    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;
    023
    024import org.apache.commons.collections4.BoundedCollection;
    025import org.apache.commons.collections4.iterators.AbstractListIteratorDecorator;
    026import org.apache.commons.collections4.iterators.UnmodifiableIterator;
    027
    028/**
    029 * Decorates another <code>List</code> to fix the size preventing add/remove.
    030 * <p>
    031 * The add, remove, clear and retain operations are unsupported.
    032 * The set method is allowed (as it doesn't change the list size).
    033 * <p>
    034 * This class is Serializable from Commons Collections 3.1.
    035 *
    036 * @param <E> the type of elements in this collection
    037 * @since 3.0
    038 */
    039public class FixedSizeList<E>
    040        extends AbstractSerializableListDecorator<E>
    041        implements BoundedCollection<E> {
    042
    043    /** Serialization version */
    044    private static final long serialVersionUID = -2218010673611160319L;
    045
    046    /**
    047     * Factory method to create a fixed size list.
    048     *
    049     * @param <E> the type of the elements in the list
    050     * @param list  the list to decorate, must not be null
    051     * @return a new fixed size list
    052     * @throws NullPointerException if list is null
    053     * @since 4.0
    054     */
    055    public static <E> FixedSizeList<E> fixedSizeList(final List<E> list) {
    056        return new FixedSizeList<>(list);
    057    }
    058
    059    //-----------------------------------------------------------------------
    060    /**
    061     * Constructor that wraps (not copies).
    062     *
    063     * @param list  the list to decorate, must not be null
    064     * @throws NullPointerException if list is null
    065     */
    066    protected FixedSizeList(final List<E> list) {
    067        super(list);
    068    }
    069
    070    //-----------------------------------------------------------------------
    071    @Override
    072    public boolean add(final E object) {
    073        throw new UnsupportedOperationException("List is fixed size");
    074    }
    075
    076    @Override
    077    public void add(final int index, final E object) {
    078        throw new UnsupportedOperationException("List is fixed size");
    079    }
    080
    081    @Override
    082    public boolean addAll(final Collection<? extends E> coll) {
    083        throw new UnsupportedOperationException("List is fixed size");
    084    }
    085
    086    @Override
    087    public boolean addAll(final int index, final Collection<? extends E> coll) {
    088        throw new UnsupportedOperationException("List is fixed size");
    089    }
    090
    091    @Override
    092    public void clear() {
    093        throw new UnsupportedOperationException("List is fixed size");
    094    }
    095
    096    @Override
    097    public E get(final int index) {
    098        return decorated().get(index);
    099    }
    100
    101    @Override
    102    public int indexOf(final Object object) {
    103        return decorated().indexOf(object);
    104    }
    105
    106    @Override
    107    public Iterator<E> iterator() {
    108        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    109    }
    110
    111    @Override
    112    public int lastIndexOf(final Object object) {
    113        return decorated().lastIndexOf(object);
    114    }
    115
    116    @Override
    117    public ListIterator<E> listIterator() {
    118        return new FixedSizeListIterator(decorated().listIterator(0));
    119    }
    120
    121    @Override
    122    public ListIterator<E> listIterator(final int index) {
    123        return new FixedSizeListIterator(decorated().listIterator(index));
    124    }
    125
    126    @Override
    127    public E remove(final int index) {
    128        throw new UnsupportedOperationException("List is fixed size");
    129    }
    130
    131    @Override
    132    public boolean remove(final Object object) {
    133        throw new UnsupportedOperationException("List is fixed size");
    134    }
    135
    136    @Override
    137    public boolean removeAll(final Collection<?> coll) {
    138        throw new UnsupportedOperationException("List is fixed size");
    139    }
    140
    141    @Override
    142    public boolean retainAll(final Collection<?> coll) {
    143        throw new UnsupportedOperationException("List is fixed size");
    144    }
    145
    146    @Override
    147    public E set(final int index, final E object) {
    148        return decorated().set(index, object);
    149    }
    150
    151    @Override
    152    public List<E> subList(final int fromIndex, final int toIndex) {
    153        final List<E> sub = decorated().subList(fromIndex, toIndex);
    154        return new FixedSizeList<>(sub);
    155    }
    156
    157    /**
    158     * List iterator that only permits changes via set()
    159     */
    160    private class FixedSizeListIterator extends AbstractListIteratorDecorator<E> {
    161        protected FixedSizeListIterator(final ListIterator<E> iterator) {
    162            super(iterator);
    163        }
    164        @Override
    165        public void remove() {
    166            throw new UnsupportedOperationException("List is fixed size");
    167        }
    168        @Override
    169        public void add(final Object object) {
    170            throw new UnsupportedOperationException("List is fixed size");
    171        }
    172    }
    173
    174    @Override
    175    public boolean isFull() {
    176        return true;
    177    }
    178
    179    @Override
    180    public int maxSize() {
    181        return size();
    182    }
    183
    184}