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> |
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 #addFirst(Object) addFirst(e)}</td> |
47 |
> |
* <td>{@link #offerFirst(Object) offerFirst(e)}</td> |
48 |
> |
* <td>{@link #addLast(Object) addLast(e)}</td> |
49 |
> |
* <td>{@link #offerLast(Object) 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 #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> |
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 |
|
* |
70 |
|
* inherited from the {@code Queue} interface are precisely equivalent to |
71 |
|
* {@code Deque} methods as indicated in the following table: |
72 |
|
* |
74 |
– |
* <p> |
73 |
|
* <table BORDER CELLPADDING=3 CELLSPACING=1> |
74 |
|
* <caption>Comparison of Queue and Deque methods</caption> |
75 |
|
* <tr> |
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> |
81 |
< |
* <td>{@link #addLast addLast(e)}</td> |
80 |
> |
* <td>{@link #add(Object) add(e)}</td> |
81 |
> |
* <td>{@link #addLast(Object) addLast(e)}</td> |
82 |
|
* </tr> |
83 |
|
* <tr> |
84 |
< |
* <td>{@link java.util.Queue#offer offer(e)}</td> |
85 |
< |
* <td>{@link #offerLast offerLast(e)}</td> |
84 |
> |
* <td>{@link #offer(Object) offer(e)}</td> |
85 |
> |
* <td>{@link #offerLast(Object) offerLast(e)}</td> |
86 |
|
* </tr> |
87 |
|
* <tr> |
88 |
< |
* <td>{@link java.util.Queue#remove remove()}</td> |
89 |
< |
* <td>{@link #removeFirst removeFirst()}</td> |
88 |
> |
* <td>{@link #remove() remove()}</td> |
89 |
> |
* <td>{@link #removeFirst() removeFirst()}</td> |
90 |
|
* </tr> |
91 |
|
* <tr> |
92 |
< |
* <td>{@link java.util.Queue#poll poll()}</td> |
93 |
< |
* <td>{@link #pollFirst pollFirst()}</td> |
92 |
> |
* <td>{@link #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> |
96 |
> |
* <td>{@link #element() element()}</td> |
97 |
> |
* <td>{@link #getFirst() getFirst()}</td> |
98 |
|
* </tr> |
99 |
|
* <tr> |
100 |
< |
* <td>{@link java.util.Queue#peek peek()}</td> |
101 |
< |
* <td>{@link #peek peekFirst()}</td> |
100 |
> |
* <td>{@link #peek() peek()}</td> |
101 |
> |
* <td>{@link #peekFirst() peekFirst()}</td> |
102 |
|
* </tr> |
103 |
|
* </table> |
104 |
|
* |
108 |
|
* beginning of the deque. Stack methods are precisely equivalent to |
109 |
|
* {@code Deque} methods as indicated in the table below: |
110 |
|
* |
113 |
– |
* <p> |
111 |
|
* <table BORDER CELLPADDING=3 CELLSPACING=1> |
112 |
|
* <caption>Comparison of Stack and Deque methods</caption> |
113 |
|
* <tr> |
115 |
|
* <td ALIGN=CENTER> <b>Equivalent {@code Deque} Method</b></td> |
116 |
|
* </tr> |
117 |
|
* <tr> |
118 |
< |
* <td>{@link #push push(e)}</td> |
119 |
< |
* <td>{@link #addFirst addFirst(e)}</td> |
118 |
> |
* <td>{@link #push(Object) push(e)}</td> |
119 |
> |
* <td>{@link #addFirst(Object) addFirst(e)}</td> |
120 |
|
* </tr> |
121 |
|
* <tr> |
122 |
< |
* <td>{@link #pop pop()}</td> |
123 |
< |
* <td>{@link #removeFirst removeFirst()}</td> |
122 |
> |
* <td>{@link #pop() pop()}</td> |
123 |
> |
* <td>{@link #removeFirst() removeFirst()}</td> |
124 |
|
* </tr> |
125 |
|
* <tr> |
126 |
< |
* <td>{@link #peek peek()}</td> |
127 |
< |
* <td>{@link #peekFirst peekFirst()}</td> |
126 |
> |
* <td>{@link #peek() peek()}</td> |
127 |
> |
* <td>{@link #peekFirst() peekFirst()}</td> |
128 |
|
* </tr> |
129 |
|
* </table> |
130 |
|
* |
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 |
|
* {@code null} is used as a special return value by various methods |
148 |
< |
* to indicated that the deque is empty. |
148 |
> |
* to indicate that the deque is empty. |
149 |
|
* |
150 |
|
* <p>{@code Deque} implementations generally do not define |
151 |
|
* element-based versions of the {@code equals} and {@code hashCode} |
159 |
|
* @author Doug Lea |
160 |
|
* @author Josh Bloch |
161 |
|
* @since 1.6 |
162 |
< |
* @param <E> the type of elements held in this collection |
162 |
> |
* @param <E> the type of elements held in this deque |
163 |
|
*/ |
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 |
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 |
|
* |
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 {@code e} such that |
318 |
< |
* <tt>(o==null ? e==null : o.equals(e))</tt> |
320 |
< |
* (if such an element exists). |
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 {@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) |
325 |
> |
* is incompatible with this deque |
326 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
327 |
|
* @throws NullPointerException if the specified element is null and this |
328 |
< |
* deque does not permit null elements (optional) |
328 |
> |
* deque does not permit null elements |
329 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
330 |
|
*/ |
331 |
|
boolean removeFirstOccurrence(Object o); |
332 |
|
|
334 |
|
* Removes the last occurrence of the specified element from this deque. |
335 |
|
* If the deque does not contain the element, it is unchanged. |
336 |
|
* More formally, removes the last element {@code e} such that |
337 |
< |
* <tt>(o==null ? e==null : o.equals(e))</tt> |
338 |
< |
* (if such an element exists). |
337 |
> |
* {@code Objects.equals(o, e)} (if such an element exists). |
338 |
|
* Returns {@code true} if this deque contained the specified element |
339 |
|
* (or equivalently, if this deque changed as a result of the call). |
340 |
|
* |
341 |
|
* @param o element to be removed from this deque, if present |
342 |
|
* @return {@code true} if an element was removed as a result of this call |
343 |
|
* @throws ClassCastException if the class of the specified element |
344 |
< |
* is incompatible with this deque (optional) |
344 |
> |
* is incompatible with this deque |
345 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
346 |
|
* @throws NullPointerException if the specified element is null and this |
347 |
< |
* deque does not permit null elements (optional) |
347 |
> |
* deque does not permit null elements |
348 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
349 |
|
*/ |
350 |
|
boolean removeLastOccurrence(Object o); |
351 |
|
|
401 |
|
/** |
402 |
|
* Retrieves and removes the head of the queue represented by this deque |
403 |
|
* (in other words, the first element of this deque). |
404 |
< |
* This method differs from {@link #poll poll} only in that it throws an |
405 |
< |
* exception if this deque is empty. |
404 |
> |
* This method differs from {@link #poll() poll()} only in that it |
405 |
> |
* throws an exception if this deque is empty. |
406 |
|
* |
407 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
408 |
|
* |
454 |
|
/** |
455 |
|
* Pushes an element onto the stack represented by this deque (in other |
456 |
|
* words, at the head of this deque) if it is possible to do so |
457 |
< |
* immediately without violating capacity restrictions, returning |
457 |
< |
* {@code true} upon success and throwing an |
457 |
> |
* immediately without violating capacity restrictions, throwing an |
458 |
|
* {@code IllegalStateException} if no space is currently available. |
459 |
|
* |
460 |
|
* <p>This method is equivalent to {@link #addFirst}. |
490 |
|
* Removes the first occurrence of the specified element from this deque. |
491 |
|
* If the deque does not contain the element, it is unchanged. |
492 |
|
* More formally, removes the first element {@code e} such that |
493 |
< |
* <tt>(o==null ? e==null : o.equals(e))</tt> |
494 |
< |
* (if such an element exists). |
493 |
> |
* {@code Objects.equals(o, e)} (if such an element exists). |
494 |
|
* Returns {@code true} if this deque contained the specified element |
495 |
|
* (or equivalently, if this deque changed as a result of the call). |
496 |
|
* |
499 |
|
* @param o element to be removed from this deque, if present |
500 |
|
* @return {@code true} if an element was removed as a result of this call |
501 |
|
* @throws ClassCastException if the class of the specified element |
502 |
< |
* is incompatible with this deque (optional) |
502 |
> |
* is incompatible with this deque |
503 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
504 |
|
* @throws NullPointerException if the specified element is null and this |
505 |
< |
* deque does not permit null elements (optional) |
505 |
> |
* deque does not permit null elements |
506 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
507 |
|
*/ |
508 |
|
boolean remove(Object o); |
509 |
|
|
510 |
|
/** |
511 |
|
* Returns {@code true} if this deque contains the specified element. |
512 |
|
* More formally, returns {@code true} if and only if this deque contains |
513 |
< |
* at least one element {@code e} such that |
513 |
< |
* <tt>(o==null ? e==null : o.equals(e))</tt>. |
513 |
> |
* at least one element {@code e} such that {@code Objects.equals(o, e)}. |
514 |
|
* |
515 |
|
* @param o element whose presence in this deque is to be tested |
516 |
|
* @return {@code true} if this deque contains the specified element |
517 |
< |
* @throws ClassCastException if the type of the specified element |
518 |
< |
* is incompatible with this deque (optional) |
517 |
> |
* @throws ClassCastException if the class of the specified element |
518 |
> |
* is incompatible with this deque |
519 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
520 |
|
* @throws NullPointerException if the specified element is null and this |
521 |
< |
* deque does not permit null elements (optional) |
521 |
> |
* deque does not permit null elements |
522 |
> |
* (<a href="{@docRoot}/../api/java/util/Collection.html#optional-restrictions">optional</a>) |
523 |
|
*/ |
524 |
|
boolean contains(Object o); |
525 |
|
|
528 |
|
* |
529 |
|
* @return the number of elements in this deque |
530 |
|
*/ |
531 |
< |
public int size(); |
531 |
> |
int size(); |
532 |
|
|
533 |
|
/** |
534 |
|
* Returns an iterator over the elements in this deque in proper sequence. |