org.apache.commons.collections.bidimap.DualHashBidiMap Maven / Gradle / Ivy
/*
* 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.collections.bidimap;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.collections.BidiMap;
/**
* Implementation of BidiMap that uses two HashMap instances.
*
* Two HashMap 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 BidiMap interface.
*
* NOTE: From Commons Collections 3.1, all subclasses will use HashMap
* and the flawed createMap method is ignored.
*
* @since Commons Collections 3.0
* @version $Id: DualHashBidiMap.java 646777 2008-04-10 12:33:15Z niallp $
*
* @author Matthew Hawthorne
* @author Stephen Colebourne
*/
public class DualHashBidiMap
extends AbstractDualBidiMap implements Serializable {
/** Ensure serialization compatibility */
private static final long serialVersionUID = 721969328361808L;
/**
* Creates an empty HashBidiMap.
*/
public DualHashBidiMap() {
super(new HashMap(), new HashMap());
}
/**
* Constructs a HashBidiMap and copies the mappings from
* specified Map.
*
* @param map the map whose mappings are to be placed in this map
*/
public DualHashBidiMap(Map map) {
super(new HashMap(), new HashMap());
putAll(map);
}
/**
* Constructs a HashBidiMap 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 normalMap, Map reverseMap, BidiMap 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
*/
protected BidiMap createBidiMap(Map normalMap, Map reverseMap, BidiMap inverseBidiMap) {
return new DualHashBidiMap(normalMap, reverseMap, inverseBidiMap);
}
// Serialization
//-----------------------------------------------------------------------
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(maps[0]);
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
maps[0] = new HashMap();
maps[1] = new HashMap();
Map map = (Map) in.readObject();
putAll(map);
}
}