    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 * <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    /**
    085     * Constructor that wraps (not copies).
    086     *
    087     * @param map  the map to decorate, must not be null
    088     * @throws NullPointerException if map is null
    089     */
    090    protected FixedSizeSortedMap(final SortedMap<K, V> map) {
    091        super(map);
    092    }
    093
    094    /**
    095     * Gets the map being decorated.
    096     *
    097     * @return the decorated map
    098     */
    099    protected SortedMap<K, V> getSortedMap() {
    100        return (SortedMap<K, V>) map;
    101    }
    102
    103    //-----------------------------------------------------------------------
    104    /**
    105     * Write the map out using a custom routine.
    106     *
    107     * @param out  the output stream
    108     * @throws IOException if an error occurs while writing to the stream
    109     */
    110    private void writeObject(final ObjectOutputStream out) throws IOException {
    111        out.defaultWriteObject();
    112        out.writeObject(map);
    113    }
    114
    115    /**
    116     * Read the map in using a custom routine.
    117     *
    118     * @param in the input stream
    119     * @throws IOException if an error occurs while reading from the stream
    120     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    121     */
    122    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    123    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    124        in.defaultReadObject();
    125        map = (Map<K, V>) in.readObject(); // (1)
    126    }
    127
    128    //-----------------------------------------------------------------------
    129    @Override
    130    public V put(final K key, final V value) {
    131        if (map.containsKey(key) == false) {
    132            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
    133        }
    134        return map.put(key, value);
    135    }
    136
    137    @Override
    138    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
    139        if (CollectionUtils.isSubCollection(mapToCopy.keySet(), keySet())) {
    140            throw new IllegalArgumentException("Cannot put new key/value pair - Map is fixed size");
    141        }
    142        map.putAll(mapToCopy);
    143    }
    144
    145    @Override
    146    public void clear() {
    147        throw new UnsupportedOperationException("Map is fixed size");
    148    }
    149
    150    @Override
    151    public V remove(final Object key) {
    152        throw new UnsupportedOperationException("Map is fixed size");
    153    }
    154
    155    @Override
    156    public Set<Map.Entry<K, V>> entrySet() {
    157        return UnmodifiableSet.unmodifiableSet(map.entrySet());
    158    }
    159
    160    @Override
    161    public Set<K> keySet() {
    162        return UnmodifiableSet.unmodifiableSet(map.keySet());
    163    }
    164
    165    @Override
    166    public Collection<V> values() {
    167        return UnmodifiableCollection.unmodifiableCollection(map.values());
    168    }
    169
    170    //-----------------------------------------------------------------------
    171    @Override
    172    public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
    173        return new FixedSizeSortedMap<>(getSortedMap().subMap(fromKey, toKey));
    174    }
    175
    176    @Override
    177    public SortedMap<K, V> headMap(final K toKey) {
    178        return new FixedSizeSortedMap<>(getSortedMap().headMap(toKey));
    179    }
    180
    181    @Override
    182    public SortedMap<K, V> tailMap(final K fromKey) {
    183        return new FixedSizeSortedMap<>(getSortedMap().tailMap(fromKey));
    184    }
    185
    186    @Override
    187    public boolean isFull() {
    188        return true;
    189    }
    190
    191    @Override
    192    public int maxSize() {
    193        return size();
    194    }
    195
    196}