[cvs] / jsr166 / src / main / java / util / Deque.java Repository:
ViewVC logotype

Annotation of /jsr166/src/main/java/util/Deque.java

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.18 - (view) (download)

1 : dl 1.1 /*
2 :     * Written by Doug Lea and Josh Bloch with assistance from members of
3 :     * JCP JSR-166 Expert Group and released to the public domain, as explained
4 :     * at http://creativecommons.org/licenses/publicdomain
5 :     */
6 :    
7 :     package java.util;
8 :    
9 :     /**
10 :     * A linear collection that supports element insertion and removal at
11 :     * both ends. The name <i>deque</i> is short for "double ended queue"
12 :     * and is usually pronounced "deck". Most <tt>Deque</tt>
13 :     * implementations place no fixed limits on the number of elements
14 :     * they may contain, but this interface supports capacity-restricted
15 :     * deques as well as those with no fixed size limit.
16 :     *
17 :     * <p>This interface defines methods to access the elements at both
18 :     * ends of the deque. Methods are provided to insert, remove, and
19 :     * examine the element. Each of these methods exists in two forms:
20 :     * one throws an exception if the operation fails, the other returns a
21 :     * special value (either <tt>null</tt> or <tt>false</tt>, depending on
22 :     * the operation). The latter form of the insert operation is
23 :     * designed specifically for use with capacity-restricted
24 :     * <tt>Deque</tt> implementations; in most implementations, insert
25 :     * operations cannot fail.
26 :     *
27 : dl 1.3 * <p>The twelve methods described above are summarized in the
28 : jsr166 1.5 * following table:
29 : dl 1.3 *
30 : jsr166 1.7 * <p>
31 :     * <table BORDER CELLPADDING=3 CELLSPACING=1>
32 : dl 1.1 * <tr>
33 :     * <td></td>
34 :     * <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td>
35 :     * <td ALIGN=CENTER COLSPAN = 2> <b>Last Element (Tail)</b></td>
36 :     * </tr>
37 :     * <tr>
38 :     * <td></td>
39 :     * <td ALIGN=CENTER><em>Throws exception</em></td>
40 : jsr166 1.8 * <td ALIGN=CENTER><em>Special value</em></td>
41 : dl 1.1 * <td ALIGN=CENTER><em>Throws exception</em></td>
42 : jsr166 1.8 * <td ALIGN=CENTER><em>Special value</em></td>
43 : dl 1.1 * </tr>
44 :     * <tr>
45 :     * <td><b>Insert</b></td>
46 :     * <td>{@link #addFirst addFirst(e)}</td>
47 :     * <td>{@link #offerFirst offerFirst(e)}</td>
48 :     * <td>{@link #addLast addLast(e)}</td>
49 :     * <td>{@link #offerLast offerLast(e)}</td>
50 :     * </tr>
51 :     * <tr>
52 :     * <td><b>Remove</b></td>
53 :     * <td>{@link #removeFirst removeFirst()}</td>
54 :     * <td>{@link #pollFirst pollFirst()}</td>
55 :     * <td>{@link #removeLast removeLast()}</td>
56 :     * <td>{@link #pollLast pollLast()}</td>
57 :     * </tr>
58 :     * <tr>
59 :     * <td><b>Examine</b></td>
60 :     * <td>{@link #getFirst getFirst()}</td>
61 :     * <td>{@link #peekFirst peekFirst()}</td>
62 :     * <td>{@link #getLast getLast()}</td>
63 :     * <td>{@link #peekLast peekLast()}</td>
64 :     * </tr>
65 :     * </table>
66 :     *
67 :     * <p>This interface extends the {@link Queue} interface. When a deque is
68 :     * used as a queue, FIFO (First-In-First-Out) behavior results. Elements are
69 : dl 1.4 * added at the end of the deque and removed from the beginning. The methods
70 : dl 1.1 * inherited from the <tt>Queue</tt> interface are precisely equivalent to
71 : jsr166 1.5 * <tt>Deque</tt> methods as indicated in the following table:
72 : dl 1.1 *
73 : jsr166 1.7 * <p>
74 :     * <table BORDER CELLPADDING=3 CELLSPACING=1>
75 : dl 1.1 * <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>
80 : jsr166 1.8 * <td>{@link java.util.Queue#add add(e)}</td>
81 :     * <td>{@link #addLast addLast(e)}</td>
82 :     * </tr>
83 :     * <tr>
84 : dl 1.1 * <td>{@link java.util.Queue#offer offer(e)}</td>
85 :     * <td>{@link #offerLast offerLast(e)}</td>
86 : jsr166 1.5 * </tr>
87 :     * <tr>
88 : jsr166 1.8 * <td>{@link java.util.Queue#remove remove()}</td>
89 :     * <td>{@link #removeFirst removeFirst()}</td>
90 : jsr166 1.5 * </tr>
91 :     * <tr>
92 : dl 1.1 * <td>{@link java.util.Queue#poll poll()}</td>
93 :     * <td>{@link #pollFirst pollFirst()}</td>
94 : jsr166 1.5 * </tr>
95 :     * <tr>
96 : jsr166 1.8 * <td>{@link java.util.Queue#element element()}</td>
97 :     * <td>{@link #getFirst getFirst()}</td>
98 : jsr166 1.5 * </tr>
99 :     * <tr>
100 : dl 1.1 * <td>{@link java.util.Queue#peek peek()}</td>
101 :     * <td>{@link #peek peekFirst()}</td>
102 : jsr166 1.5 * </tr>
103 : dl 1.1 * </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 : dl 1.3 * When a deque is used as a stack, elements are pushed and popped from the
108 : dl 1.1 * beginning of the deque. Stack methods are precisely equivalent to
109 : jsr166 1.5 * <tt>Deque</tt> methods as indicated in the table below:
110 : dl 1.1 *
111 : jsr166 1.7 * <p>
112 :     * <table BORDER CELLPADDING=3 CELLSPACING=1>
113 : dl 1.1 * <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>
118 :     * <td>{@link #push push(e)}</td>
119 :     * <td>{@link #addFirst addFirst(e)}</td>
120 : jsr166 1.5 * </tr>
121 :     * <tr>
122 : dl 1.1 * <td>{@link #pop pop()}</td>
123 :     * <td>{@link #removeFirst removeFirst()}</td>
124 : jsr166 1.5 * </tr>
125 :     * <tr>
126 : dl 1.1 * <td>{@link #peek peek()}</td>
127 :     * <td>{@link #peekFirst peekFirst()}</td>
128 : jsr166 1.5 * </tr>
129 : dl 1.1 * </table>
130 :     *
131 :     * <p>Note that the {@link #peek peek} method works equally well when
132 :     * a deque is used as a queue or a stack; in either case, elements are
133 :     * drawn from the beginning of the deque.
134 :     *
135 : dl 1.2 * <p>This interface provides two methods to remove interior
136 : dl 1.1 * elements, {@link #removeFirstOccurrence removeFirstOccurrence} and
137 : jsr166 1.8 * {@link #removeLastOccurrence removeLastOccurrence}.
138 :     *
139 :     * <p>Unlike the {@link List} interface, this interface does not
140 :     * provide support for indexed access to elements.
141 : dl 1.1 *
142 :     * <p>While <tt>Deque</tt> implementations are not strictly required
143 :     * to prohibit the insertion of null elements, they are strongly
144 :     * encouraged to do so. Users of any <tt>Deque</tt> implementations
145 :     * that do allow null elements are strongly encouraged <i>not</i> to
146 :     * take advantage of the ability to insert nulls. This is so because
147 :     * <tt>null</tt> is used as a special return value by various methods
148 :     * to indicated that the deque is empty.
149 : dl 1.3 *
150 : dl 1.1 * <p><tt>Deque</tt> implementations generally do not define
151 :     * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt>
152 :     * methods, but instead inherit the identity-based versions from class
153 :     * <tt>Object</tt>.
154 :     *
155 :     * <p>This interface is a member of the <a
156 :     * href="{@docRoot}/../guide/collections/index.html"> Java Collections
157 :     * Framework</a>.
158 :     *
159 :     * @author Doug Lea
160 :     * @author Josh Bloch
161 :     * @since 1.6
162 :     * @param <E> the type of elements held in this collection
163 :     */
164 :    
165 :     public interface Deque<E> extends Queue<E> {
166 :     /**
167 : jsr166 1.8 * 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 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
176 :     * prevents it from being added to this deque
177 : jsr166 1.8 * @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 : jsr166 1.13 * Inserts the specified element at the end of this deque if it is
186 : jsr166 1.8 * 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 : jsr166 1.14 * <p>This method is equivalent to {@link #add}.
191 :     *
192 : jsr166 1.8 * @param e the element to add
193 :     * @throws IllegalStateException if the element cannot be added at this
194 :     * time due to capacity restrictions
195 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
196 :     * prevents it from being added to this deque
197 : jsr166 1.8 * @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 : dl 1.3 * Inserts the specified element at the front of this deque unless it would
206 : dl 1.1 * violate capacity restrictions. When using a capacity-restricted deque,
207 : jsr166 1.8 * this method is generally preferable to the {@link #addFirst} method,
208 :     * which can fail to insert an element only by throwing an exception.
209 : dl 1.1 *
210 : jsr166 1.8 * @param e the element to add
211 : jsr166 1.11 * @return <tt>true</tt> if the element was added to this deque, else
212 :     * <tt>false</tt>
213 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
214 :     * prevents it from being added to this deque
215 : dl 1.3 * @throws NullPointerException if the specified element is null and this
216 : jsr166 1.8 * 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 : dl 1.1 */
220 :     boolean offerFirst(E e);
221 :    
222 :     /**
223 : dl 1.4 * Inserts the specified element at the end of this deque unless it would
224 : dl 1.1 * violate capacity restrictions. When using a capacity-restricted deque,
225 : jsr166 1.8 * this method is generally preferable to the {@link #addLast} method,
226 :     * which can fail to insert an element only by throwing an exception.
227 : dl 1.1 *
228 : jsr166 1.8 * @param e the element to add
229 : jsr166 1.11 * @return <tt>true</tt> if the element was added to this deque, else
230 :     * <tt>false</tt>
231 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
232 :     * prevents it from being added to this deque
233 : dl 1.3 * @throws NullPointerException if the specified element is null and this
234 : jsr166 1.8 * 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 : dl 1.1 */
238 :     boolean offerLast(E e);
239 :    
240 :     /**
241 : jsr166 1.8 * Retrieves and removes the first element of this deque. This method
242 : jsr166 1.15 * differs from {@link #pollFirst pollFirst} only in that it throws an
243 :     * exception if this deque is empty.
244 : dl 1.1 *
245 : jsr166 1.8 * @return the head of this deque
246 :     * @throws NoSuchElementException if this deque is empty
247 : dl 1.1 */
248 : jsr166 1.8 E removeFirst();
249 : dl 1.1
250 :     /**
251 : jsr166 1.8 * Retrieves and removes the last element of this deque. This method
252 : jsr166 1.15 * differs from {@link #pollLast pollLast} only in that it throws an
253 :     * exception if this deque is empty.
254 : dl 1.1 *
255 : jsr166 1.8 * @return the tail of this deque
256 :     * @throws NoSuchElementException if this deque is empty
257 : dl 1.1 */
258 : jsr166 1.8 E removeLast();
259 : dl 1.1
260 :     /**
261 : jsr166 1.8 * Retrieves and removes the first element of this deque,
262 :     * or returns <tt>null</tt> if this deque is empty.
263 : dl 1.1 *
264 : jsr166 1.8 * @return the head of this deque, or <tt>null</tt> if this deque is empty
265 : dl 1.1 */
266 :     E pollFirst();
267 :    
268 :     /**
269 : jsr166 1.8 * Retrieves and removes the last element of this deque,
270 :     * or returns <tt>null</tt> if this deque is empty.
271 : dl 1.1 *
272 : jsr166 1.8 * @return the tail of this deque, or <tt>null</tt> if this deque is empty
273 : dl 1.1 */
274 :     E pollLast();
275 :    
276 :     /**
277 : jsr166 1.8 * Retrieves, but does not remove, the first element of this deque.
278 : jsr166 1.16 *
279 : jsr166 1.15 * This method differs from {@link #peekFirst peekFirst} only in that it
280 :     * throws an exception if this deque is empty.
281 : dl 1.1 *
282 : jsr166 1.8 * @return the head of this deque
283 : dl 1.1 * @throws NoSuchElementException if this deque is empty
284 :     */
285 : jsr166 1.8 E getFirst();
286 : dl 1.1
287 :     /**
288 : jsr166 1.8 * Retrieves, but does not remove, the last element of this deque.
289 : jsr166 1.15 * This method differs from {@link #peekLast peekLast} only in that it
290 :     * throws an exception if this deque is empty.
291 : dl 1.1 *
292 : jsr166 1.8 * @return the tail of this deque
293 : dl 1.1 * @throws NoSuchElementException if this deque is empty
294 :     */
295 : jsr166 1.8 E getLast();
296 : dl 1.1
297 :     /**
298 :     * Retrieves, but does not remove, the first element of this deque,
299 : jsr166 1.8 * or returns <tt>null</tt> if this deque is empty.
300 : dl 1.1 *
301 : jsr166 1.8 * @return the head of this deque, or <tt>null</tt> if this deque is empty
302 : dl 1.1 */
303 :     E peekFirst();
304 :    
305 :     /**
306 :     * Retrieves, but does not remove, the last element of this deque,
307 : jsr166 1.8 * or returns <tt>null</tt> if this deque is empty.
308 : dl 1.1 *
309 : jsr166 1.8 * @return the tail of this deque, or <tt>null</tt> if this deque is empty
310 : dl 1.1 */
311 :     E peekLast();
312 :    
313 :     /**
314 : jsr166 1.8 * 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 : jsr166 1.9 * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
318 :     * (if such an element exists).
319 : jsr166 1.12 * 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 : dl 1.1 *
322 : dl 1.3 * @param o element to be removed from this deque, if present
323 : jsr166 1.8 * @return <tt>true</tt> if an element was removed as a result of this call
324 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
325 :     * is incompatible with this deque (optional)
326 : dl 1.4 * @throws NullPointerException if the specified element is null and this
327 : jsr166 1.8 * deque does not permit null elements (optional)
328 : dl 1.1 */
329 : dl 1.3 boolean removeFirstOccurrence(Object o);
330 : dl 1.1
331 :     /**
332 : jsr166 1.8 * 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 : jsr166 1.9 * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
336 :     * (if such an element exists).
337 : jsr166 1.12 * 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 : dl 1.1 *
340 : dl 1.3 * @param o element to be removed from this deque, if present
341 : jsr166 1.8 * @return <tt>true</tt> if an element was removed as a result of this call
342 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
343 :     * is incompatible with this deque (optional)
344 : dl 1.4 * @throws NullPointerException if the specified element is null and this
345 : jsr166 1.8 * deque does not permit null elements (optional)
346 : dl 1.1 */
347 : dl 1.3 boolean removeLastOccurrence(Object o);
348 : dl 1.1
349 : jsr166 1.8 // *** Queue methods ***
350 : dl 1.1
351 : jsr166 1.8 /**
352 :     * Inserts the specified element into the queue represented by 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 : jsr166 1.14 * <p>This method is equivalent to {@link #addLast}.
361 : jsr166 1.8 *
362 :     * @param e the element to add
363 : jsr166 1.15 * @return <tt>true</tt> (as specified by {@link Collection#add})
364 : jsr166 1.8 * @throws IllegalStateException if the element cannot be added at this
365 :     * time due to capacity restrictions
366 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
367 :     * prevents it from being added to this deque
368 : jsr166 1.8 * @throws NullPointerException if the specified element is null and this
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 : dl 1.1
375 :     /**
376 :     * Inserts the specified element into the queue represented by this deque
377 : jsr166 1.8 * (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 : dl 1.1 *
384 :     * <p>This method is equivalent to {@link #offerLast}.
385 :     *
386 : jsr166 1.8 * @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 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
390 :     * prevents it from being added to this deque
391 : dl 1.3 * @throws NullPointerException if the specified element is null and this
392 : jsr166 1.8 * 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 : dl 1.1 */
396 :     boolean offer(E e);
397 :    
398 :     /**
399 : jsr166 1.8 * Retrieves and removes the head of the queue represented by this deque
400 :     * (in other words, the first element of this deque).
401 : jsr166 1.15 * This method differs from {@link #poll poll} only in that it throws an
402 : jsr166 1.8 * exception if this deque is empty.
403 : dl 1.1 *
404 : jsr166 1.8 * <p>This method is equivalent to {@link #removeFirst()}.
405 : dl 1.1 *
406 : jsr166 1.8 * @return the head of the queue represented by this deque
407 :     * @throws NoSuchElementException if this deque is empty
408 : dl 1.1 */
409 : jsr166 1.8 E remove();
410 : dl 1.1
411 :     /**
412 : jsr166 1.8 * 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 : dl 1.1 *
416 :     * <p>This method is equivalent to {@link #pollFirst()}.
417 :     *
418 :     * @return the first element of this deque, or <tt>null</tt> if
419 : jsr166 1.8 * this deque is empty
420 : dl 1.1 */
421 :     E poll();
422 :    
423 :     /**
424 : jsr166 1.8 * Retrieves, but does not remove, the head of the queue represented by
425 :     * this deque (in other words, the first element of this deque).
426 : jsr166 1.15 * This method differs from {@link #peek peek} only in that it throws an
427 : jsr166 1.8 * exception if this deque is empty.
428 : dl 1.1 *
429 : jsr166 1.8 * <p>This method is equivalent to {@link #getFirst()}.
430 : dl 1.1 *
431 :     * @return the head of the queue represented by this deque
432 :     * @throws NoSuchElementException if this deque is empty
433 :     */
434 : jsr166 1.8 E element();
435 : dl 1.1
436 :     /**
437 :     * Retrieves, but does not remove, the head of the queue represented by
438 : jsr166 1.8 * this deque (in other words, the first element of this deque), or
439 :     * returns <tt>null</tt> if this deque is empty.
440 : dl 1.1 *
441 : dl 1.3 * <p>This method is equivalent to {@link #peekFirst()}.
442 : dl 1.1 *
443 :     * @return the head of the queue represented by this deque, or
444 : jsr166 1.8 * <tt>null</tt> if this deque is empty
445 : dl 1.1 */
446 :     E peek();
447 :    
448 :    
449 :     // *** Stack methods ***
450 :    
451 :     /**
452 : jsr166 1.8 * 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 : dl 1.1 *
458 :     * <p>This method is equivalent to {@link #addFirst}.
459 :     *
460 : dl 1.3 * @param e the element to push
461 : jsr166 1.8 * @throws IllegalStateException if the element cannot be added at this
462 :     * time due to capacity restrictions
463 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
464 :     * prevents it from being added to this deque
465 : dl 1.3 * @throws NullPointerException if the specified element is null and this
466 : jsr166 1.8 * 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 : dl 1.1 */
470 :     void push(E e);
471 :    
472 :     /**
473 :     * Pops an element from the stack represented by this deque. In other
474 : dl 1.2 * words, removes and returns the first element of this deque.
475 : dl 1.1 *
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 : jsr166 1.8 * of the stack represented by this deque)
480 : dl 1.1 * @throws NoSuchElementException if this deque is empty
481 :     */
482 :     E pop();
483 :    
484 :    
485 : jsr166 1.8 // *** Collection methods ***
486 :    
487 :     /**
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 : jsr166 1.9 * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
492 :     * (if such an element exists).
493 : jsr166 1.12 * 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 : jsr166 1.8 *
496 :     * <p>This method is equivalent to {@link #removeFirstOccurrence}.
497 :     *
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 : jsr166 1.9 * @throws ClassCastException if the class of the specified element
501 :     * is incompatible with this deque (optional)
502 : jsr166 1.8 * @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 : jsr166 1.9 * 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 : jsr166 1.8 *
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 : dl 1.1
529 :     /**
530 : jsr166 1.10 * 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 : dl 1.3 *
533 : jsr166 1.10 * @return an iterator over the elements in this deque in proper sequence
534 : dl 1.1 */
535 :     Iterator<E> iterator();
536 : dl 1.17
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 : dl 1.1 }

Doug Lea
ViewVC Help
Powered by ViewVC 1.0.8