* Has a 1 -> 1 relationship between key and value.
*/
private Map<K, V> delegated;
/** The reverse delegated map.
* Has a 1 -> * relationship between the value and the key.
*/
private Map<V, List<K>> reverseDelegated;
/** Creates a new instance with hashmaps.
*/
public BidiMap() {
this(Flavor.HASH_MAP);
}
/** Creates a new instance with given flavor containers.
* @param flavor The container type.
* @see #Flavor
*/
public BidiMap(Flavor flavor) {
switch (flavor) {
case HASH_TABLE: {
delegated = new Hashtable<K, V>();
reverseDelegated = new Hashtable<V, List<K>>();
}
break;
//
case TREE_MAP: {
delegated = new TreeMap<K, V>();
reverseDelegated = new TreeMap<V, List<K>>();
}
break;
//
case HASH_MAP:
default: {
delegated = new HashMap<K, V>();
reverseDelegated = new HashMap<V, List<K>>();
}
}
}
/** {@inheritDoc}
*/
public void clear() {
delegated.clear();
reverseDelegated.clear();
}
/** {@inheritDoc}
*/
public boolean containsKey(Object key) {
return delegated.containsKey(key);
}
/** {@inheritDoc}
*/
public boolean containsValue(Object value) {
// Should be faster this way.
return reverseDelegated.containsKey(value);
}
/** {@inheritDoc}
*/
public Set<Map.Entry<K, V>> entrySet() {
return delegated.entrySet();
}
/** {@inheritDoc}
*/
public V get(Object key) {
return delegated.get(key);
}
/** {@inheritDoc}
*/
public boolean isEmpty() {
return delegated.isEmpty();
}
/** {@inheritDoc}
*/
public Set<K> keySet() {
return delegated.keySet();
}
/** {@inheritDoc}
*/
public V put(K key, V value) {
V oldValue = delegated.put(key, value);
if (oldValue != null) {
List<K> keyList = reverseDelegated.get(oldValue);
if (keyList != null) {
keyList.remove(key);
}
}
if (value != null) {
List<K> keyList = reverseDelegated.get(value);
if (keyList == null) {
keyList = new LinkedList<K>();
reverseDelegated.put(value, keyList);
}
if (!keyList.contains(key)) {
keyList.add(key);
}
}
return oldValue;
}
/** {@inheritDoc}
*/
public void putAll(Map<? extends K, ? extends V> t) {
for (K key : t.keySet()) {
V value = t.get(key);
put(key, value);
}
}
/** {@inheritDoc}
*/
public V remove(Object key) {
V value = delegated.remove(key);
if (value != null) {
reverseDelegated.remove(value);
}
return value;
}
/** {@inheritDoc}
*/
public int size() {
return delegated.size();
}
/** {@inheritDoc}
*/
public Collection<V> values() {
return delegated.values();
}
/** Gets all keys for a given value.
* @param value The queried value.
* @return A non-modifiable list of keys, maybe <code>null</code>.
*/
public List<K> keysForValue(V value) {
List<K> result = reverseDelegated.get(value);
if (result != null) {
result = Collections.unmodifiableList(result);
}
return result;
}
} |
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