    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.list;
    018
    019import java.util.Collection;
    020import java.util.Iterator;
    021import java.util.List;
    022import java.util.ListIterator;
    023import java.util.function.Predicate;
    024
    025import org.apache.commons.collections4.Unmodifiable;
    026import org.apache.commons.collections4.iterators.UnmodifiableIterator;
    027import org.apache.commons.collections4.iterators.UnmodifiableListIterator;
    028
    029/**
    030 * Decorates another {@code List} to ensure it can't be altered.
    031 * <p>
    032 * This class is Serializable from Commons Collections 3.1.
    033 * </p>
    034 * <p>
    035 * Attempts to modify it will result in an UnsupportedOperationException.
    036 * </p>
    037 *
    038 * @since 3.0
    039 */
    040public final class UnmodifiableList<E>
    041        extends AbstractSerializableListDecorator<E>
    042        implements Unmodifiable {
    043
    044    /** Serialization version */
    045    private static final long serialVersionUID = 6595182819922443652L;
    046
    047    /**
    048     * Factory method to create an unmodifiable list.
    049     *
    050     * @param <E> the type of the elements in the list
    051     * @param list  the list to decorate, must not be null
    052     * @return a new unmodifiable list
    053     * @throws NullPointerException if list is null
    054     * @since 4.0
    055     */
    056    public static <E> List<E> unmodifiableList(final List<? extends E> list) {
    057        if (list instanceof Unmodifiable) {
    058            @SuppressWarnings("unchecked") // safe to upcast
    059            final List<E> tmpList = (List<E>) list;
    060            return tmpList;
    061        }
    062        return new UnmodifiableList<>(list);
    063    }
    064
    065    /**
    066     * Constructor that wraps (not copies).
    067     *
    068     * @param list  the list to decorate, must not be null
    069     * @throws NullPointerException if list is null
    070     */
    071    @SuppressWarnings("unchecked") // safe to upcast
    072    public UnmodifiableList(final List<? extends E> list) {
    073        super((List<E>) list);
    074    }
    075
    076    @Override
    077    public void add(final int index, final E object) {
    078        throw new UnsupportedOperationException();
    079    }
    080
    081    @Override
    082    public boolean add(final Object object) {
    083        throw new UnsupportedOperationException();
    084    }
    085
    086    @Override
    087    public boolean addAll(final Collection<? extends E> coll) {
    088        throw new UnsupportedOperationException();
    089    }
    090
    091    @Override
    092    public boolean addAll(final int index, final Collection<? extends E> coll) {
    093        throw new UnsupportedOperationException();
    094    }
    095
    096    @Override
    097    public void clear() {
    098        throw new UnsupportedOperationException();
    099    }
    100
    101    @Override
    102    public Iterator<E> iterator() {
    103        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    104    }
    105
    106    @Override
    107    public ListIterator<E> listIterator() {
    108        return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator());
    109    }
    110
    111    @Override
    112    public ListIterator<E> listIterator(final int index) {
    113        return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator(index));
    114    }
    115
    116    @Override
    117    public E remove(final int index) {
    118        throw new UnsupportedOperationException();
    119    }
    120
    121    @Override
    122    public boolean remove(final Object object) {
    123        throw new UnsupportedOperationException();
    124    }
    125
    126    @Override
    127    public boolean removeAll(final Collection<?> coll) {
    128        throw new UnsupportedOperationException();
    129    }
    130
    131    /**
    132     * @since 4.4
    133     */
    134    @Override
    135    public boolean removeIf(final Predicate<? super E> filter) {
    136        throw new UnsupportedOperationException();
    137    }
    138
    139    @Override
    140    public boolean retainAll(final Collection<?> coll) {
    141        throw new UnsupportedOperationException();
    142    }
    143
    144    @Override
    145    public E set(final int index, final E object) {
    146        throw new UnsupportedOperationException();
    147    }
    148
    149    @Override
    150    public List<E> subList(final int fromIndex, final int toIndex) {
    151        final List<E> sub = decorated().subList(fromIndex, toIndex);
    152        return new UnmodifiableList<>(sub);
    153    }
    154
    155}