/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.collections15.bidimap;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.collections15.BidiMap;
/**
* Implementation of <code>BidiMap</code> that uses two <code>HashMap</code>
* instances.
* <p>
* Two <code>HashMap</code> instances are used in this class. This provides fast
* lookups at the expense of storing two sets of map entries. Commons
* Collections would welcome the addition of a direct hash-based implementation
* of the <code>BidiMap</code> interface.
* <p>
* NOTE: From Commons Collections 3.1, all subclasses will use
* <code>HashMap</code> and the flawed <code>createMap</code> method is ignored.
*
* @since Commons Collections 3.0
* @version $Id$
*
* @author Matthew Hawthorne
* @author Stephen Colebourne
*/
public class DualHashBidiMap<K, V> extends AbstractDualBidiMap<K, V> {
/**
* Creates an empty <code>HashBidiMap</code>.
*/
public DualHashBidiMap() {
super(new HashMap<K, V>(), new HashMap<V, K>());
}
/**
* Constructs a <code>HashBidiMap</code> and copies the mappings from
* specified <code>Map</code>.
*
* @param map
* the map whose mappings are to be placed in this map
*/
public DualHashBidiMap(Map<K, V> map) {
super(new HashMap<K, V>(), new HashMap<V, K>());
putAll(map);
}
/**
* Constructs a <code>HashBidiMap</code> that decorates the specified maps.
*
* @param normalMap
* the normal direction map
* @param reverseMap
* the reverse direction map
* @param inverseBidiMap
* the inverse BidiMap
*/
protected DualHashBidiMap(Map<K, V> normalMap, Map<V, K> reverseMap,
BidiMap<V, K> inverseBidiMap) {
super(normalMap, reverseMap, inverseBidiMap);
}
/**
* Creates a new instance of this object.
*
* @param normalMap
* the normal direction map
* @param reverseMap
* the reverse direction map
* @param inverseBidiMap
* the inverse BidiMap
* @return new bidi map
*/
@Override
protected BidiMap<V, K> createBidiMap(Map<V, K> normalMap,
Map<K, V> reverseMap, BidiMap<K, V> inverseBidiMap) {
return new DualHashBidiMap<V, K>(normalMap, reverseMap, inverseBidiMap);
}
}