    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} 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 * <p>
    041 * If trying to remove or clear the map, an UnsupportedOperationException is
    042 * thrown. If trying to put a new mapping into the map, an
    043 * IllegalArgumentException is thrown. This is because the put method can
    044 * succeed if the mapping's key already exists in the map, so the put method
    045 * is not always unsupported.
    046 * </p>
    047 * <p>
    048 * <strong>Note that FixedSizeSortedMap is not synchronized and is not thread-safe.</strong>
    049 * If you wish to use this map from multiple threads concurrently, you must use
    050 * appropriate synchronization. The simplest approach is to wrap this map
    051 * using {@link java.util.Collections#synchronizedSortedMap}. This class may throw
    052 * exceptions when accessed by concurrent threads without synchronization.
    053 * </p>
    054 * <p>
    055 * This class is Serializable from Commons Collections 3.1.
    056 * </p>
    057 *
    058 * @param <K> the type of the keys in this map
    059 * @param <V> the type of the values in this map
    060 * @since 3.0
    061 */
    062public class FixedSizeSortedMap<K, V>
    063        extends AbstractSortedMapDecorator<K, V>
    064        implements BoundedMap<K, V>, Serializable {
    065
    066    /** Serialization version */
    067    private static final long serialVersionUID = 3126019624511683653L;
    068
    069    /**
    070     * Factory method to create a fixed size sorted map.
    071     *
    072     * @param <K>  the key type
    073     * @param <V>  the value type
    074     * @param map  the map to decorate, must not be null
    075     * @return a new fixed size sorted map
    076     * @throws NullPointerException if map is null
    077     * @since 4.0
    078     */
    079    public static <K, V> FixedSizeSortedMap<K, V> fixedSizeSortedMap(final SortedMap<K, V> map) {
    080        return new FixedSizeSortedMap<>(map);
    081    }
    082
    083    /**
    084     * Constructor that wraps (not copies).
    085     *
    086     * @param map  the map to decorate, must not be null
    087     * @throws NullPointerException if map is null
    088     */
    089    protected FixedSizeSortedMap(final SortedMap<K, V> map) {
    090        super(map);
    091    }
    092
    093    @Override
    094    public void clear() {
    095        throw new UnsupportedOperationException("Map is fixed size");
    096    }
    097
    098    @Override
    099    public Set<Map.Entry<K, V>> entrySet() {
    100        return UnmodifiableSet.unmodifiableSet(map.entrySet());
    101    }
    102
    103    /**
    104     * Gets the map being decorated.
    105     *
    106     * @return the decorated map
    107     */
    108    protected SortedMap<K, V> getSortedMap() {
    109        return (SortedMap<K, V>) map;
    110    }
    111
    112    @Override
    113    public SortedMap<K, V> headMap(final K toKey) {
    114        return new FixedSizeSortedMap<>(getSortedMap().headMap(toKey));
    115    }
    116
    117    @Override
    118    public boolean isFull() {
    119        return true;
    120    }
    121
    122    @Override
    123    public Set<K> keySet() {
    124        return UnmodifiableSet.unmodifiableSet(map.keySet());
    125    }
    126
    127    @Override
    128    public int maxSize() {
    129        return size();
    130    }
    131
    132    @Override
    133    public V put(final K key, final V value) {
    134        if (!map.containsKey(key)) {
    135            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
    136        }
    137        return map.put(key, value);
    138    }
    139
    140    @Override
    141    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
    142        if (CollectionUtils.isSubCollection(mapToCopy.keySet(), keySet())) {
    143            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
    144        }
    145        map.putAll(mapToCopy);
    146    }
    147
    148    /**
    149     * Read the map in using a custom routine.
    150     *
    151     * @param in the input stream
    152     * @throws IOException if an error occurs while reading from the stream
    153     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    154     */
    155    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    156    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    157        in.defaultReadObject();
    158        map = (Map<K, V>) in.readObject(); // (1)
    159    }
    160
    161    @Override
    162    public V remove(final Object key) {
    163        throw new UnsupportedOperationException("Map is fixed size");
    164    }
    165
    166    @Override
    167    public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
    168        return new FixedSizeSortedMap<>(getSortedMap().subMap(fromKey, toKey));
    169    }
    170
    171    @Override
    172    public SortedMap<K, V> tailMap(final K fromKey) {
    173        return new FixedSizeSortedMap<>(getSortedMap().tailMap(fromKey));
    174    }
    175
    176    @Override
    177    public Collection<V> values() {
    178        return UnmodifiableCollection.unmodifiableCollection(map.values());
    179    }
    180
    181    /**
    182     * Write the map out using a custom routine.
    183     *
    184     * @param out  the output stream
    185     * @throws IOException if an error occurs while writing to the stream
    186     */
    187    private void writeObject(final ObjectOutputStream out) throws IOException {
    188        out.defaultWriteObject();
    189        out.writeObject(map);
    190    }
    191
    192}