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 *  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.map;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Map;

A Map implementation that is a general purpose alternative
to HashMap.
 This implementation improves on the JDK1.4 HashMap by adding the MapIterator functionality and many methods for subclassing. 

Note that HashedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map<Object,Object>). This class may throw exceptions when accessed by concurrent threads without synchronization. 
Author:
Stephen Colebourne
Since:
Commons Collections 3.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $/**
 * A <code>Map</code> implementation that is a general purpose alternative
 * to <code>HashMap</code>.
 * <p>
 * This implementation improves on the JDK1.4 HashMap by adding the 
 * {@link org.apache.commons.collections.MapIterator MapIterator}
 * functionality and many methods for subclassing.
 * <p>
 * <strong>Note that HashedMap is not synchronized and is not thread-safe.</strong>
 * If you wish to use this map from multiple threads concurrently, you must use
 * appropriate synchronization. The simplest approach is to wrap this map
 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw 
 * exceptions when accessed by concurrent threads without synchronization.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
 *
 * @author Stephen Colebourne
 */
public class HashedMap
        extends AbstractHashedMap implements Serializable, Cloneable {

    
Serialisation version /** Serialisation version */
    private static final long serialVersionUID = -1788199231038721040L;
    
    
Constructs a new empty map with default size and load factor.
/**
     * Constructs a new empty map with default size and load factor.
     */
    public HashedMap() {
        super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
    }

    
Constructs a new, empty map with the specified initial capacity. 
Params:
initialCapacity –  the initial capacity
Throws:
IllegalArgumentException – if the initial capacity is less than one/**
     * Constructs a new, empty map with the specified initial capacity. 
     *
     * @param initialCapacity  the initial capacity
     * @throws IllegalArgumentException if the initial capacity is less than one
     */
    public HashedMap(int initialCapacity) {
        super(initialCapacity);
    }

    
Constructs a new, empty map with the specified initial capacity and
load factor. 
Params:
initialCapacity –  the initial capacity
loadFactor –  the load factor
Throws:
IllegalArgumentException – if the initial capacity is less than one
IllegalArgumentException – if the load factor is less than zero/**
     * Constructs a new, empty map with the specified initial capacity and
     * load factor. 
     *
     * @param initialCapacity  the initial capacity
     * @param loadFactor  the load factor
     * @throws IllegalArgumentException if the initial capacity is less than one
     * @throws IllegalArgumentException if the load factor is less than zero
     */
    public HashedMap(int initialCapacity, float loadFactor) {
        super(initialCapacity, loadFactor);
    }

    
Constructor copying elements from another map.
Params:
map –  the map to copy
Throws:
NullPointerException – if the map is null/**
     * Constructor copying elements from another map.
     *
     * @param map  the map to copy
     * @throws NullPointerException if the map is null
     */
    public HashedMap(Map map) {
        super(map);
    }

    //-----------------------------------------------------------------------
    
Clones the map without cloning the keys or values.
Returns:
a shallow clone/**
     * Clones the map without cloning the keys or values.
     *
     * @return a shallow clone
     */
    public Object clone() {
        return super.clone();
    }
    
    
Write the map out using a custom routine.
/**
     * Write the map out using a custom routine.
     */
    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        doWriteObject(out);
    }

    
Read the map in using a custom routine.
/**
     * Read the map in using a custom routine.
     */
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        doReadObject(in);
    }
    
}