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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.util; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * This class provides a skeletal implementation of the <tt>List</tt> | ||
| 30 | * interface to minimize the effort required to implement this interface | ||
| 31 | * backed by a "sequential access" data store (such as a linked list). For | ||
| 32 | * random access data (such as an array), <tt>AbstractList</tt> should be used | ||
| 33 | * in preference to this class.<p> | ||
| 34 | * | ||
| 35 | * This class is the opposite of the <tt>AbstractList</tt> class in the sense | ||
| 36 | * that it implements the "random access" methods (<tt>get(int index)</tt>, | ||
| 37 | * <tt>set(int index, E element)</tt>, <tt>add(int index, E element)</tt> and | ||
| 38 | * <tt>remove(int index)</tt>) on top of the list's list iterator, instead of | ||
| 39 | * the other way around.<p> | ||
| 40 | * | ||
| 41 | * To implement a list the programmer needs only to extend this class and | ||
| 42 | * provide implementations for the <tt>listIterator</tt> and <tt>size</tt> | ||
| 43 | * methods. For an unmodifiable list, the programmer need only implement the | ||
| 44 | * list iterator's <tt>hasNext</tt>, <tt>next</tt>, <tt>hasPrevious</tt>, | ||
| 45 | * <tt>previous</tt> and <tt>index</tt> methods.<p> | ||
| 46 | * | ||
| 47 | * For a modifiable list the programmer should additionally implement the list | ||
| 48 | * iterator's <tt>set</tt> method. For a variable-size list the programmer | ||
| 49 | * should additionally implement the list iterator's <tt>remove</tt> and | ||
| 50 | * <tt>add</tt> methods.<p> | ||
| 51 | * | ||
| 52 | * The programmer should generally provide a void (no argument) and collection | ||
| 53 | * constructor, as per the recommendation in the <tt>Collection</tt> interface | ||
| 54 | * specification.<p> | ||
| 55 | * | ||
| 56 | * This class is a member of the | ||
| 57 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 58 | * Java Collections Framework</a>. | ||
| 59 | * | ||
| 60 | * @author Josh Bloch | ||
| 61 | * @author Neal Gafter | ||
| 62 | * @see Collection | ||
| 63 | * @see List | ||
| 64 | * @see AbstractList | ||
| 65 | * @see AbstractCollection | ||
| 66 | * @since 1.2 | ||
| 67 | */ | ||
| 68 | |||
| 69 | public abstract class AbstractSequentialList<E> extends AbstractList<E> { | ||
| 70 | /** | ||
| 71 | * Sole constructor. (For invocation by subclass constructors, typically | ||
| 72 | * implicit.) | ||
| 73 | */ | ||
| 74 | protected AbstractSequentialList() { | ||
| 75 | } | ||
| 76 | |||
| 77 | /** | ||
| 78 | * Returns the element at the specified position in this list. | ||
| 79 | * | ||
| 80 | * <p>This implementation first gets a list iterator pointing to the | ||
| 81 | * indexed element (with <tt>listIterator(index)</tt>). Then, it gets | ||
| 82 | * the element using <tt>ListIterator.next</tt> and returns it. | ||
| 83 | * | ||
| 84 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 85 | */ | ||
| 86 | public E get(int index) { | ||
| 87 | try { | ||
| 88 | return listIterator(index).next(); | ||
| 89 | } catch (NoSuchElementException exc) { | ||
| 90 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 91 | } | ||
| 92 | } | ||
| 93 | |||
| 94 | /** | ||
| 95 | * Replaces the element at the specified position in this list with the | ||
| 96 | * specified element (optional operation). | ||
| 97 | * | ||
| 98 | * <p>This implementation first gets a list iterator pointing to the | ||
| 99 | * indexed element (with <tt>listIterator(index)</tt>). Then, it gets | ||
| 100 | * the current element using <tt>ListIterator.next</tt> and replaces it | ||
| 101 | * with <tt>ListIterator.set</tt>. | ||
| 102 | * | ||
| 103 | * <p>Note that this implementation will throw an | ||
| 104 | * <tt>UnsupportedOperationException</tt> if the list iterator does not | ||
| 105 | * implement the <tt>set</tt> operation. | ||
| 106 | * | ||
| 107 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 108 | * @throws ClassCastException {@inheritDoc} | ||
| 109 | * @throws NullPointerException {@inheritDoc} | ||
| 110 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 111 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 112 | */ | ||
| 113 | public E set(int index, E element) { | ||
| 114 | try { | ||
| 115 | ListIterator<E> e = listIterator(index); | ||
| 116 | E oldVal = e.next(); | ||
| 117 | e.set(element); | ||
| 118 | return oldVal; | ||
| 119 | } catch (NoSuchElementException exc) { | ||
| 120 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 121 | } | ||
| 122 | } | ||
| 123 | |||
| 124 | /** | ||
| 125 | * Inserts the specified element at the specified position in this list | ||
| 126 | * (optional operation). Shifts the element currently at that position | ||
| 127 | * (if any) and any subsequent elements to the right (adds one to their | ||
| 128 | * indices). | ||
| 129 | * | ||
| 130 | * <p>This implementation first gets a list iterator pointing to the | ||
| 131 | * indexed element (with <tt>listIterator(index)</tt>). Then, it | ||
| 132 | * inserts the specified element with <tt>ListIterator.add</tt>. | ||
| 133 | * | ||
| 134 | * <p>Note that this implementation will throw an | ||
| 135 | * <tt>UnsupportedOperationException</tt> if the list iterator does not | ||
| 136 | * implement the <tt>add</tt> operation. | ||
| 137 | * | ||
| 138 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 139 | * @throws ClassCastException {@inheritDoc} | ||
| 140 | * @throws NullPointerException {@inheritDoc} | ||
| 141 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 142 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 143 | */ | ||
| 144 | public void add(int index, E element) { | ||
| 145 | try { | ||
| 146 | listIterator(index).add(element); | ||
| 147 | } catch (NoSuchElementException exc) { | ||
| 148 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 149 | } | ||
| 150 | } | ||
| 151 | |||
| 152 | /** | ||
| 153 | * Removes the element at the specified position in this list (optional | ||
| 154 | * operation). Shifts any subsequent elements to the left (subtracts one | ||
| 155 | * from their indices). Returns the element that was removed from the | ||
| 156 | * list. | ||
| 157 | * | ||
| 158 | * <p>This implementation first gets a list iterator pointing to the | ||
| 159 | * indexed element (with <tt>listIterator(index)</tt>). Then, it removes | ||
| 160 | * the element with <tt>ListIterator.remove</tt>. | ||
| 161 | * | ||
| 162 | * <p>Note that this implementation will throw an | ||
| 163 | * <tt>UnsupportedOperationException</tt> if the list iterator does not | ||
| 164 | * implement the <tt>remove</tt> operation. | ||
| 165 | * | ||
| 166 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 167 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 168 | */ | ||
| 169 | public E remove(int index) { | ||
| 170 | try { | ||
| 171 | ListIterator<E> e = listIterator(index); | ||
| 172 | E outCast = e.next(); | ||
| 173 | e.remove(); | ||
| 174 | return outCast; | ||
| 175 | } catch (NoSuchElementException exc) { | ||
| 176 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 177 | } | ||
| 178 | } | ||
| 179 | |||
| 180 | |||
| 181 | // Bulk Operations | ||
| 182 | |||
| 183 | /** | ||
| 184 | * Inserts all of the elements in the specified collection into this | ||
| 185 | * list at the specified position (optional operation). Shifts the | ||
| 186 | * element currently at that position (if any) and any subsequent | ||
| 187 | * elements to the right (increases their indices). The new elements | ||
| 188 | * will appear in this list in the order that they are returned by the | ||
| 189 | * specified collection's iterator. The behavior of this operation is | ||
| 190 | * undefined if the specified collection is modified while the | ||
| 191 | * operation is in progress. (Note that this will occur if the specified | ||
| 192 | * collection is this list, and it's nonempty.) | ||
| 193 | * | ||
| 194 | * <p>This implementation gets an iterator over the specified collection and | ||
| 195 | * a list iterator over this list pointing to the indexed element (with | ||
| 196 | * <tt>listIterator(index)</tt>). Then, it iterates over the specified | ||
| 197 | * collection, inserting the elements obtained from the iterator into this | ||
| 198 | * list, one at a time, using <tt>ListIterator.add</tt> followed by | ||
| 199 | * <tt>ListIterator.next</tt> (to skip over the added element). | ||
| 200 | * | ||
| 201 | * <p>Note that this implementation will throw an | ||
| 202 | * <tt>UnsupportedOperationException</tt> if the list iterator returned by | ||
| 203 | * the <tt>listIterator</tt> method does not implement the <tt>add</tt> | ||
| 204 | * operation. | ||
| 205 | * | ||
| 206 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 207 | * @throws ClassCastException {@inheritDoc} | ||
| 208 | * @throws NullPointerException {@inheritDoc} | ||
| 209 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 210 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 211 | */ | ||
| 212 | public boolean addAll(int index, Collection<? extends E> c) { | ||
| 213 | try { | ||
| 214 | boolean modified = false; | ||
| 215 | ListIterator<E> e1 = listIterator(index); | ||
| 216 | Iterator<? extends E> e2 = c.iterator(); | ||
| 217 | while (e2.hasNext()) { | ||
| 218 | e1.add(e2.next()); | ||
| 219 | modified = true; | ||
| 220 | } | ||
| 221 | return modified; | ||
| 222 | } catch (NoSuchElementException exc) { | ||
| 223 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 224 | } | ||
| 225 | } | ||
| 226 | |||
| 227 | |||
| 228 | // Iterators | ||
| 229 | |||
| 230 | /** | ||
| 231 | * Returns an iterator over the elements in this list (in proper | ||
| 232 | * sequence).<p> | ||
| 233 | * | ||
| 234 | * This implementation merely returns a list iterator over the list. | ||
| 235 | * | ||
| 236 | * @return an iterator over the elements in this list (in proper sequence) | ||
| 237 | */ | ||
| 238 | public Iterator<E> iterator() { | ||
| 239 | return listIterator(); | ||
| 240 | } | ||
| 241 | |||
| 242 | /** | ||
| 243 | * Returns a list iterator over the elements in this list (in proper | ||
| 244 | * sequence). | ||
| 245 | * | ||
| 246 | * @param index index of first element to be returned from the list | ||
| 247 | * iterator (by a call to the <code>next</code> method) | ||
| 248 | * @return a list iterator over the elements in this list (in proper | ||
| 249 | * sequence) | ||
| 250 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 251 | */ | ||
| 252 | public abstract ListIterator<E> listIterator(int index); | ||
| 253 | } | ||