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Comparing jsr166/src/main/java/util/Deque.java (file contents):
Revision 1.4 by dl, Tue Mar 22 16:48:32 2005 UTC vs.
Revision 1.19 by jsr166, Sun May 28 23:36:29 2006 UTC

# Line 25 | Line 25 | package java.util;
25   * operations cannot fail.
26   *
27   * <p>The twelve methods described above are summarized in the
28 < * following table:<p>
28 > * following table:
29   *
30 + * <p>
31   * <table BORDER CELLPADDING=3 CELLSPACING=1>
32   *  <tr>
33   *    <td></td>
# Line 36 | Line 37 | package java.util;
37   *  <tr>
38   *    <td></td>
39   *    <td ALIGN=CENTER><em>Throws exception</em></td>
40 < *    <td ALIGN=CENTER><em>Returns special value</em></td>
40 > *    <td ALIGN=CENTER><em>Special value</em></td>
41   *    <td ALIGN=CENTER><em>Throws exception</em></td>
42 < *    <td ALIGN=CENTER><em>Returns special value</em></td>
42 > *    <td ALIGN=CENTER><em>Special value</em></td>
43   *  </tr>
44   *  <tr>
45   *    <td><b>Insert</b></td>
# Line 67 | Line 68 | package java.util;
68   * used as a queue, FIFO (First-In-First-Out) behavior results.  Elements are
69   * added at the end of the deque and removed from the beginning.  The methods
70   * inherited from the <tt>Queue</tt> interface are precisely equivalent to
71 < * <tt>Deque</tt> methods as indicated in the following table:<p>
71 > * <tt>Deque</tt> methods as indicated in the following table:
72   *
73 + * <p>
74   * <table BORDER CELLPADDING=3 CELLSPACING=1>
75   *  <tr>
76   *    <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td>
77   *    <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
78   *  </tr>
79   *  <tr>
78 *   <tr>
79 *    <td>{@link java.util.Queue#offer offer(e)}</td>
80 *    <td>{@link #offerLast offerLast(e)}</td>
81 *   </tr>
82 *   <tr>
80   *    <td>{@link java.util.Queue#add add(e)}</td>
81   *    <td>{@link #addLast addLast(e)}</td>
82 < *   </tr>
83 < *   <tr>
84 < *    <td>{@link java.util.Queue#poll poll()}</td>
85 < *    <td>{@link #pollFirst pollFirst()}</td>
86 < *   </tr>
87 < *   <tr>
82 > *  </tr>
83 > *  <tr>
84 > *    <td>{@link java.util.Queue#offer offer(e)}</td>
85 > *    <td>{@link #offerLast offerLast(e)}</td>
86 > *  </tr>
87 > *  <tr>
88   *    <td>{@link java.util.Queue#remove remove()}</td>
89   *    <td>{@link #removeFirst removeFirst()}</td>
90 < *   </tr>
91 < *   <tr>
92 < *    <td>{@link java.util.Queue#peek peek()}</td>
93 < *    <td>{@link #peek peekFirst()}</td>
94 < *   </tr>
95 < *   <tr>
90 > *  </tr>
91 > *  <tr>
92 > *    <td>{@link java.util.Queue#poll poll()}</td>
93 > *    <td>{@link #pollFirst pollFirst()}</td>
94 > *  </tr>
95 > *  <tr>
96   *    <td>{@link java.util.Queue#element element()}</td>
97   *    <td>{@link #getFirst getFirst()}</td>
98 < *   </tr>
98 > *  </tr>
99 > *  <tr>
100 > *    <td>{@link java.util.Queue#peek peek()}</td>
101 > *    <td>{@link #peek peekFirst()}</td>
102 > *  </tr>
103   * </table>
104   *
105   * <p>Deques can also be used as LIFO (Last-In-First-Out) stacks.  This
106   * interface should be used in preference to the legacy {@link Stack} class.
107   * When a deque is used as a stack, elements are pushed and popped from the
108   * beginning of the deque.  Stack methods are precisely equivalent to
109 < * <tt>Deque</tt> methods as indicated in the table below:<p>
109 > * <tt>Deque</tt> methods as indicated in the table below:
110   *
111 + * <p>
112   * <table BORDER CELLPADDING=3 CELLSPACING=1>
113   *  <tr>
114   *    <td ALIGN=CENTER> <b>Stack Method</b></td>
115   *    <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
116   *  </tr>
117   *  <tr>
116 *   <tr>
118   *    <td>{@link #push push(e)}</td>
119   *    <td>{@link #addFirst addFirst(e)}</td>
120 < *   </tr>
121 < *   <tr>
120 > *  </tr>
121 > *  <tr>
122   *    <td>{@link #pop pop()}</td>
123   *    <td>{@link #removeFirst removeFirst()}</td>
124 < *   </tr>
125 < *   <tr>
124 > *  </tr>
125 > *  <tr>
126   *    <td>{@link #peek peek()}</td>
127   *    <td>{@link #peekFirst peekFirst()}</td>
128 < *   </tr>
128 > *  </tr>
129   * </table>
130   *
131   * <p>Note that the {@link #peek peek} method works equally well when
# Line 133 | Line 134 | package java.util;
134   *
135   * <p>This interface provides two methods to remove interior
136   * elements, {@link #removeFirstOccurrence removeFirstOccurrence} and
137 < * {@link #removeLastOccurrence removeLastOccurrence}.  Unlike the
138 < * {@link List} interface, this interface does not provide support for
139 < * indexed access to elements.
137 > * {@link #removeLastOccurrence removeLastOccurrence}.
138 > *
139 > * <p>Unlike the {@link List} interface, this interface does not
140 > * provide support for indexed access to elements.
141   *
142   * <p>While <tt>Deque</tt> implementations are not strictly required
143   * to prohibit the insertion of null elements, they are strongly
# Line 151 | Line 153 | package java.util;
153   * <tt>Object</tt>.
154   *
155   * <p>This interface is a member of the <a
156 < * href="{@docRoot}/../guide/collections/index.html"> Java Collections
156 > * href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections
157   * Framework</a>.
158   *
159   * @author Doug Lea
# Line 162 | Line 164 | package java.util;
164  
165   public interface Deque<E> extends Queue<E> {
166      /**
167 +     * Inserts the specified element at the front of this deque if it is
168 +     * possible to do so immediately without violating capacity restrictions.
169 +     * When using a capacity-restricted deque, it is generally preferable to
170 +     * use method {@link #offerFirst}.
171 +     *
172 +     * @param e the element to add
173 +     * @throws IllegalStateException if the element cannot be added at this
174 +     *         time due to capacity restrictions
175 +     * @throws ClassCastException if the class of the specified element
176 +     *         prevents it from being added to this deque
177 +     * @throws NullPointerException if the specified element is null and this
178 +     *         deque does not permit null elements
179 +     * @throws IllegalArgumentException if some property of the specified
180 +     *         element prevents it from being added to this deque
181 +     */
182 +    void addFirst(E e);
183 +
184 +    /**
185 +     * Inserts the specified element at the end of this deque if it is
186 +     * possible to do so immediately without violating capacity restrictions.
187 +     * When using a capacity-restricted deque, it is generally preferable to
188 +     * use method {@link #offerLast}.
189 +     *
190 +     * <p>This method is equivalent to {@link #add}.
191 +     *
192 +     * @param e the element to add
193 +     * @throws IllegalStateException if the element cannot be added at this
194 +     *         time due to capacity restrictions
195 +     * @throws ClassCastException if the class of the specified element
196 +     *         prevents it from being added to this deque
197 +     * @throws NullPointerException if the specified element is null and this
198 +     *         deque does not permit null elements
199 +     * @throws IllegalArgumentException if some property of the specified
200 +     *         element prevents it from being added to this deque
201 +     */
202 +    void addLast(E e);
203 +
204 +    /**
205       * Inserts the specified element at the front of this deque unless it would
206       * violate capacity restrictions.  When using a capacity-restricted deque,
207 <     * this method is generally preferable to method <tt>addFirst</tt>, which
208 <     * can fail to insert an element only by throwing an exception.
207 >     * this method is generally preferable to the {@link #addFirst} method,
208 >     * which can fail to insert an element only by throwing an exception.
209       *
210 <     * @param e the element to insert
211 <     * @return <tt>true</tt> if it was possible to insert the element,
212 <     *     else <tt>false</tt>
210 >     * @param e the element to add
211 >     * @return <tt>true</tt> if the element was added to this deque, else
212 >     *         <tt>false</tt>
213 >     * @throws ClassCastException if the class of the specified element
214 >     *         prevents it from being added to this deque
215       * @throws NullPointerException if the specified element is null and this
216 <     *     deque does not permit null elements
216 >     *         deque does not permit null elements
217 >     * @throws IllegalArgumentException if some property of the specified
218 >     *         element prevents it from being added to this deque
219       */
220      boolean offerFirst(E e);
221  
222      /**
223       * Inserts the specified element at the end of this deque unless it would
224       * violate capacity restrictions.  When using a capacity-restricted deque,
225 <     * this method is generally preferable to method <tt>addLast</tt> which
226 <     * can fail to insert an element only by throwing an exception.
225 >     * this method is generally preferable to the {@link #addLast} method,
226 >     * which can fail to insert an element only by throwing an exception.
227       *
228 <     * @param e the element to insert
229 <     * @return <tt>true</tt> if it was possible to insert the element,
230 <     *     else <tt>false</tt>
228 >     * @param e the element to add
229 >     * @return <tt>true</tt> if the element was added to this deque, else
230 >     *         <tt>false</tt>
231 >     * @throws ClassCastException if the class of the specified element
232 >     *         prevents it from being added to this deque
233       * @throws NullPointerException if the specified element is null and this
234 <     *     deque does not permit null elements
234 >     *         deque does not permit null elements
235 >     * @throws IllegalArgumentException if some property of the specified
236 >     *         element prevents it from being added to this deque
237       */
238      boolean offerLast(E e);
239  
240      /**
241 <     * Inserts the specified element at the front of this deque unless it
242 <     * would violate capacity restrictions.
241 >     * Retrieves and removes the first element of this deque.  This method
242 >     * differs from {@link #pollFirst pollFirst} only in that it throws an
243 >     * exception if this deque is empty.
244       *
245 <     * @param e the element to insert
246 <     * @throws IllegalStateException if it was not possible to insert
198 <     *    the element due to capacity restrictions
199 <     * @throws NullPointerException if the specified element is null and this
200 <     *     deque does not permit null elements
245 >     * @return the head of this deque
246 >     * @throws NoSuchElementException if this deque is empty
247       */
248 <    void addFirst(E e);
248 >    E removeFirst();
249  
250      /**
251 <     * Inserts the specified element at the end of this deque unless it would
252 <     * violate capacity restrictions.
251 >     * Retrieves and removes the last element of this deque.  This method
252 >     * differs from {@link #pollLast pollLast} only in that it throws an
253 >     * exception if this deque is empty.
254       *
255 <     * @param e the element to insert
256 <     * @throws IllegalStateException if it was not possible to insert
210 <     *    the element due to capacity restrictions
211 <     * @throws NullPointerException if the specified element is null and this
212 <     *     deque does not permit null elements
255 >     * @return the tail of this deque
256 >     * @throws NoSuchElementException if this deque is empty
257       */
258 <    void addLast(E e);
258 >    E removeLast();
259  
260      /**
261 <     * Retrieves and removes the first element of this deque, or
262 <     * <tt>null</tt> if this deque is empty.
261 >     * Retrieves and removes the first element of this deque,
262 >     * or returns <tt>null</tt> if this deque is empty.
263       *
264 <     * @return the first element of this deque, or <tt>null</tt> if
221 <     *     this deque is empty
264 >     * @return the head of this deque, or <tt>null</tt> if this deque is empty
265       */
266      E pollFirst();
267  
268      /**
269 <     * Retrieves and removes the last element of this deque, or
270 <     * <tt>null</tt> if this deque is empty.
269 >     * Retrieves and removes the last element of this deque,
270 >     * or returns <tt>null</tt> if this deque is empty.
271       *
272 <     * @return the last element of this deque, or <tt>null</tt> if
230 <     *     this deque is empty
272 >     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
273       */
274      E pollLast();
275  
276      /**
277 <     * Removes and returns the first element of this deque.  This method
236 <     * differs from the <tt>pollFirst</tt> method only in that it throws an
237 <     * exception if this deque is empty.
277 >     * Retrieves, but does not remove, the first element of this deque.
278       *
279 <     * @return the first element of this deque
279 >     * This method differs from {@link #peekFirst peekFirst} only in that it
280 >     * throws an exception if this deque is empty.
281 >     *
282 >     * @return the head of this deque
283       * @throws NoSuchElementException if this deque is empty
284       */
285 <    E removeFirst();
285 >    E getFirst();
286  
287      /**
288 <     * Retrieves and removes the last element of this deque.  This method
289 <     * differs from the <tt>pollLast</tt> method only in that it throws an
290 <     * exception if this deque is empty.
288 >     * Retrieves, but does not remove, the last element of this deque.
289 >     * This method differs from {@link #peekLast peekLast} only in that it
290 >     * throws an exception if this deque is empty.
291       *
292 <     * @return the last element of this deque
292 >     * @return the tail of this deque
293       * @throws NoSuchElementException if this deque is empty
294       */
295 <    E removeLast();
295 >    E getLast();
296  
297      /**
298       * Retrieves, but does not remove, the first element of this deque,
299 <     * returning <tt>null</tt> if this deque is empty.
299 >     * or returns <tt>null</tt> if this deque is empty.
300       *
301 <     * @return the first element of this deque, or <tt>null</tt> if
259 <     *     this deque is empty
301 >     * @return the head of this deque, or <tt>null</tt> if this deque is empty
302       */
303      E peekFirst();
304  
305      /**
306       * Retrieves, but does not remove, the last element of this deque,
307 <     * returning <tt>null</tt> if this deque is empty.
307 >     * or returns <tt>null</tt> if this deque is empty.
308       *
309 <     * @return the last element of this deque, or <tt>null</tt> if this deque
268 <     *     is empty
309 >     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
310       */
311      E peekLast();
312  
313      /**
314 <     * Retrieves, but does not remove, the first element of this
315 <     * deque.  This method differs from the <tt>peekFirst</tt> method only
316 <     * in that it throws an exception if this deque is empty.
317 <     *
318 <     * @return the first element of this deque
319 <     * @throws NoSuchElementException if this deque is empty
320 <     */
280 <    E getFirst();
281 <
282 <    /**
283 <     * Retrieves, but does not remove, the last element of this
284 <     * deque.  This method differs from the <tt>peekLast</tt> method only
285 <     * in that it throws an exception if this deque is empty.
286 <     *
287 <     * @return the last element of this deque
288 <     * @throws NoSuchElementException if this deque is empty
289 <     */
290 <    E getLast();
291 <
292 <    /**
293 <     * Removes the first occurrence of the specified element in this
294 <     * deque.  If the deque does not contain the element, it is
295 <     * unchanged.  More formally, removes the first element <tt>e</tt>
296 <     * such that <tt>(o==null ? e==null : o.equals(e))</tt> (if
297 <     * such an element exists).
314 >     * Removes the first occurrence of the specified element from this deque.
315 >     * If the deque does not contain the element, it is unchanged.
316 >     * More formally, removes the first element <tt>e</tt> such that
317 >     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
318 >     * (if such an element exists).
319 >     * Returns <tt>true</tt> if this deque contained the specified element
320 >     * (or equivalently, if this deque changed as a result of the call).
321       *
322       * @param o element to be removed from this deque, if present
323 <     * @return <tt>true</tt> if the deque contained the specified element
323 >     * @return <tt>true</tt> if an element was removed as a result of this call
324 >     * @throws ClassCastException if the class of the specified element
325 >     *         is incompatible with this deque (optional)
326       * @throws NullPointerException if the specified element is null and this
327 <     *     deque does not permit null elements
327 >     *         deque does not permit null elements (optional)
328       */
329      boolean removeFirstOccurrence(Object o);
330  
331      /**
332 <     * Removes the last occurrence of the specified element in this
333 <     * deque.  If the deque does not contain the element, it is
334 <     * unchanged.  More formally, removes the last element <tt>e</tt>
335 <     * such that <tt>(o==null ? e==null : o.equals(e))</tt> (if
336 <     * such an element exists).
332 >     * Removes the last occurrence of the specified element from this deque.
333 >     * If the deque does not contain the element, it is unchanged.
334 >     * More formally, removes the last element <tt>e</tt> such that
335 >     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
336 >     * (if such an element exists).
337 >     * Returns <tt>true</tt> if this deque contained the specified element
338 >     * (or equivalently, if this deque changed as a result of the call).
339       *
340       * @param o element to be removed from this deque, if present
341 <     * @return <tt>true</tt> if the deque contained the specified element
341 >     * @return <tt>true</tt> if an element was removed as a result of this call
342 >     * @throws ClassCastException if the class of the specified element
343 >     *         is incompatible with this deque (optional)
344       * @throws NullPointerException if the specified element is null and this
345 <     *     deque does not permit null elements
345 >     *         deque does not permit null elements (optional)
346       */
347      boolean removeLastOccurrence(Object o);
348  
320
349      // *** Queue methods ***
350  
351      /**
352       * Inserts the specified element into the queue represented by this deque
353 <     * unless it would violate capacity restrictions.  In other words, inserts
354 <     * the specified element at the end of this deque.  When using a
355 <     * capacity-restricted deque, this method is generally preferable to the
356 <     * {@link #add} method, which can fail to insert an element only by
357 <     * throwing an exception.
358 <     *
331 <     * <p>This method is equivalent to {@link #offerLast}.
332 <     *
333 <     * @param e the element to insert
334 <     * @return <tt>true</tt> if it was possible to insert the element,
335 <     *     else <tt>false</tt>
336 <     * @throws NullPointerException if the specified element is null and this
337 <     *     deque does not permit null elements
338 <     */
339 <    boolean offer(E e);
340 <
341 <    /**
342 <     * Inserts the specified element into the queue represented by this
343 <     * deque unless it would violate capacity restrictions.  In other words,
344 <     * inserts the specified element as the last element of this deque.
353 >     * (in other words, at the tail of this deque) if it is possible to do so
354 >     * immediately without violating capacity restrictions, returning
355 >     * <tt>true</tt> upon success and throwing an
356 >     * <tt>IllegalStateException</tt> if no space is currently available.
357 >     * When using a capacity-restricted deque, it is generally preferable to
358 >     * use {@link #offer(Object) offer}.
359       *
360       * <p>This method is equivalent to {@link #addLast}.
361       *
362 <     * @param e the element to insert
363 <     * @return <tt>true</tt> (as per the spec for {@link Collection#add})
364 <     * @throws IllegalStateException if it was not possible to insert
365 <     *    the element due to capacity restrictions
362 >     * @param e the element to add
363 >     * @return <tt>true</tt> (as specified by {@link Collection#add})
364 >     * @throws IllegalStateException if the element cannot be added at this
365 >     *         time due to capacity restrictions
366 >     * @throws ClassCastException if the class of the specified element
367 >     *         prevents it from being added to this deque
368       * @throws NullPointerException if the specified element is null and this
369 <     *     deque does not permit null elements
369 >     *         deque does not permit null elements
370 >     * @throws IllegalArgumentException if some property of the specified
371 >     *         element prevents it from being added to this deque
372       */
373      boolean add(E e);
374  
375      /**
376 <     * Retrieves and removes the head of the queue represented by
377 <     * this deque, or <tt>null</tt> if this deque is empty.  In other words,
378 <     * retrieves and removes the first element of this deque, or <tt>null</tt>
379 <     * if this deque is empty.
376 >     * Inserts the specified element into the queue represented by this deque
377 >     * (in other words, at the tail of this deque) if it is possible to do so
378 >     * immediately without violating capacity restrictions, returning
379 >     * <tt>true</tt> upon success and <tt>false</tt> if no space is currently
380 >     * available.  When using a capacity-restricted deque, this method is
381 >     * generally preferable to the {@link #add} method, which can fail to
382 >     * insert an element only by throwing an exception.
383       *
384 <     * <p>This method is equivalent to {@link #pollFirst()}.
384 >     * <p>This method is equivalent to {@link #offerLast}.
385       *
386 <     * @return the first element of this deque, or <tt>null</tt> if
387 <     *     this deque is empty
386 >     * @param e the element to add
387 >     * @return <tt>true</tt> if the element was added to this deque, else
388 >     *         <tt>false</tt>
389 >     * @throws ClassCastException if the class of the specified element
390 >     *         prevents it from being added to this deque
391 >     * @throws NullPointerException if the specified element is null and this
392 >     *         deque does not permit null elements
393 >     * @throws IllegalArgumentException if some property of the specified
394 >     *         element prevents it from being added to this deque
395       */
396 <    E poll();
396 >    boolean offer(E e);
397  
398      /**
399 <     * Retrieves and removes the head of the queue represented by this deque.
400 <     * This method differs from the <tt>poll</tt> method only in that it
401 <     * throws an exception if this deque is empty.
399 >     * Retrieves and removes the head of the queue represented by this deque
400 >     * (in other words, the first element of this deque).
401 >     * This method differs from {@link #poll poll} only in that it throws an
402 >     * exception if this deque is empty.
403       *
404       * <p>This method is equivalent to {@link #removeFirst()}.
405       *
# Line 380 | Line 409 | public interface Deque<E> extends Queue<
409      E remove();
410  
411      /**
412 <     * Retrieves, but does not remove, the head of the queue represented by
413 <     * this deque, returning <tt>null</tt> if this deque is empty.
412 >     * Retrieves and removes the head of the queue represented by this deque
413 >     * (in other words, the first element of this deque), or returns
414 >     * <tt>null</tt> if this deque is empty.
415       *
416 <     * <p>This method is equivalent to {@link #peekFirst()}.
416 >     * <p>This method is equivalent to {@link #pollFirst()}.
417       *
418 <     * @return the head of the queue represented by this deque, or
419 <     *     <tt>null</tt> if this deque is empty
418 >     * @return the first element of this deque, or <tt>null</tt> if
419 >     *         this deque is empty
420       */
421 <    E peek();
421 >    E poll();
422  
423      /**
424       * Retrieves, but does not remove, the head of the queue represented by
425 <     * this deque.  This method differs from the <tt>peek</tt> method only in
426 <     * that it throws an exception if this deque is empty.
425 >     * this deque (in other words, the first element of this deque).
426 >     * This method differs from {@link #peek peek} only in that it throws an
427 >     * exception if this deque is empty.
428       *
429       * <p>This method is equivalent to {@link #getFirst()}.
430       *
# Line 402 | Line 433 | public interface Deque<E> extends Queue<
433       */
434      E element();
435  
436 +    /**
437 +     * Retrieves, but does not remove, the head of the queue represented by
438 +     * this deque (in other words, the first element of this deque), or
439 +     * returns <tt>null</tt> if this deque is empty.
440 +     *
441 +     * <p>This method is equivalent to {@link #peekFirst()}.
442 +     *
443 +     * @return the head of the queue represented by this deque, or
444 +     *         <tt>null</tt> if this deque is empty
445 +     */
446 +    E peek();
447 +
448  
449      // *** Stack methods ***
450  
451      /**
452 <     * Pushes an element onto the stack represented by this deque.  In other
453 <     * words, inserts the element at the front of this deque unless it would
454 <     * violate capacity restrictions.
452 >     * Pushes an element onto the stack represented by this deque (in other
453 >     * words, at the head of this deque) if it is possible to do so
454 >     * immediately without violating capacity restrictions, returning
455 >     * <tt>true</tt> upon success and throwing an
456 >     * <tt>IllegalStateException</tt> if no space is currently available.
457       *
458       * <p>This method is equivalent to {@link #addFirst}.
459       *
460       * @param e the element to push
461 <     * @throws IllegalStateException if it was not possible to insert
462 <     *    the element due to capacity restrictions
461 >     * @throws IllegalStateException if the element cannot be added at this
462 >     *         time due to capacity restrictions
463 >     * @throws ClassCastException if the class of the specified element
464 >     *         prevents it from being added to this deque
465       * @throws NullPointerException if the specified element is null and this
466 <     *     deque does not permit null elements
466 >     *         deque does not permit null elements
467 >     * @throws IllegalArgumentException if some property of the specified
468 >     *         element prevents it from being added to this deque
469       */
470      void push(E e);
471  
# Line 427 | Line 476 | public interface Deque<E> extends Queue<
476       * <p>This method is equivalent to {@link #removeFirst()}.
477       *
478       * @return the element at the front of this deque (which is the top
479 <     *     of the stack represented by this deque)
479 >     *         of the stack represented by this deque)
480       * @throws NoSuchElementException if this deque is empty
481       */
482      E pop();
483  
484  
485 <    // *** Collection Method ***
485 >    // *** Collection methods ***
486  
487      /**
488 <     * Returns an iterator over the elements in this deque.  The elements
489 <     * will be ordered from first (head) to last (tail).
488 >     * Removes the first occurrence of the specified element from this deque.
489 >     * If the deque does not contain the element, it is unchanged.
490 >     * More formally, removes the first element <tt>e</tt> such that
491 >     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
492 >     * (if such an element exists).
493 >     * Returns <tt>true</tt> if this deque contained the specified element
494 >     * (or equivalently, if this deque changed as a result of the call).
495 >     *
496 >     * <p>This method is equivalent to {@link #removeFirstOccurrence}.
497       *
498 <     * @return an <tt>Iterator</tt> over the elements in this deque
498 >     * @param o element to be removed from this deque, if present
499 >     * @return <tt>true</tt> if an element was removed as a result of this call
500 >     * @throws ClassCastException if the class of the specified element
501 >     *         is incompatible with this deque (optional)
502 >     * @throws NullPointerException if the specified element is null and this
503 >     *         deque does not permit null elements (optional)
504 >     */
505 >    boolean remove(Object o);
506 >
507 >    /**
508 >     * Returns <tt>true</tt> if this deque contains the specified element.
509 >     * More formally, returns <tt>true</tt> if and only if this deque contains
510 >     * at least one element <tt>e</tt> such that
511 >     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
512 >     *
513 >     * @param o element whose presence in this deque is to be tested
514 >     * @return <tt>true</tt> if this deque contains the specified element
515 >     * @throws ClassCastException if the type of the specified element
516 >     *         is incompatible with this deque (optional)
517 >     * @throws NullPointerException if the specified element is null and this
518 >     *         deque does not permit null elements (optional)
519 >     */
520 >    boolean contains(Object o);
521 >
522 >    /**
523 >     * Returns the number of elements in this deque.
524 >     *
525 >     * @return the number of elements in this deque
526 >     */
527 >    public int size();
528 >
529 >    /**
530 >     * Returns an iterator over the elements in this deque in proper sequence.
531 >     * The elements will be returned in order from first (head) to last (tail).
532 >     *
533 >     * @return an iterator over the elements in this deque in proper sequence
534       */
535      Iterator<E> iterator();
536 +
537 +    /**
538 +     * Returns an iterator over the elements in this deque in reverse
539 +     * sequential order.  The elements will be returned in order from
540 +     * last (tail) to first (head).
541 +     *
542 +     * @return an iterator over the elements in this deque in reverse
543 +     * sequence
544 +     */
545 +    Iterator<E> descendingIterator();
546 +
547   }

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