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*/ |
6 |
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package java.util; |
8 |
+ |
import java.util.*; // for javadoc (till 6280605 is fixed) |
9 |
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|
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/** |
11 |
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* A linear collection that supports element insertion and removal at |
26 |
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* operations cannot fail. |
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* |
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* <p>The twelve methods described above are summarized in the |
29 |
< |
* following table:<p> |
29 |
> |
* following table: |
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* |
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* <p> |
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* <table BORDER CELLPADDING=3 CELLSPACING=1> |
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* <tr> |
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* <td></td> |
38 |
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* <tr> |
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* <td></td> |
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* <td ALIGN=CENTER><em>Throws exception</em></td> |
41 |
< |
* <td ALIGN=CENTER><em>Returns special value</em></td> |
41 |
> |
* <td ALIGN=CENTER><em>Special value</em></td> |
42 |
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* <td ALIGN=CENTER><em>Throws exception</em></td> |
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< |
* <td ALIGN=CENTER><em>Returns special value</em></td> |
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> |
* <td ALIGN=CENTER><em>Special value</em></td> |
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* </tr> |
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* <tr> |
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* <td><b>Insert</b></td> |
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* used as a queue, FIFO (First-In-First-Out) behavior results. Elements are |
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* added at the end of the deque and removed from the beginning. The methods |
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* inherited from the <tt>Queue</tt> interface are precisely equivalent to |
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* <tt>Deque</tt> methods as indicated in the following table:<p> |
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> |
* <tt>Deque</tt> methods as indicated in the following table: |
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* |
74 |
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* <p> |
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* <table BORDER CELLPADDING=3 CELLSPACING=1> |
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* <tr> |
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* <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td> |
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* <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> |
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* </tr> |
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* <tr> |
78 |
– |
* <tr> |
79 |
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* <td>{@link java.util.Queue#offer offer(e)}</td> |
80 |
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* <td>{@link #offerLast offerLast(e)}</td> |
81 |
– |
* </tr> |
82 |
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* <tr> |
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* <td>{@link java.util.Queue#add add(e)}</td> |
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* <td>{@link #addLast addLast(e)}</td> |
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* </tr> |
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* <tr> |
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* <td>{@link java.util.Queue#poll poll()}</td> |
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* <td>{@link #pollFirst pollFirst()}</td> |
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* </tr> |
88 |
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* <tr> |
83 |
> |
* </tr> |
84 |
> |
* <tr> |
85 |
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* <td>{@link java.util.Queue#offer offer(e)}</td> |
86 |
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* <td>{@link #offerLast offerLast(e)}</td> |
87 |
> |
* </tr> |
88 |
> |
* <tr> |
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* <td>{@link java.util.Queue#remove remove()}</td> |
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* <td>{@link #removeFirst removeFirst()}</td> |
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* </tr> |
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* <tr> |
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* <td>{@link java.util.Queue#peek peek()}</td> |
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* <td>{@link #peek peekFirst()}</td> |
95 |
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* </tr> |
96 |
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* <tr> |
91 |
> |
* </tr> |
92 |
> |
* <tr> |
93 |
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* <td>{@link java.util.Queue#poll poll()}</td> |
94 |
> |
* <td>{@link #pollFirst pollFirst()}</td> |
95 |
> |
* </tr> |
96 |
> |
* <tr> |
97 |
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* <td>{@link java.util.Queue#element element()}</td> |
98 |
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* <td>{@link #getFirst getFirst()}</td> |
99 |
< |
* </tr> |
99 |
> |
* </tr> |
100 |
> |
* <tr> |
101 |
> |
* <td>{@link java.util.Queue#peek peek()}</td> |
102 |
> |
* <td>{@link #peek peekFirst()}</td> |
103 |
> |
* </tr> |
104 |
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* </table> |
105 |
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* |
106 |
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* <p>Deques can also be used as LIFO (Last-In-First-Out) stacks. This |
107 |
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* interface should be used in preference to the legacy {@link Stack} class. |
108 |
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* When a deque is used as a stack, elements are pushed and popped from the |
109 |
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* beginning of the deque. Stack methods are precisely equivalent to |
110 |
< |
* <tt>Deque</tt> methods as indicated in the table below:<p> |
110 |
> |
* <tt>Deque</tt> methods as indicated in the table below: |
111 |
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* |
112 |
+ |
* <p> |
113 |
|
* <table BORDER CELLPADDING=3 CELLSPACING=1> |
114 |
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* <tr> |
115 |
|
* <td ALIGN=CENTER> <b>Stack Method</b></td> |
116 |
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* <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> |
117 |
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* </tr> |
118 |
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* <tr> |
116 |
– |
* <tr> |
119 |
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* <td>{@link #push push(e)}</td> |
120 |
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* <td>{@link #addFirst addFirst(e)}</td> |
121 |
< |
* </tr> |
122 |
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* <tr> |
121 |
> |
* </tr> |
122 |
> |
* <tr> |
123 |
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* <td>{@link #pop pop()}</td> |
124 |
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* <td>{@link #removeFirst removeFirst()}</td> |
125 |
< |
* </tr> |
126 |
< |
* <tr> |
125 |
> |
* </tr> |
126 |
> |
* <tr> |
127 |
|
* <td>{@link #peek peek()}</td> |
128 |
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* <td>{@link #peekFirst peekFirst()}</td> |
129 |
< |
* </tr> |
129 |
> |
* </tr> |
130 |
|
* </table> |
131 |
|
* |
132 |
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* <p>Note that the {@link #peek peek} method works equally well when |
135 |
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* |
136 |
|
* <p>This interface provides two methods to remove interior |
137 |
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* elements, {@link #removeFirstOccurrence removeFirstOccurrence} and |
138 |
< |
* {@link #removeLastOccurrence removeLastOccurrence}. Unlike the |
139 |
< |
* {@link List} interface, this interface does not provide support for |
140 |
< |
* indexed access to elements. |
138 |
> |
* {@link #removeLastOccurrence removeLastOccurrence}. |
139 |
> |
* |
140 |
> |
* <p>Unlike the {@link List} interface, this interface does not |
141 |
> |
* provide support for indexed access to elements. |
142 |
|
* |
143 |
|
* <p>While <tt>Deque</tt> implementations are not strictly required |
144 |
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* to prohibit the insertion of null elements, they are strongly |
165 |
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|
166 |
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public interface Deque<E> extends Queue<E> { |
167 |
|
/** |
168 |
+ |
* Inserts the specified element at the front of this deque if it is |
169 |
+ |
* possible to do so immediately without violating capacity restrictions. |
170 |
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* When using a capacity-restricted deque, it is generally preferable to |
171 |
+ |
* use method {@link #offerFirst}. |
172 |
+ |
* |
173 |
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* @param e the element to add |
174 |
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* @throws IllegalStateException if the element cannot be added at this |
175 |
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* time due to capacity restrictions |
176 |
+ |
* @throws ClassCastException if the class of the specified element |
177 |
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* prevents it from being added to this deque |
178 |
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* @throws NullPointerException if the specified element is null and this |
179 |
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* deque does not permit null elements |
180 |
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* @throws IllegalArgumentException if some property of the specified |
181 |
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* element prevents it from being added to this deque |
182 |
+ |
*/ |
183 |
+ |
void addFirst(E e); |
184 |
+ |
|
185 |
+ |
/** |
186 |
+ |
* Inserts the specified element at the end of this deque if it is |
187 |
+ |
* possible to do so immediately without violating capacity restrictions. |
188 |
+ |
* When using a capacity-restricted deque, it is generally preferable to |
189 |
+ |
* use method {@link #offerLast}. |
190 |
+ |
* |
191 |
+ |
* <p>This method is equivalent to {@link #add}. |
192 |
+ |
* |
193 |
+ |
* @param e the element to add |
194 |
+ |
* @throws IllegalStateException if the element cannot be added at this |
195 |
+ |
* time due to capacity restrictions |
196 |
+ |
* @throws ClassCastException if the class of the specified element |
197 |
+ |
* prevents it from being added to this deque |
198 |
+ |
* @throws NullPointerException if the specified element is null and this |
199 |
+ |
* deque does not permit null elements |
200 |
+ |
* @throws IllegalArgumentException if some property of the specified |
201 |
+ |
* element prevents it from being added to this deque |
202 |
+ |
*/ |
203 |
+ |
void addLast(E e); |
204 |
+ |
|
205 |
+ |
/** |
206 |
|
* Inserts the specified element at the front of this deque unless it would |
207 |
|
* violate capacity restrictions. When using a capacity-restricted deque, |
208 |
< |
* this method is generally preferable to method <tt>addFirst</tt>, which |
209 |
< |
* can fail to insert an element only by throwing an exception. |
208 |
> |
* this method is generally preferable to the {@link #addFirst} method, |
209 |
> |
* which can fail to insert an element only by throwing an exception. |
210 |
|
* |
211 |
< |
* @param e the element to insert |
212 |
< |
* @return <tt>true</tt> if it was possible to insert the element, |
213 |
< |
* else <tt>false</tt> |
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> |
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 |
217 |
< |
* deque does not permit null elements |
217 |
> |
* deque does not permit null elements |
218 |
> |
* @throws IllegalArgumentException if some property of the specified |
219 |
> |
* element prevents it from being added to this deque |
220 |
|
*/ |
221 |
|
boolean offerFirst(E e); |
222 |
|
|
223 |
|
/** |
224 |
|
* Inserts the specified element at the end of this deque unless it would |
225 |
|
* violate capacity restrictions. When using a capacity-restricted deque, |
226 |
< |
* this method is generally preferable to method <tt>addLast</tt> which |
227 |
< |
* can fail to insert an element only by throwing an exception. |
226 |
> |
* this method is generally preferable to the {@link #addLast} method, |
227 |
> |
* which can fail to insert an element only by throwing an exception. |
228 |
|
* |
229 |
< |
* @param e the element to insert |
230 |
< |
* @return <tt>true</tt> if it was possible to insert the element, |
231 |
< |
* else <tt>false</tt> |
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> |
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 |
235 |
< |
* deque does not permit null elements |
235 |
> |
* deque does not permit null elements |
236 |
> |
* @throws IllegalArgumentException if some property of the specified |
237 |
> |
* element prevents it from being added to this deque |
238 |
|
*/ |
239 |
|
boolean offerLast(E e); |
240 |
|
|
241 |
|
/** |
242 |
< |
* Inserts the specified element at the front of this deque unless it |
243 |
< |
* would violate capacity restrictions. |
242 |
> |
* Retrieves and removes the first element of this deque. This method |
243 |
> |
* differs from {@link #pollFirst pollFirst} only in that it throws an |
244 |
> |
* exception if this deque is empty. |
245 |
|
* |
246 |
< |
* @param e the element to insert |
247 |
< |
* @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 |
246 |
> |
* @return the head of this deque |
247 |
> |
* @throws NoSuchElementException if this deque is empty |
248 |
|
*/ |
249 |
< |
void addFirst(E e); |
249 |
> |
E removeFirst(); |
250 |
|
|
251 |
|
/** |
252 |
< |
* Inserts the specified element at the end of this deque unless it would |
253 |
< |
* violate capacity restrictions. |
252 |
> |
* Retrieves and removes the last element of this deque. This method |
253 |
> |
* differs from {@link #pollLast pollLast} only in that it throws an |
254 |
> |
* exception if this deque is empty. |
255 |
|
* |
256 |
< |
* @param e the element to insert |
257 |
< |
* @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 |
256 |
> |
* @return the tail of this deque |
257 |
> |
* @throws NoSuchElementException if this deque is empty |
258 |
|
*/ |
259 |
< |
void addLast(E e); |
259 |
> |
E removeLast(); |
260 |
|
|
261 |
|
/** |
262 |
< |
* Retrieves and removes the first element of this deque, or |
263 |
< |
* <tt>null</tt> if this deque is empty. |
262 |
> |
* Retrieves and removes the first element of this deque, |
263 |
> |
* or returns <tt>null</tt> if this deque is empty. |
264 |
|
* |
265 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
221 |
< |
* this deque is empty |
265 |
> |
* @return the head of this deque, or <tt>null</tt> if this deque is empty |
266 |
|
*/ |
267 |
|
E pollFirst(); |
268 |
|
|
269 |
|
/** |
270 |
< |
* Retrieves and removes the last element of this deque, or |
271 |
< |
* <tt>null</tt> if this deque is empty. |
270 |
> |
* Retrieves and removes the last element of this deque, |
271 |
> |
* or returns <tt>null</tt> if this deque is empty. |
272 |
|
* |
273 |
< |
* @return the last element of this deque, or <tt>null</tt> if |
230 |
< |
* this deque is empty |
273 |
> |
* @return the tail of this deque, or <tt>null</tt> if this deque is empty |
274 |
|
*/ |
275 |
|
E pollLast(); |
276 |
|
|
277 |
|
/** |
278 |
< |
* Removes and returns the first element of this deque. This method |
279 |
< |
* differs from the <tt>pollFirst</tt> method only in that it throws an |
280 |
< |
* exception if this deque is empty. |
278 |
> |
* Retrieves, but does not remove, the first element of this deque. |
279 |
> |
* |
280 |
> |
* This method differs from {@link #peekFirst peekFirst} only in that it |
281 |
> |
* throws an exception if this deque is empty. |
282 |
|
* |
283 |
< |
* @return the first element of this deque |
283 |
> |
* @return the head of this deque |
284 |
|
* @throws NoSuchElementException if this deque is empty |
285 |
|
*/ |
286 |
< |
E removeFirst(); |
286 |
> |
E getFirst(); |
287 |
|
|
288 |
|
/** |
289 |
< |
* Retrieves and removes the last element of this deque. This method |
290 |
< |
* differs from the <tt>pollLast</tt> method only in that it throws an |
291 |
< |
* exception if this deque is empty. |
289 |
> |
* Retrieves, but does not remove, the last element of this deque. |
290 |
> |
* This method differs from {@link #peekLast peekLast} only in that it |
291 |
> |
* throws an exception if this deque is empty. |
292 |
|
* |
293 |
< |
* @return the last element of this deque |
293 |
> |
* @return the tail of this deque |
294 |
|
* @throws NoSuchElementException if this deque is empty |
295 |
|
*/ |
296 |
< |
E removeLast(); |
296 |
> |
E getLast(); |
297 |
|
|
298 |
|
/** |
299 |
|
* Retrieves, but does not remove, the first element of this deque, |
300 |
< |
* returning <tt>null</tt> if this deque is empty. |
300 |
> |
* or returns <tt>null</tt> if this deque is empty. |
301 |
|
* |
302 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
259 |
< |
* this deque is empty |
302 |
> |
* @return the head of this deque, or <tt>null</tt> if this deque is empty |
303 |
|
*/ |
304 |
|
E peekFirst(); |
305 |
|
|
306 |
|
/** |
307 |
|
* Retrieves, but does not remove, the last element of this deque, |
308 |
< |
* returning <tt>null</tt> if this deque is empty. |
308 |
> |
* or returns <tt>null</tt> if this deque is empty. |
309 |
|
* |
310 |
< |
* @return the last element of this deque, or <tt>null</tt> if this deque |
268 |
< |
* is empty |
310 |
> |
* @return the tail of this deque, or <tt>null</tt> if this deque is empty |
311 |
|
*/ |
312 |
|
E peekLast(); |
313 |
|
|
314 |
|
/** |
315 |
< |
* Retrieves, but does not remove, the first element of this |
316 |
< |
* deque. This method differs from the <tt>peekFirst</tt> method only |
317 |
< |
* in that it throws an exception if this deque is empty. |
318 |
< |
* |
319 |
< |
* @return the first element of this deque |
320 |
< |
* @throws NoSuchElementException if this deque is empty |
321 |
< |
*/ |
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). |
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 ? e==null : o.equals(e))</tt> |
319 |
> |
* (if such an element exists). |
320 |
> |
* Returns <tt>true</tt> if this deque contained the specified element |
321 |
> |
* (or equivalently, if this deque changed as a result of the call). |
322 |
|
* |
323 |
|
* @param o element to be removed from this deque, if present |
324 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
324 |
> |
* @return <tt>true</tt> if an element was removed as a result of this call |
325 |
> |
* @throws ClassCastException if the class of the specified element |
326 |
> |
* is incompatible with this deque (optional) |
327 |
|
* @throws NullPointerException if the specified element is null and this |
328 |
< |
* deque does not permit null elements |
328 |
> |
* deque does not permit null elements (optional) |
329 |
|
*/ |
330 |
|
boolean removeFirstOccurrence(Object o); |
331 |
|
|
332 |
|
/** |
333 |
< |
* Removes the last occurrence of the specified element in this |
334 |
< |
* deque. If the deque does not contain the element, it is |
335 |
< |
* unchanged. More formally, removes the last element <tt>e</tt> |
336 |
< |
* such that <tt>(o==null ? e==null : o.equals(e))</tt> (if |
337 |
< |
* such an element exists). |
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 ? e==null : o.equals(e))</tt> |
337 |
> |
* (if such an element exists). |
338 |
> |
* Returns <tt>true</tt> 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 <tt>true</tt> if the deque contained the specified element |
342 |
> |
* @return <tt>true</tt> 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) |
345 |
|
* @throws NullPointerException if the specified element is null and this |
346 |
< |
* deque does not permit null elements |
346 |
> |
* deque does not permit null elements (optional) |
347 |
|
*/ |
348 |
|
boolean removeLastOccurrence(Object o); |
349 |
|
|
320 |
– |
|
350 |
|
// *** Queue methods *** |
351 |
|
|
352 |
|
/** |
353 |
|
* Inserts the specified element into the queue represented by this deque |
354 |
< |
* unless it would violate capacity restrictions. In other words, inserts |
355 |
< |
* the specified element at the end of this deque. When using a |
356 |
< |
* capacity-restricted deque, this method is generally preferable to the |
357 |
< |
* {@link #add} method, which can fail to insert an element only by |
358 |
< |
* throwing an exception. |
359 |
< |
* |
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. |
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. |
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 insert |
364 |
< |
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
365 |
< |
* @throws IllegalStateException if it was not possible to insert |
366 |
< |
* the element due to capacity restrictions |
363 |
> |
* @param e the element to add |
364 |
> |
* @return <tt>true</tt> (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 |
368 |
> |
* prevents it from being added to this deque |
369 |
|
* @throws NullPointerException if the specified element is null and this |
370 |
< |
* deque does not permit null elements |
370 |
> |
* deque does not permit null elements |
371 |
> |
* @throws IllegalArgumentException if some property of the specified |
372 |
> |
* element prevents it from being added to this deque |
373 |
|
*/ |
374 |
|
boolean add(E e); |
375 |
|
|
376 |
|
/** |
377 |
< |
* Retrieves and removes the head of the queue represented by |
378 |
< |
* this deque, or <tt>null</tt> if this deque is empty. In other words, |
379 |
< |
* retrieves and removes the first element of this deque, or <tt>null</tt> |
380 |
< |
* if this deque is empty. |
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 |
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. |
384 |
|
* |
385 |
< |
* <p>This method is equivalent to {@link #pollFirst()}. |
385 |
> |
* <p>This method is equivalent to {@link #offerLast}. |
386 |
|
* |
387 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
388 |
< |
* this deque is empty |
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> |
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 |
393 |
> |
* deque does not permit null elements |
394 |
> |
* @throws IllegalArgumentException if some property of the specified |
395 |
> |
* element prevents it from being added to this deque |
396 |
|
*/ |
397 |
< |
E poll(); |
397 |
> |
boolean offer(E e); |
398 |
|
|
399 |
|
/** |
400 |
< |
* Retrieves and removes the head of the queue represented by this deque. |
401 |
< |
* This method differs from the <tt>poll</tt> method only in that it |
402 |
< |
* throws an exception if this deque is empty. |
400 |
> |
* Retrieves and removes the head of the queue represented by this deque |
401 |
> |
* (in other words, the first element of this deque). |
402 |
> |
* This method differs from {@link #poll poll} only in that it throws an |
403 |
> |
* exception if this deque is empty. |
404 |
|
* |
405 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
406 |
|
* |
410 |
|
E remove(); |
411 |
|
|
412 |
|
/** |
413 |
< |
* Retrieves, but does not remove, the head of the queue represented by |
414 |
< |
* this deque, returning <tt>null</tt> if this deque is empty. |
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. |
416 |
|
* |
417 |
< |
* <p>This method is equivalent to {@link #peekFirst()}. |
417 |
> |
* <p>This method is equivalent to {@link #pollFirst()}. |
418 |
|
* |
419 |
< |
* @return the head of the queue represented by this deque, or |
420 |
< |
* <tt>null</tt> if this deque is empty |
419 |
> |
* @return the first element of this deque, or <tt>null</tt> if |
420 |
> |
* this deque is empty |
421 |
|
*/ |
422 |
< |
E peek(); |
422 |
> |
E poll(); |
423 |
|
|
424 |
|
/** |
425 |
|
* Retrieves, but does not remove, the head of the queue represented by |
426 |
< |
* this deque. This method differs from the <tt>peek</tt> method only in |
427 |
< |
* that it throws an exception if this deque is empty. |
426 |
> |
* this deque (in other words, the first element of this deque). |
427 |
> |
* This method differs from {@link #peek peek} only in that it throws an |
428 |
> |
* exception if this deque is empty. |
429 |
|
* |
430 |
|
* <p>This method is equivalent to {@link #getFirst()}. |
431 |
|
* |
434 |
|
*/ |
435 |
|
E element(); |
436 |
|
|
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. |
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 |
446 |
+ |
*/ |
447 |
+ |
E peek(); |
448 |
+ |
|
449 |
|
|
450 |
|
// *** Stack methods *** |
451 |
|
|
452 |
|
/** |
453 |
< |
* Pushes an element onto the stack represented by this deque. In other |
454 |
< |
* words, inserts the element at the front of this deque unless it would |
455 |
< |
* violate capacity restrictions. |
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 |
457 |
> |
* <tt>IllegalStateException</tt> if no space is currently available. |
458 |
|
* |
459 |
|
* <p>This method is equivalent to {@link #addFirst}. |
460 |
|
* |
461 |
|
* @param e the element to push |
462 |
< |
* @throws IllegalStateException if it was not possible to insert |
463 |
< |
* the element due to capacity restrictions |
462 |
> |
* @throws IllegalStateException if the element cannot be added at this |
463 |
> |
* time due to capacity restrictions |
464 |
> |
* @throws ClassCastException if the class of the specified element |
465 |
> |
* prevents it from being added to this deque |
466 |
|
* @throws NullPointerException if the specified element is null and this |
467 |
< |
* deque does not permit null elements |
467 |
> |
* deque does not permit null elements |
468 |
> |
* @throws IllegalArgumentException if some property of the specified |
469 |
> |
* element prevents it from being added to this deque |
470 |
|
*/ |
471 |
|
void push(E e); |
472 |
|
|
477 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
478 |
|
* |
479 |
|
* @return the element at the front of this deque (which is the top |
480 |
< |
* of the stack represented by this deque) |
480 |
> |
* of the stack represented by this deque) |
481 |
|
* @throws NoSuchElementException if this deque is empty |
482 |
|
*/ |
483 |
|
E pop(); |
484 |
|
|
485 |
|
|
486 |
< |
// *** Collection Method *** |
486 |
> |
// *** Collection methods *** |
487 |
> |
|
488 |
> |
/** |
489 |
> |
* Removes the first occurrence of the specified element from this deque. |
490 |
> |
* If the deque does not contain the element, it is unchanged. |
491 |
> |
* More formally, removes the first element <tt>e</tt> such that |
492 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt> |
493 |
> |
* (if such an element exists). |
494 |
> |
* Returns <tt>true</tt> if this deque contained the specified element |
495 |
> |
* (or equivalently, if this deque changed as a result of the call). |
496 |
> |
* |
497 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
498 |
> |
* |
499 |
> |
* @param o element to be removed from this deque, if present |
500 |
> |
* @return <tt>true</tt> 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) |
503 |
> |
* @throws NullPointerException if the specified element is null and this |
504 |
> |
* deque does not permit null elements (optional) |
505 |
> |
*/ |
506 |
> |
boolean remove(Object o); |
507 |
> |
|
508 |
> |
/** |
509 |
> |
* Returns <tt>true</tt> if this deque contains the specified element. |
510 |
> |
* More formally, returns <tt>true</tt> if and only if this deque contains |
511 |
> |
* at least one element <tt>e</tt> such that |
512 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt>. |
513 |
> |
* |
514 |
> |
* @param o element whose presence in this deque is to be tested |
515 |
> |
* @return <tt>true</tt> if this deque contains the specified element |
516 |
> |
* @throws ClassCastException if the type of the specified element |
517 |
> |
* is incompatible with this deque (optional) |
518 |
> |
* @throws NullPointerException if the specified element is null and this |
519 |
> |
* deque does not permit null elements (optional) |
520 |
> |
*/ |
521 |
> |
boolean contains(Object o); |
522 |
> |
|
523 |
> |
/** |
524 |
> |
* Returns the number of elements in this deque. |
525 |
> |
* |
526 |
> |
* @return the number of elements in this deque |
527 |
> |
*/ |
528 |
> |
public int size(); |
529 |
|
|
530 |
|
/** |
531 |
< |
* Returns an iterator over the elements in this deque. The elements |
532 |
< |
* will be ordered from first (head) to last (tail). |
531 |
> |
* Returns an iterator over the elements in this deque in proper sequence. |
532 |
> |
* The elements will be returned in order from first (head) to last (tail). |
533 |
|
* |
534 |
< |
* @return an <tt>Iterator</tt> over the elements in this deque |
534 |
> |
* @return an iterator over the elements in this deque in proper sequence |
535 |
|
*/ |
536 |
|
Iterator<E> iterator(); |
537 |
|
} |