    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;
    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</code> 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    /**
    067     * Constructor that wraps (not copies).
    068     *
    069     * @param set  the set to decorate, must not be null
    070     * @throws NullPointerException if set is null
    071     */
    072    private UnmodifiableSortedSet(final SortedSet<E> set) {
    073        super(set);
    074    }
    075
    076    //-----------------------------------------------------------------------
    077    @Override
    078    public Iterator<E> iterator() {
    079        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    080    }
    081
    082    @Override
    083    public boolean add(final E object) {
    084        throw new UnsupportedOperationException();
    085    }
    086
    087    @Override
    088    public boolean addAll(final Collection<? extends E> coll) {
    089        throw new UnsupportedOperationException();
    090    }
    091
    092    @Override
    093    public void clear() {
    094        throw new UnsupportedOperationException();
    095    }
    096
    097    @Override
    098    public boolean remove(final Object object) {
    099        throw new UnsupportedOperationException();
    100    }
    101
    102    /**
    103     * @since 4.4
    104     */
    105    @Override
    106    public boolean removeIf(Predicate<? super E> filter) {
    107        throw new UnsupportedOperationException();
    108    }
    109
    110    @Override
    111    public boolean removeAll(final Collection<?> coll) {
    112        throw new UnsupportedOperationException();
    113    }
    114
    115    @Override
    116    public boolean retainAll(final Collection<?> coll) {
    117        throw new UnsupportedOperationException();
    118    }
    119
    120    //-----------------------------------------------------------------------
    121    @Override
    122    public SortedSet<E> subSet(final E fromElement, final E toElement) {
    123        final SortedSet<E> sub = decorated().subSet(fromElement, toElement);
    124        return unmodifiableSortedSet(sub);
    125    }
    126
    127    @Override
    128    public SortedSet<E> headSet(final E toElement) {
    129        final SortedSet<E> head = decorated().headSet(toElement);
    130        return unmodifiableSortedSet(head);
    131    }
    132
    133    @Override
    134    public SortedSet<E> tailSet(final E fromElement) {
    135        final SortedSet<E> tail = decorated().tailSet(fromElement);
    136        return unmodifiableSortedSet(tail);
    137    }
    138
    139    //-----------------------------------------------------------------------
    140    /**
    141     * Write the collection out using a custom routine.
    142     *
    143     * @param out  the output stream
    144     * @throws IOException if an error occurs while writing to the stream
    145     */
    146    private void writeObject(final ObjectOutputStream out) throws IOException {
    147        out.defaultWriteObject();
    148        out.writeObject(decorated());
    149    }
    150
    151    /**
    152     * Read the collection in using a custom routine.
    153     *
    154     * @param in  the input stream
    155     * @throws IOException if an error occurs while reading from the stream
    156     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    157     */
    158    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    159    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    160        in.defaultReadObject();
    161        setCollection((Collection<E>) in.readObject()); // (1)
    162    }
    163
    164}