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.multiset;
018
019import java.io.IOException;
020import java.io.ObjectInputStream;
021import java.io.ObjectOutputStream;
022import java.util.Collection;
023import java.util.Iterator;
024import java.util.Set;
025import java.util.function.Predicate;
026
027import org.apache.commons.collections4.MultiSet;
028import org.apache.commons.collections4.Unmodifiable;
029import org.apache.commons.collections4.iterators.UnmodifiableIterator;
030import org.apache.commons.collections4.set.UnmodifiableSet;
031
032/**
033 * Decorates another {@link MultiSet} to ensure it can't be altered.
034 * <p>
035 * Attempts to modify it will result in an UnsupportedOperationException.
036 * </p>
037 *
038 * @param <E> the type held in the multiset
039 * @since 4.1
040 */
041public final class UnmodifiableMultiSet<E>
042        extends AbstractMultiSetDecorator<E> implements Unmodifiable {
043
044    /** Serialization version */
045    private static final long serialVersionUID = 20150611L;
046
047    /**
048     * Factory method to create an unmodifiable multiset.
049     * <p>
050     * If the multiset passed in is already unmodifiable, it is returned.
051     * </p>
052     *
053     * @param <E>  the type of the elements in the multiset
054     * @param multiset  the multiset to decorate, may not be null
055     * @return an unmodifiable MultiSet
056     * @throws NullPointerException if multiset is null
057     */
058    public static <E> MultiSet<E> unmodifiableMultiSet(final MultiSet<? extends E> multiset) {
059        if (multiset instanceof Unmodifiable) {
060            @SuppressWarnings("unchecked") // safe to upcast
061            final MultiSet<E> tmpMultiSet = (MultiSet<E>) multiset;
062            return tmpMultiSet;
063        }
064        return new UnmodifiableMultiSet<>(multiset);
065    }
066
067    /**
068     * Constructor that wraps (not copies).
069     *
070     * @param multiset  the multiset to decorate, may not be null
071     * @throws NullPointerException if multiset is null
072     */
073    @SuppressWarnings("unchecked") // safe to upcast
074    private UnmodifiableMultiSet(final MultiSet<? extends E> multiset) {
075        super((MultiSet<E>) multiset);
076    }
077
078    @Override
079    public boolean add(final E object) {
080        throw new UnsupportedOperationException();
081    }
082
083    @Override
084    public int add(final E object, final int count) {
085        throw new UnsupportedOperationException();
086    }
087
088    @Override
089    public boolean addAll(final Collection<? extends E> coll) {
090        throw new UnsupportedOperationException();
091    }
092
093    @Override
094    public void clear() {
095        throw new UnsupportedOperationException();
096    }
097
098    @Override
099    public Set<MultiSet.Entry<E>> entrySet() {
100        final Set<MultiSet.Entry<E>> set = decorated().entrySet();
101        return UnmodifiableSet.unmodifiableSet(set);
102    }
103
104    @Override
105    public Iterator<E> iterator() {
106        return UnmodifiableIterator.<E>unmodifiableIterator(decorated().iterator());
107    }
108
109    /**
110     * Deserializes the collection in using a custom routine.
111     *
112     * @param in  the input stream
113     * @throws IOException if an error occurs while reading from the stream
114     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
115     * @throws ClassCastException if deserialized object has wrong type
116     */
117    @SuppressWarnings("unchecked") // will throw CCE, see Javadoc
118    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
119        in.defaultReadObject();
120        setCollection((Collection<E>) in.readObject());
121    }
122
123    @Override
124    public boolean remove(final Object object) {
125        throw new UnsupportedOperationException();
126    }
127
128    @Override
129    public int remove(final Object object, final int count) {
130        throw new UnsupportedOperationException();
131    }
132
133    @Override
134    public boolean removeAll(final Collection<?> coll) {
135        throw new UnsupportedOperationException();
136    }
137
138    /**
139     * @since 4.4
140     */
141    @Override
142    public boolean removeIf(final Predicate<? super E> filter) {
143        throw new UnsupportedOperationException();
144    }
145
146    @Override
147    public boolean retainAll(final Collection<?> coll) {
148        throw new UnsupportedOperationException();
149    }
150
151    @Override
152    public int setCount(final E object, final int count) {
153        throw new UnsupportedOperationException();
154    }
155
156    @Override
157    public Set<E> uniqueSet() {
158        final Set<E> set = decorated().uniqueSet();
159        return UnmodifiableSet.unmodifiableSet(set);
160    }
161
162    /**
163     * Serializes this object to an ObjectOutputStream.
164     *
165     * @param out the target ObjectOutputStream.
166     * @throws IOException thrown when an I/O errors occur writing to the target stream.
167     */
168    private void writeObject(final ObjectOutputStream out) throws IOException {
169        out.defaultWriteObject();
170        out.writeObject(decorated());
171    }
172
173}