J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | } |