    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 *      https://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;
    025import java.util.function.Predicate;
    026
    027import org.apache.commons.collections4.Unmodifiable;
    028import org.apache.commons.collections4.iterators.UnmodifiableIterator;
    029
    030/**
    031 * Decorates another {@code SortedSet} to ensure it can't be altered.
    032 * <p>
    033 * This class is Serializable from Commons Collections 3.1.
    034 * </p>
    035 * <p>
    036 * Attempts to modify it will result in an UnsupportedOperationException.
    037 * </p>
    038 *
    039 * @param <E> The type of the elements in this set
    040 * @since 3.0
    041 */
    042public final class UnmodifiableSortedSet<E>
    043        extends AbstractSortedSetDecorator<E>
    044        implements Unmodifiable {
    045
    046    /** Serialization version */
    047    private static final long serialVersionUID = -725356885467962424L;
    048
    049    /**
    050     * Factory method to create an unmodifiable set.
    051     *
    052     * @param <E> The element type
    053     * @param set  The set to decorate, must not be null
    054     * @return A new unmodifiable {@link SortedSet}
    055     * @throws NullPointerException if set is null
    056     * @since 4.0
    057     */
    058    public static <E> SortedSet<E> unmodifiableSortedSet(final SortedSet<E> set) {
    059        if (set instanceof Unmodifiable) {
    060            return set;
    061        }
    062        return new UnmodifiableSortedSet<>(set);
    063    }
    064
    065    /**
    066     * Constructor that wraps (not copies).
    067     *
    068     * @param set  The set to decorate, must not be null
    069     * @throws NullPointerException if set is null
    070     */
    071    private UnmodifiableSortedSet(final SortedSet<E> set) {
    072        super(set);
    073    }
    074
    075    /**
    076     * Always throws {@link UnsupportedOperationException}.
    077     *
    078     * @param object Ignored.
    079     * @throws UnsupportedOperationException Always thrown.
    080     */
    081    @Override
    082    public boolean add(final E object) {
    083        throw new UnsupportedOperationException();
    084    }
    085
    086    /**
    087     * Always throws {@link UnsupportedOperationException}.
    088     *
    089     * @param coll Ignored.
    090     * @throws UnsupportedOperationException Always thrown.
    091     */
    092    @Override
    093    public boolean addAll(final Collection<? extends E> coll) {
    094        throw new UnsupportedOperationException();
    095    }
    096
    097    /**
    098     * Always throws {@link UnsupportedOperationException}.
    099     *
    100     * @throws UnsupportedOperationException Always thrown.
    101     */
    102    @Override
    103    public void clear() {
    104        throw new UnsupportedOperationException();
    105    }
    106
    107    @Override
    108    public SortedSet<E> headSet(final E toElement) {
    109        return unmodifiableSortedSet(decorated().headSet(toElement));
    110    }
    111
    112    @Override
    113    public Iterator<E> iterator() {
    114        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    115    }
    116
    117    /**
    118     * Deserializes the collection in using a custom routine.
    119     *
    120     * @param in  The input stream
    121     * @throws IOException Thrown if an error occurs while reading from the stream
    122     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
    123     */
    124    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    125    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    126        in.defaultReadObject();
    127        setCollection((Collection<E>) in.readObject()); // (1)
    128    }
    129
    130    /**
    131     * Always throws {@link UnsupportedOperationException}.
    132     *
    133     * @param object Ignored.
    134     * @throws UnsupportedOperationException Always thrown.
    135     */
    136    @Override
    137    public boolean remove(final Object object) {
    138        throw new UnsupportedOperationException();
    139    }
    140
    141    /**
    142     * Always throws {@link UnsupportedOperationException}.
    143     *
    144     * @param coll Ignored.
    145     * @throws UnsupportedOperationException Always thrown.
    146     */
    147    @Override
    148    public boolean removeAll(final Collection<?> coll) {
    149        throw new UnsupportedOperationException();
    150    }
    151
    152    /**
    153     * Always throws {@link UnsupportedOperationException}.
    154     *
    155     * @param filter Ignored.
    156     * @throws UnsupportedOperationException Always thrown.
    157     * @since 4.4
    158     */
    159    @Override
    160    public boolean removeIf(final Predicate<? super E> filter) {
    161        throw new UnsupportedOperationException();
    162    }
    163
    164    /**
    165     * Always throws {@link UnsupportedOperationException}.
    166     *
    167     * @throws UnsupportedOperationException Always thrown.
    168     */
    169    @Override
    170    public boolean retainAll(final Collection<?> coll) {
    171        throw new UnsupportedOperationException();
    172    }
    173
    174    @Override
    175    public SortedSet<E> subSet(final E fromElement, final E toElement) {
    176        return unmodifiableSortedSet(decorated().subSet(fromElement, toElement));
    177    }
    178
    179    @Override
    180    public SortedSet<E> tailSet(final E fromElement) {
    181        return unmodifiableSortedSet(decorated().tailSet(fromElement));
    182    }
    183
    184    /**
    185     * Serializes this object to an ObjectOutputStream.
    186     *
    187     * @param out The target ObjectOutputStream.
    188     * @throws IOException thrown when an I/O errors occur writing to the target stream.
    189     */
    190    private void writeObject(final ObjectOutputStream out) throws IOException {
    191        out.defaultWriteObject();
    192        out.writeObject(decorated());
    193    }
    194
    195}