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;
026
027import org.apache.commons.collections4.IterableMap;
028import org.apache.commons.collections4.MapIterator;
029import org.apache.commons.collections4.Unmodifiable;
030import org.apache.commons.collections4.collection.UnmodifiableCollection;
031import org.apache.commons.collections4.iterators.EntrySetMapIterator;
032import org.apache.commons.collections4.iterators.UnmodifiableMapIterator;
033import org.apache.commons.collections4.set.UnmodifiableSet;
034
035/**
036 * Decorates another <code>Map</code> to ensure it can't be altered.
037 * <p>
038 * This class is Serializable from Commons Collections 3.1.
039 * <p>
040 * Attempts to modify it will result in an UnsupportedOperationException.
041 *
042 * @param <K> the type of the keys in this map
043 * @param <V> the type of the values in this map
044 * @since 3.0
045 */
046public final class UnmodifiableMap<K, V>
047        extends AbstractMapDecorator<K, V>
048        implements Unmodifiable, Serializable {
049
050    /** Serialization version */
051    private static final long serialVersionUID = 2737023427269031941L;
052
053    /**
054     * Factory method to create an unmodifiable map.
055     *
056     * @param <K>  the key type
057     * @param <V>  the value type
058     * @param map  the map to decorate, must not be null
059     * @return a new unmodifiable map
060     * @throws NullPointerException if map is null
061     * @since 4.0
062     */
063    public static <K, V> Map<K, V> unmodifiableMap(final Map<? extends K, ? extends V> map) {
064        if (map instanceof Unmodifiable) {
065            @SuppressWarnings("unchecked") // safe to upcast
066            final Map<K, V> tmpMap = (Map<K, V>) map;
067            return tmpMap;
068        }
069        return new UnmodifiableMap<>(map);
070    }
071
072    //-----------------------------------------------------------------------
073    /**
074     * Constructor that wraps (not copies).
075     *
076     * @param map  the map to decorate, must not be null
077     * @throws NullPointerException if map is null
078     */
079    @SuppressWarnings("unchecked") // safe to upcast
080    private UnmodifiableMap(final Map<? extends K, ? extends V> map) {
081        super((Map<K, V>) map);
082    }
083
084    //-----------------------------------------------------------------------
085    /**
086     * Write the map out using a custom routine.
087     *
088     * @param out  the output stream
089     * @throws IOException if an error occurs while writing to the stream
090     * @since 3.1
091     */
092    private void writeObject(final ObjectOutputStream out) throws IOException {
093        out.defaultWriteObject();
094        out.writeObject(map);
095    }
096
097    /**
098     * Read the map in using a custom routine.
099     *
100     * @param in  the input stream
101     * @throws IOException if an error occurs while reading from the stream
102     * @throws ClassNotFoundException if an object read from the stream can not be loaded
103     * @since 3.1
104     */
105    @SuppressWarnings("unchecked")
106    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
107        in.defaultReadObject();
108        map = (Map<K, V>) in.readObject();
109    }
110
111    //-----------------------------------------------------------------------
112    @Override
113    public void clear() {
114        throw new UnsupportedOperationException();
115    }
116
117    @Override
118    public V put(final K key, final V value) {
119        throw new UnsupportedOperationException();
120    }
121
122    @Override
123    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
124        throw new UnsupportedOperationException();
125    }
126
127    @Override
128    public V remove(final Object key) {
129        throw new UnsupportedOperationException();
130    }
131
132    @Override
133    public MapIterator<K, V> mapIterator() {
134        if (map instanceof IterableMap) {
135            final MapIterator<K, V> it = ((IterableMap<K, V>) map).mapIterator();
136            return UnmodifiableMapIterator.unmodifiableMapIterator(it);
137        }
138        final MapIterator<K, V> it = new EntrySetMapIterator<>(map);
139        return UnmodifiableMapIterator.unmodifiableMapIterator(it);
140    }
141
142    @Override
143    public Set<Map.Entry<K, V>> entrySet() {
144        final Set<Map.Entry<K, V>> set = super.entrySet();
145        return UnmodifiableEntrySet.unmodifiableEntrySet(set);
146    }
147
148    @Override
149    public Set<K> keySet() {
150        final Set<K> set = super.keySet();
151        return UnmodifiableSet.unmodifiableSet(set);
152    }
153
154    @Override
155    public Collection<V> values() {
156        final Collection<V> coll = super.values();
157        return UnmodifiableCollection.unmodifiableCollection(coll);
158    }
159
160}