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}