    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</code> 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    /**
    067     * Constructor that wraps (not copies).
    068     *
    069     * @param list  the list to decorate, must not be null
    070     * @throws NullPointerException if list is null
    071     */
    072    @SuppressWarnings("unchecked") // safe to upcast
    073    public UnmodifiableList(final List<? extends E> list) {
    074        super((List<E>) list);
    075    }
    076
    077    //-----------------------------------------------------------------------
    078    @Override
    079    public Iterator<E> iterator() {
    080        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    081    }
    082
    083    @Override
    084    public boolean add(final Object object) {
    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 boolean remove(final Object object) {
    100        throw new UnsupportedOperationException();
    101    }
    102
    103    /**
    104     * @since 4.4
    105     */
    106    @Override
    107    public boolean removeIf(Predicate<? super E> filter) {
    108        throw new UnsupportedOperationException();
    109    }
    110
    111    @Override
    112    public boolean removeAll(final Collection<?> coll) {
    113        throw new UnsupportedOperationException();
    114    }
    115
    116    @Override
    117    public boolean retainAll(final Collection<?> coll) {
    118        throw new UnsupportedOperationException();
    119    }
    120
    121    //-----------------------------------------------------------------------
    122    @Override
    123    public ListIterator<E> listIterator() {
    124        return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator());
    125    }
    126
    127    @Override
    128    public ListIterator<E> listIterator(final int index) {
    129        return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator(index));
    130    }
    131
    132    @Override
    133    public void add(final int index, final E object) {
    134        throw new UnsupportedOperationException();
    135    }
    136
    137    @Override
    138    public boolean addAll(final int index, final Collection<? extends E> coll) {
    139        throw new UnsupportedOperationException();
    140    }
    141
    142    @Override
    143    public E remove(final int index) {
    144        throw new UnsupportedOperationException();
    145    }
    146
    147    @Override
    148    public E set(final int index, final E object) {
    149        throw new UnsupportedOperationException();
    150    }
    151
    152    @Override
    153    public List<E> subList(final int fromIndex, final int toIndex) {
    154        final List<E> sub = decorated().subList(fromIndex, toIndex);
    155        return new UnmodifiableList<>(sub);
    156    }
    157
    158}