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.set;
018
019import java.io.IOException;
020import java.io.ObjectInputStream;
021import java.io.ObjectOutputStream;
022import java.util.Collection;
023import java.util.Iterator;
024import java.util.SortedSet;
025
026import org.apache.commons.collections4.Unmodifiable;
027import org.apache.commons.collections4.iterators.UnmodifiableIterator;
028
029/**
030 * Decorates another <code>SortedSet</code> to ensure it can't be altered.
031 * <p>
032 * This class is Serializable from Commons Collections 3.1.
033 * <p>
034 * Attempts to modify it will result in an UnsupportedOperationException.
035 *
036 * @since 3.0
037 * @version $Id: UnmodifiableSortedSet.html 972397 2015-11-14 15:01:49Z tn $
038 */
039public final class UnmodifiableSortedSet<E>
040        extends AbstractSortedSetDecorator<E>
041        implements Unmodifiable {
042
043    /** Serialization version */
044    private static final long serialVersionUID = -725356885467962424L;
045
046    /**
047     * Factory method to create an unmodifiable set.
048     *
049     * @param <E> the element type
050     * @param set  the set to decorate, must not be null
051     * @return a new unmodifiable {@link SortedSet}
052     * @throws NullPointerException if set is null
053     * @since 4.0
054     */
055    public static <E> SortedSet<E> unmodifiableSortedSet(final SortedSet<E> set) {
056        if (set instanceof Unmodifiable) {
057            return set;
058        }
059        return new UnmodifiableSortedSet<E>(set);
060    }
061
062    //-----------------------------------------------------------------------
063    /**
064     * Constructor that wraps (not copies).
065     *
066     * @param set  the set to decorate, must not be null
067     * @throws NullPointerException if set is null
068     */
069    private UnmodifiableSortedSet(final SortedSet<E> set) {
070        super(set);
071    }
072
073    //-----------------------------------------------------------------------
074    @Override
075    public Iterator<E> iterator() {
076        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
077    }
078
079    @Override
080    public boolean add(final E object) {
081        throw new UnsupportedOperationException();
082    }
083
084    @Override
085    public boolean addAll(final Collection<? extends E> coll) {
086        throw new UnsupportedOperationException();
087    }
088
089    @Override
090    public void clear() {
091        throw new UnsupportedOperationException();
092    }
093
094    @Override
095    public boolean remove(final Object object) {
096        throw new UnsupportedOperationException();
097    }
098
099    @Override
100    public boolean removeAll(final Collection<?> coll) {
101        throw new UnsupportedOperationException();
102    }
103
104    @Override
105    public boolean retainAll(final Collection<?> coll) {
106        throw new UnsupportedOperationException();
107    }
108
109    //-----------------------------------------------------------------------
110    @Override
111    public SortedSet<E> subSet(final E fromElement, final E toElement) {
112        final SortedSet<E> sub = decorated().subSet(fromElement, toElement);
113        return unmodifiableSortedSet(sub);
114    }
115
116    @Override
117    public SortedSet<E> headSet(final E toElement) {
118        final SortedSet<E> head = decorated().headSet(toElement);
119        return unmodifiableSortedSet(head);
120    }
121
122    @Override
123    public SortedSet<E> tailSet(final E fromElement) {
124        final SortedSet<E> tail = decorated().tailSet(fromElement);
125        return unmodifiableSortedSet(tail);
126    }
127
128    //-----------------------------------------------------------------------
129    /**
130     * Write the collection out using a custom routine.
131     *
132     * @param out  the output stream
133     * @throws IOException
134     */
135    private void writeObject(final ObjectOutputStream out) throws IOException {
136        out.defaultWriteObject();
137        out.writeObject(decorated());
138    }
139
140    /**
141     * Read the collection in using a custom routine.
142     *
143     * @param in  the input stream
144     * @throws IOException
145     * @throws ClassNotFoundException
146     */
147    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
148    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
149        in.defaultReadObject();
150        setCollection((Collection<E>) in.readObject()); // (1)
151    }
152
153}