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/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003-2004 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache"
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */
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.
 * 
 * @since Commons Collections 3.0
 * @version $Id: DualHashBidiMap.java,v 1.5 2004/01/14 21:43:16 scolebourne Exp $
 * 
 * @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();
    }

    /** 
     * 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();
        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 the map used by the subclass to store data.
     * 
     * @return the map to be used for internal storage
     */
    protected Map createMap() {
        return new HashMap();
    }

    /**
     * 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();
        Map map = (Map) in.readObject();
        putAll(map);
    }

}