    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.map;
    018
    019import java.io.IOException;
    020import java.io.ObjectInputStream;
    021import java.io.ObjectOutputStream;
    022import java.io.Serializable;
    023import java.util.Map;
    024
    025/**
    026 * A <code>Map</code> implementation that is a general purpose alternative
    027 * to <code>HashMap</code>.
    028 * <p>
    029 * This implementation improves on the JDK1.4 HashMap by adding the
    030 * {@link org.apache.commons.collections4.MapIterator MapIterator}
    031 * functionality and many methods for subclassing.
    032 * <p>
    033 * <strong>Note that HashedMap is not synchronized and is not thread-safe.</strong>
    034 * If you wish to use this map from multiple threads concurrently, you must use
    035 * appropriate synchronization. The simplest approach is to wrap this map
    036 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
    037 * exceptions when accessed by concurrent threads without synchronization.
    038 *
    039 * @param <K> the type of the keys in this map
    040 * @param <V> the type of the values in this map
    041 * @since 3.0
    042 */
    043public class HashedMap<K, V>
    044        extends AbstractHashedMap<K, V> implements Serializable, Cloneable {
    045
    046    /** Serialisation version */
    047    private static final long serialVersionUID = -1788199231038721040L;
    048
    049    /**
    050     * Constructs a new empty map with default size and load factor.
    051     */
    052    public HashedMap() {
    053        super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
    054    }
    055
    056    /**
    057     * Constructs a new, empty map with the specified initial capacity.
    058     *
    059     * @param initialCapacity  the initial capacity
    060     * @throws IllegalArgumentException if the initial capacity is negative
    061     */
    062    public HashedMap(final int initialCapacity) {
    063        super(initialCapacity);
    064    }
    065
    066    /**
    067     * Constructs a new, empty map with the specified initial capacity and
    068     * load factor.
    069     *
    070     * @param initialCapacity  the initial capacity
    071     * @param loadFactor  the load factor
    072     * @throws IllegalArgumentException if the initial capacity is negative
    073     * @throws IllegalArgumentException if the load factor is less than zero
    074     */
    075    public HashedMap(final int initialCapacity, final float loadFactor) {
    076        super(initialCapacity, loadFactor);
    077    }
    078
    079    /**
    080     * Constructor copying elements from another map.
    081     *
    082     * @param map  the map to copy
    083     * @throws NullPointerException if the map is null
    084     */
    085    public HashedMap(final Map<? extends K, ? extends V> map) {
    086        super(map);
    087    }
    088
    089    //-----------------------------------------------------------------------
    090    /**
    091     * Clones the map without cloning the keys or values.
    092     *
    093     * @return a shallow clone
    094     */
    095    @Override
    096    public HashedMap<K, V> clone() {
    097        return (HashedMap<K, V>) super.clone();
    098    }
    099
    100    /**
    101     * Write the map out using a custom routine.
    102     *
    103     * @param out  the output stream
    104     * @throws IOException if an error occurs while writing to the stream
    105     */
    106    private void writeObject(final ObjectOutputStream out) throws IOException {
    107        out.defaultWriteObject();
    108        doWriteObject(out);
    109    }
    110
    111    /**
    112     * Read the map in using a custom routine.
    113     *
    114     * @param in the input stream
    115     * @throws IOException if an error occurs while reading from the stream
    116     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    117     */
    118    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    119        in.defaultReadObject();
    120        doReadObject(in);
    121    }
    122
    123}