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.Collection;
024import java.util.Map;
025import java.util.Set;
026import java.util.SortedMap;
027
028import org.apache.commons.collections4.BoundedMap;
029import org.apache.commons.collections4.CollectionUtils;
030import org.apache.commons.collections4.collection.UnmodifiableCollection;
031import org.apache.commons.collections4.set.UnmodifiableSet;
032
033/**
034 * Decorates another <code>SortedMap</code> to fix the size blocking add/remove.
035 * <p>
036 * Any action that would change the size of the map is disallowed.
037 * The put method is allowed to change the value associated with an existing
038 * key however.
039 * <p>
040 * If trying to remove or clear the map, an UnsupportedOperationException is
041 * thrown. If trying to put a new mapping into the map, an
042 * IllegalArgumentException is thrown. This is because the put method can
043 * succeed if the mapping's key already exists in the map, so the put method
044 * is not always unsupported.
045 * <p>
046 * <strong>Note that FixedSizeSortedMap is not synchronized and is not thread-safe.</strong>
047 * If you wish to use this map from multiple threads concurrently, you must use
048 * appropriate synchronization. The simplest approach is to wrap this map
049 * using {@link java.util.Collections#synchronizedSortedMap}. This class may throw
050 * exceptions when accessed by concurrent threads without synchronization.
051 * <p>
052 * This class is Serializable from Commons Collections 3.1.
053 *
054 * @param <K> the type of the keys in this map
055 * @param <V> the type of the values in this map
056 * @since 3.0
057 */
058public class FixedSizeSortedMap<K, V>
059        extends AbstractSortedMapDecorator<K, V>
060        implements BoundedMap<K, V>, Serializable {
061
062    /** Serialization version */
063    private static final long serialVersionUID = 3126019624511683653L;
064
065    /**
066     * Factory method to create a fixed size sorted map.
067     *
068     * @param <K>  the key type
069     * @param <V>  the value type
070     * @param map  the map to decorate, must not be null
071     * @return a new fixed size sorted map
072     * @throws NullPointerException if map is null
073     * @since 4.0
074     */
075    public static <K, V> FixedSizeSortedMap<K, V> fixedSizeSortedMap(final SortedMap<K, V> map) {
076        return new FixedSizeSortedMap<>(map);
077    }
078
079    //-----------------------------------------------------------------------
080    /**
081     * Constructor that wraps (not copies).
082     *
083     * @param map  the map to decorate, must not be null
084     * @throws NullPointerException if map is null
085     */
086    protected FixedSizeSortedMap(final SortedMap<K, V> map) {
087        super(map);
088    }
089
090    /**
091     * Gets the map being decorated.
092     *
093     * @return the decorated map
094     */
095    protected SortedMap<K, V> getSortedMap() {
096        return (SortedMap<K, V>) map;
097    }
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        out.writeObject(map);
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    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
119    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
120        in.defaultReadObject();
121        map = (Map<K, V>) in.readObject(); // (1)
122    }
123
124    //-----------------------------------------------------------------------
125    @Override
126    public V put(final K key, final V value) {
127        if (map.containsKey(key) == false) {
128            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
129        }
130        return map.put(key, value);
131    }
132
133    @Override
134    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
135        if (CollectionUtils.isSubCollection(mapToCopy.keySet(), keySet())) {
136            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
137        }
138        map.putAll(mapToCopy);
139    }
140
141    @Override
142    public void clear() {
143        throw new UnsupportedOperationException("Map is fixed size");
144    }
145
146    @Override
147    public V remove(final Object key) {
148        throw new UnsupportedOperationException("Map is fixed size");
149    }
150
151    @Override
152    public Set<Map.Entry<K, V>> entrySet() {
153        return UnmodifiableSet.unmodifiableSet(map.entrySet());
154    }
155
156    @Override
157    public Set<K> keySet() {
158        return UnmodifiableSet.unmodifiableSet(map.keySet());
159    }
160
161    @Override
162    public Collection<V> values() {
163        return UnmodifiableCollection.unmodifiableCollection(map.values());
164    }
165
166    //-----------------------------------------------------------------------
167    @Override
168    public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
169        return new FixedSizeSortedMap<>(getSortedMap().subMap(fromKey, toKey));
170    }
171
172    @Override
173    public SortedMap<K, V> headMap(final K toKey) {
174        return new FixedSizeSortedMap<>(getSortedMap().headMap(toKey));
175    }
176
177    @Override
178    public SortedMap<K, V> tailMap(final K fromKey) {
179        return new FixedSizeSortedMap<>(getSortedMap().tailMap(fromKey));
180    }
181
182    @Override
183    public boolean isFull() {
184        return true;
185    }
186
187    @Override
188    public int maxSize() {
189        return size();
190    }
191
192}