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}