1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections.map;
18
19 import java.io.IOException;
20 import java.io.ObjectInputStream;
21 import java.io.ObjectOutputStream;
22 import java.io.Serializable;
23 import java.util.Map;
24
25 /**
26 * A <code>Map</code> implementation that is a general purpose alternative
27 * to <code>HashMap</code>.
28 * <p>
29 * This implementation improves on the JDK1.4 HashMap by adding the
30 * {@link org.apache.commons.collections.MapIterator MapIterator}
31 * functionality and many methods for subclassing.
32 * <p>
33 * <strong>Note that HashedMap is not synchronized and is not thread-safe.</strong>
34 * If you wish to use this map from multiple threads concurrently, you must use
35 * appropriate synchronization. The simplest approach is to wrap this map
36 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
37 * exceptions when accessed by concurrent threads without synchronization.
38 *
39 * @since 3.0
40 * @version $Id: HashedMap.java 1429905 2013-01-07 17:15:14Z ggregory $
41 */
42 public class HashedMap<K, V>
43 extends AbstractHashedMap<K, V> implements Serializable, Cloneable {
44
45 /** Serialisation version */
46 private static final long serialVersionUID = -1788199231038721040L;
47
48 /**
49 * Constructs a new empty map with default size and load factor.
50 */
51 public HashedMap() {
52 super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
53 }
54
55 /**
56 * Constructs a new, empty map with the specified initial capacity.
57 *
58 * @param initialCapacity the initial capacity
59 * @throws IllegalArgumentException if the initial capacity is negative
60 */
61 public HashedMap(final int initialCapacity) {
62 super(initialCapacity);
63 }
64
65 /**
66 * Constructs a new, empty map with the specified initial capacity and
67 * load factor.
68 *
69 * @param initialCapacity the initial capacity
70 * @param loadFactor the load factor
71 * @throws IllegalArgumentException if the initial capacity is negative
72 * @throws IllegalArgumentException if the load factor is less than zero
73 */
74 public HashedMap(final int initialCapacity, final float loadFactor) {
75 super(initialCapacity, loadFactor);
76 }
77
78 /**
79 * Constructor copying elements from another map.
80 *
81 * @param map the map to copy
82 * @throws NullPointerException if the map is null
83 */
84 public HashedMap(final Map<K, V> map) {
85 super(map);
86 }
87
88 //-----------------------------------------------------------------------
89 /**
90 * Clones the map without cloning the keys or values.
91 *
92 * @return a shallow clone
93 */
94 @Override
95 public HashedMap<K, V> clone() {
96 return (HashedMap<K, V>) super.clone();
97 }
98
99 /**
100 * Write the map out using a custom routine.
101 */
102 private void writeObject(final ObjectOutputStream out) throws IOException {
103 out.defaultWriteObject();
104 doWriteObject(out);
105 }
106
107 /**
108 * Read the map in using a custom routine.
109 */
110 private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
111 in.defaultReadObject();
112 doReadObject(in);
113 }
114
115 }