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Comparing jsr166/src/main/java/util/Deque.java (file contents):
Revision 1.19 by jsr166, Sun May 28 23:36:29 2006 UTC vs.
Revision 1.29 by jsr166, Sun Nov 23 18:46:47 2014 UTC

# Line 1 | Line 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
4 > * at http://creativecommons.org/publicdomain/zero/1.0/
5   */
6  
7   package java.util;
# Line 9 | Line 9 | package java.util;
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>
12 > * and is usually pronounced "deck".  Most {@code Deque}
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.
# Line 18 | Line 18 | package java.util;
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
21 > * special value (either {@code null} or {@code false}, 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
24 > * {@code Deque} implementations; in most implementations, insert
25   * operations cannot fail.
26   *
27   * <p>The twelve methods described above are summarized in the
28   * following table:
29   *
30 – * <p>
30   * <table BORDER CELLPADDING=3 CELLSPACING=1>
31 + * <caption>Summary of Deque methods</caption>
32   *  <tr>
33   *    <td></td>
34   *    <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td>
# Line 43 | Line 43 | package java.util;
43   *  </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>
46 > *    <td>{@link Deque#addFirst addFirst(e)}</td>
47 > *    <td>{@link Deque#offerFirst offerFirst(e)}</td>
48 > *    <td>{@link Deque#addLast addLast(e)}</td>
49 > *    <td>{@link Deque#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>
53 > *    <td>{@link Deque#removeFirst removeFirst()}</td>
54 > *    <td>{@link Deque#pollFirst pollFirst()}</td>
55 > *    <td>{@link Deque#removeLast removeLast()}</td>
56 > *    <td>{@link Deque#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>
60 > *    <td>{@link Deque#getFirst getFirst()}</td>
61 > *    <td>{@link Deque#peekFirst peekFirst()}</td>
62 > *    <td>{@link Deque#getLast getLast()}</td>
63 > *    <td>{@link Deque#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   * 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:
70 > * inherited from the {@code Queue} interface are precisely equivalent to
71 > * {@code Deque} methods as indicated in the following table:
72   *
73 – * <p>
73   * <table BORDER CELLPADDING=3 CELLSPACING=1>
74 + * <caption>Comparison of Queue and Deque methods</caption>
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>
76 > *    <td ALIGN=CENTER> <b>{@code Queue} Method</b></td>
77 > *    <td ALIGN=CENTER> <b>Equivalent {@code Deque} Method</b></td>
78   *  </tr>
79   *  <tr>
80   *    <td>{@link java.util.Queue#add add(e)}</td>
# Line 106 | Line 106 | package java.util;
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:
109 > * {@code Deque} methods as indicated in the table below:
110   *
111 – * <p>
111   * <table BORDER CELLPADDING=3 CELLSPACING=1>
112 + * <caption>Comparison of Stack and Deque methods</caption>
113   *  <tr>
114   *    <td ALIGN=CENTER> <b>Stack Method</b></td>
115 < *    <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
115 > *    <td ALIGN=CENTER> <b>Equivalent {@code Deque} Method</b></td>
116   *  </tr>
117   *  <tr>
118   *    <td>{@link #push push(e)}</td>
# Line 139 | Line 139 | package java.util;
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
142 > * <p>While {@code Deque} 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
144 > * encouraged to do so.  Users of any {@code Deque} 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
147 > * {@code null} is used as a special return value by various methods
148   * to indicated that the deque is empty.
149   *
150 < * <p><tt>Deque</tt> implementations generally do not define
151 < * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt>
150 > * <p>{@code Deque} implementations generally do not define
151 > * element-based versions of the {@code equals} and {@code hashCode}
152   * methods, but instead inherit the identity-based versions from class
153 < * <tt>Object</tt>.
153 > * {@code Object}.
154   *
155   * <p>This interface is a member of the <a
156   * href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections
# Line 161 | Line 161 | package java.util;
161   * @since  1.6
162   * @param <E> the type of elements held in this collection
163   */
164 –
164   public interface Deque<E> extends Queue<E> {
165      /**
166       * Inserts the specified element at the front of this deque if it is
167 <     * possible to do so immediately without violating capacity restrictions.
168 <     * When using a capacity-restricted deque, it is generally preferable to
169 <     * use method {@link #offerFirst}.
167 >     * possible to do so immediately without violating capacity restrictions,
168 >     * throwing an {@code IllegalStateException} if no space is currently
169 >     * available.  When using a capacity-restricted deque, it is generally
170 >     * preferable to use method {@link #offerFirst}.
171       *
172       * @param e the element to add
173       * @throws IllegalStateException if the element cannot be added at this
# Line 183 | Line 183 | public interface Deque<E> extends Queue<
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}.
186 >     * possible to do so immediately without violating capacity restrictions,
187 >     * throwing an {@code IllegalStateException} if no space is currently
188 >     * available.  When using a capacity-restricted deque, it is generally
189 >     * preferable to use method {@link #offerLast}.
190       *
191       * <p>This method is equivalent to {@link #add}.
192       *
# Line 208 | Line 209 | public interface Deque<E> extends Queue<
209       * which can fail to insert an element only by throwing an exception.
210       *
211       * @param e the element to add
212 <     * @return <tt>true</tt> if the element was added to this deque, else
213 <     *         <tt>false</tt>
212 >     * @return {@code true} if the element was added to this deque, else
213 >     *         {@code false}
214       * @throws ClassCastException if the class of the specified element
215       *         prevents it from being added to this deque
216       * @throws NullPointerException if the specified element is null and this
# Line 226 | Line 227 | public interface Deque<E> extends Queue<
227       * which can fail to insert an element only by throwing an exception.
228       *
229       * @param e the element to add
230 <     * @return <tt>true</tt> if the element was added to this deque, else
231 <     *         <tt>false</tt>
230 >     * @return {@code true} if the element was added to this deque, else
231 >     *         {@code false}
232       * @throws ClassCastException if the class of the specified element
233       *         prevents it from being added to this deque
234       * @throws NullPointerException if the specified element is null and this
# Line 259 | Line 260 | public interface Deque<E> extends Queue<
260  
261      /**
262       * Retrieves and removes the first element of this deque,
263 <     * or returns <tt>null</tt> if this deque is empty.
263 >     * or returns {@code null} if this deque is empty.
264       *
265 <     * @return the head of this deque, or <tt>null</tt> if this deque is empty
265 >     * @return the head of this deque, or {@code null} if this deque is empty
266       */
267      E pollFirst();
268  
269      /**
270       * Retrieves and removes the last element of this deque,
271 <     * or returns <tt>null</tt> if this deque is empty.
271 >     * or returns {@code null} if this deque is empty.
272       *
273 <     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
273 >     * @return the tail of this deque, or {@code null} if this deque is empty
274       */
275      E pollLast();
276  
# Line 296 | Line 297 | public interface Deque<E> extends Queue<
297  
298      /**
299       * Retrieves, but does not remove, the first element of this deque,
300 <     * or returns <tt>null</tt> if this deque is empty.
300 >     * or returns {@code null} if this deque is empty.
301       *
302 <     * @return the head of this deque, or <tt>null</tt> if this deque is empty
302 >     * @return the head of this deque, or {@code null} if this deque is empty
303       */
304      E peekFirst();
305  
306      /**
307       * Retrieves, but does not remove, the last element of this deque,
308 <     * or returns <tt>null</tt> if this deque is empty.
308 >     * or returns {@code null} if this deque is empty.
309       *
310 <     * @return the tail of this deque, or <tt>null</tt> if this deque is empty
310 >     * @return the tail of this deque, or {@code null} if this deque is empty
311       */
312      E peekLast();
313  
314      /**
315       * Removes the first occurrence of the specified element from this deque.
316       * If the deque does not contain the element, it is unchanged.
317 <     * More formally, removes the first element <tt>e</tt> such that
318 <     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
319 <     * (if such an element exists).
319 <     * Returns <tt>true</tt> if this deque contained the specified element
317 >     * More formally, removes the first element {@code e} such that
318 >     * {@code Objects.equals(o, e)} (if such an element exists).
319 >     * Returns {@code true} 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 an element was removed as a result of this call
323 >     * @return {@code true} 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 (optional)
325 >     *         is incompatible with this deque
326 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
327 >     * @throws NullPointerException if the specified element is null
328 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
329       */
330      boolean removeFirstOccurrence(Object o);
331  
332      /**
333       * Removes the last occurrence of the specified element from this deque.
334       * If the deque does not contain the element, it is unchanged.
335 <     * More formally, removes the last element <tt>e</tt> such that
336 <     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
337 <     * (if such an element exists).
337 <     * Returns <tt>true</tt> if this deque contained the specified element
335 >     * More formally, removes the last element {@code e} such that
336 >     * {@code Objects.equals(o, e)} (if such an element exists).
337 >     * Returns {@code true} 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 an element was removed as a result of this call
341 >     * @return {@code true} 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 (optional)
343 >     *         is incompatible with this deque
344 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
345 >     * @throws NullPointerException if the specified element is null
346 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
347       */
348      boolean removeLastOccurrence(Object o);
349  
# Line 352 | Line 353 | public interface Deque<E> extends Queue<
353       * Inserts the specified element into the queue represented by this deque
354       * (in other words, at the tail of this deque) if it is possible to do so
355       * immediately without violating capacity restrictions, returning
356 <     * <tt>true</tt> upon success and throwing an
357 <     * <tt>IllegalStateException</tt> if no space is currently available.
356 >     * {@code true} upon success and throwing an
357 >     * {@code IllegalStateException} if no space is currently available.
358       * When using a capacity-restricted deque, it is generally preferable to
359       * use {@link #offer(Object) offer}.
360       *
361       * <p>This method is equivalent to {@link #addLast}.
362       *
363       * @param e the element to add
364 <     * @return <tt>true</tt> (as specified by {@link Collection#add})
364 >     * @return {@code true} (as specified by {@link Collection#add})
365       * @throws IllegalStateException if the element cannot be added at this
366       *         time due to capacity restrictions
367       * @throws ClassCastException if the class of the specified element
# Line 376 | Line 377 | public interface Deque<E> extends Queue<
377       * Inserts the specified element into the queue represented by this deque
378       * (in other words, at the tail of this deque) if it is possible to do so
379       * immediately without violating capacity restrictions, returning
380 <     * <tt>true</tt> upon success and <tt>false</tt> if no space is currently
380 >     * {@code true} upon success and {@code false} if no space is currently
381       * available.  When using a capacity-restricted deque, this method is
382       * generally preferable to the {@link #add} method, which can fail to
383       * insert an element only by throwing an exception.
# Line 384 | Line 385 | public interface Deque<E> extends Queue<
385       * <p>This method is equivalent to {@link #offerLast}.
386       *
387       * @param e the element to add
388 <     * @return <tt>true</tt> if the element was added to this deque, else
389 <     *         <tt>false</tt>
388 >     * @return {@code true} if the element was added to this deque, else
389 >     *         {@code false}
390       * @throws ClassCastException if the class of the specified element
391       *         prevents it from being added to this deque
392       * @throws NullPointerException if the specified element is null and this
# Line 411 | Line 412 | public interface Deque<E> extends Queue<
412      /**
413       * Retrieves and removes the head of the queue represented by this deque
414       * (in other words, the first element of this deque), or returns
415 <     * <tt>null</tt> if this deque is empty.
415 >     * {@code null} if this deque is empty.
416       *
417       * <p>This method is equivalent to {@link #pollFirst()}.
418       *
419 <     * @return the first element of this deque, or <tt>null</tt> if
419 >     * @return the first element of this deque, or {@code null} if
420       *         this deque is empty
421       */
422      E poll();
# Line 436 | Line 437 | public interface Deque<E> extends Queue<
437      /**
438       * Retrieves, but does not remove, the head of the queue represented by
439       * this deque (in other words, the first element of this deque), or
440 <     * returns <tt>null</tt> if this deque is empty.
440 >     * returns {@code null} if this deque is empty.
441       *
442       * <p>This method is equivalent to {@link #peekFirst()}.
443       *
444       * @return the head of the queue represented by this deque, or
445 <     *         <tt>null</tt> if this deque is empty
445 >     *         {@code null} if this deque is empty
446       */
447      E peek();
448  
# Line 451 | Line 452 | public interface Deque<E> extends Queue<
452      /**
453       * Pushes an element onto the stack represented by this deque (in other
454       * words, at the head of this deque) if it is possible to do so
455 <     * immediately without violating capacity restrictions, returning
456 <     * <tt>true</tt> upon success and throwing an
456 <     * <tt>IllegalStateException</tt> if no space is currently available.
455 >     * immediately without violating capacity restrictions, throwing an
456 >     * {@code IllegalStateException} if no space is currently available.
457       *
458       * <p>This method is equivalent to {@link #addFirst}.
459       *
# Line 487 | Line 487 | public interface Deque<E> extends Queue<
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 <     * <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
490 >     * More formally, removes the first element {@code e} such that
491 >     * {@code Objects.equals(o, e)} (if such an element exists).
492 >     * Returns {@code true} if this deque contained the specified element
493       * (or equivalently, if this deque changed as a result of the call).
494       *
495 <     * <p>This method is equivalent to {@link #removeFirstOccurrence}.
495 >     * <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
496       *
497       * @param o element to be removed from this deque, if present
498 <     * @return <tt>true</tt> if an element was removed as a result of this call
498 >     * @return {@code true} if an element was removed as a result of this call
499       * @throws ClassCastException if the class of the specified element
500 <     *         is incompatible with this deque (optional)
501 <     * @throws NullPointerException if the specified element is null and this
502 <     *         deque does not permit null elements (optional)
500 >     *         is incompatible with this deque
501 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
502 >     * @throws NullPointerException if the specified element is null
503 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
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>.
508 >     * Returns {@code true} if this deque contains the specified element.
509 >     * More formally, returns {@code true} if and only if this deque contains
510 >     * at least one element {@code e} such that {@code Objects.equals(o, e)}.
511       *
512       * @param o element whose presence in this deque is to be tested
513 <     * @return <tt>true</tt> if this deque contains the specified element
514 <     * @throws ClassCastException if the type of the specified element
515 <     *         is incompatible with this deque (optional)
516 <     * @throws NullPointerException if the specified element is null and this
517 <     *         deque does not permit null elements (optional)
513 >     * @return {@code true} if this deque contains the specified element
514 >     * @throws ClassCastException if the class of the specified element
515 >     *         is incompatible with this deque
516 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
517 >     * @throws NullPointerException if the specified element is null
518 >     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
519       */
520      boolean contains(Object o);
521  

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