| 37 |
|
* <tr> |
| 38 |
|
* <td></td> |
| 39 |
|
* <td ALIGN=CENTER><em>Throws exception</em></td> |
| 40 |
< |
* <td ALIGN=CENTER><em>Returns special value</em></td> |
| 40 |
> |
* <td ALIGN=CENTER><em>Special value</em></td> |
| 41 |
|
* <td ALIGN=CENTER><em>Throws exception</em></td> |
| 42 |
< |
* <td ALIGN=CENTER><em>Returns special value</em></td> |
| 42 |
> |
* <td ALIGN=CENTER><em>Special value</em></td> |
| 43 |
|
* </tr> |
| 44 |
|
* <tr> |
| 45 |
|
* <td><b>Insert</b></td> |
| 77 |
|
* <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> |
| 78 |
|
* </tr> |
| 79 |
|
* <tr> |
| 80 |
– |
* <td>{@link java.util.Queue#offer offer(e)}</td> |
| 81 |
– |
* <td>{@link #offerLast offerLast(e)}</td> |
| 82 |
– |
* </tr> |
| 83 |
– |
* <tr> |
| 80 |
|
* <td>{@link java.util.Queue#add add(e)}</td> |
| 81 |
|
* <td>{@link #addLast addLast(e)}</td> |
| 82 |
|
* </tr> |
| 83 |
|
* <tr> |
| 84 |
< |
* <td>{@link java.util.Queue#poll poll()}</td> |
| 85 |
< |
* <td>{@link #pollFirst pollFirst()}</td> |
| 84 |
> |
* <td>{@link java.util.Queue#offer offer(e)}</td> |
| 85 |
> |
* <td>{@link #offerLast offerLast(e)}</td> |
| 86 |
|
* </tr> |
| 87 |
|
* <tr> |
| 88 |
|
* <td>{@link java.util.Queue#remove remove()}</td> |
| 89 |
|
* <td>{@link #removeFirst removeFirst()}</td> |
| 90 |
|
* </tr> |
| 91 |
|
* <tr> |
| 92 |
< |
* <td>{@link java.util.Queue#peek peek()}</td> |
| 93 |
< |
* <td>{@link #peek peekFirst()}</td> |
| 92 |
> |
* <td>{@link java.util.Queue#poll poll()}</td> |
| 93 |
> |
* <td>{@link #pollFirst pollFirst()}</td> |
| 94 |
|
* </tr> |
| 95 |
|
* <tr> |
| 96 |
|
* <td>{@link java.util.Queue#element element()}</td> |
| 97 |
|
* <td>{@link #getFirst getFirst()}</td> |
| 98 |
|
* </tr> |
| 99 |
+ |
* <tr> |
| 100 |
+ |
* <td>{@link java.util.Queue#peek peek()}</td> |
| 101 |
+ |
* <td>{@link #peek peekFirst()}</td> |
| 102 |
+ |
* </tr> |
| 103 |
|
* </table> |
| 104 |
|
* |
| 105 |
|
* <p>Deques can also be used as LIFO (Last-In-First-Out) stacks. This |
| 134 |
|
* |
| 135 |
|
* <p>This interface provides two methods to remove interior |
| 136 |
|
* elements, {@link #removeFirstOccurrence removeFirstOccurrence} and |
| 137 |
< |
* {@link #removeLastOccurrence removeLastOccurrence}. Unlike the |
| 138 |
< |
* {@link List} interface, this interface does not provide support for |
| 139 |
< |
* indexed access to elements. |
| 137 |
> |
* {@link #removeLastOccurrence removeLastOccurrence}. |
| 138 |
> |
* |
| 139 |
> |
* <p>Unlike the {@link List} interface, this interface does not |
| 140 |
> |
* provide support for indexed access to elements. |
| 141 |
|
* |
| 142 |
|
* <p>While <tt>Deque</tt> implementations are not strictly required |
| 143 |
|
* to prohibit the insertion of null elements, they are strongly |
| 164 |
|
|
| 165 |
|
public interface Deque<E> extends Queue<E> { |
| 166 |
|
/** |
| 167 |
+ |
* Inserts the specified element at the front of this deque if it is |
| 168 |
+ |
* possible to do so immediately without violating capacity restrictions. |
| 169 |
+ |
* When using a capacity-restricted deque, it is generally preferable to |
| 170 |
+ |
* use method {@link #offerFirst}. |
| 171 |
+ |
* |
| 172 |
+ |
* @param e the element to add |
| 173 |
+ |
* @throws IllegalStateException if the element cannot be added at this |
| 174 |
+ |
* time due to capacity restrictions |
| 175 |
+ |
* @throws NullPointerException if the specified element is null and this |
| 176 |
+ |
* deque does not permit null elements |
| 177 |
+ |
* @throws ClassCastException if the class of the specified element |
| 178 |
+ |
* prevents it from being added to this deque |
| 179 |
+ |
* @throws IllegalArgumentException if some property of the specified |
| 180 |
+ |
* element prevents it from being added to this deque |
| 181 |
+ |
*/ |
| 182 |
+ |
void addFirst(E e); |
| 183 |
+ |
|
| 184 |
+ |
/** |
| 185 |
+ |
* Inserts the specified element at the end of this deque if it is |
| 186 |
+ |
* possible to do so immediately without violating capacity restrictions. |
| 187 |
+ |
* When using a capacity-restricted deque, it is generally preferable to |
| 188 |
+ |
* use method {@link #offerLast}. |
| 189 |
+ |
* |
| 190 |
+ |
* @param e the element to add |
| 191 |
+ |
* @throws IllegalStateException if the element cannot be added at this |
| 192 |
+ |
* time due to capacity restrictions |
| 193 |
+ |
* @throws NullPointerException if the specified element is null and this |
| 194 |
+ |
* deque does not permit null elements |
| 195 |
+ |
* @throws ClassCastException if the class of the specified element |
| 196 |
+ |
* prevents it from being added to this deque |
| 197 |
+ |
* @throws IllegalArgumentException if some property of the specified |
| 198 |
+ |
* element prevents it from being added to this deque |
| 199 |
+ |
*/ |
| 200 |
+ |
void addLast(E e); |
| 201 |
+ |
|
| 202 |
+ |
/** |
| 203 |
|
* Inserts the specified element at the front of this deque unless it would |
| 204 |
|
* violate capacity restrictions. When using a capacity-restricted deque, |
| 205 |
< |
* this method is generally preferable to method <tt>addFirst</tt>, which |
| 206 |
< |
* can fail to insert an element only by throwing an exception. |
| 205 |
> |
* this method is generally preferable to the {@link #addFirst} method, |
| 206 |
> |
* which can fail to insert an element only by throwing an exception. |
| 207 |
|
* |
| 208 |
< |
* @param e the element to insert |
| 208 |
> |
* @param e the element to add |
| 209 |
|
* @return <tt>true</tt> if it was possible to insert the element, |
| 210 |
< |
* else <tt>false</tt> |
| 210 |
> |
* else <tt>false</tt> |
| 211 |
|
* @throws NullPointerException if the specified element is null and this |
| 212 |
< |
* deque does not permit null elements |
| 212 |
> |
* deque does not permit null elements |
| 213 |
> |
* @throws ClassCastException if the class of the specified element |
| 214 |
> |
* prevents it from being added to this deque |
| 215 |
> |
* @throws IllegalArgumentException if some property of the specified |
| 216 |
> |
* element prevents it from being added to this deque |
| 217 |
|
*/ |
| 218 |
|
boolean offerFirst(E e); |
| 219 |
|
|
| 220 |
|
/** |
| 221 |
|
* Inserts the specified element at the end of this deque unless it would |
| 222 |
|
* violate capacity restrictions. When using a capacity-restricted deque, |
| 223 |
< |
* this method is generally preferable to method <tt>addLast</tt> which |
| 224 |
< |
* can fail to insert an element only by throwing an exception. |
| 223 |
> |
* this method is generally preferable to the {@link #addLast} method, |
| 224 |
> |
* which can fail to insert an element only by throwing an exception. |
| 225 |
|
* |
| 226 |
< |
* @param e the element to insert |
| 226 |
> |
* @param e the element to add |
| 227 |
|
* @return <tt>true</tt> if it was possible to insert the element, |
| 228 |
< |
* else <tt>false</tt> |
| 228 |
> |
* else <tt>false</tt> |
| 229 |
|
* @throws NullPointerException if the specified element is null and this |
| 230 |
< |
* deque does not permit null elements |
| 230 |
> |
* deque does not permit null elements |
| 231 |
> |
* @throws ClassCastException if the class of the specified element |
| 232 |
> |
* prevents it from being added to this deque |
| 233 |
> |
* @throws IllegalArgumentException if some property of the specified |
| 234 |
> |
* element prevents it from being added to this deque |
| 235 |
|
*/ |
| 236 |
|
boolean offerLast(E e); |
| 237 |
|
|
| 238 |
|
/** |
| 239 |
< |
* Inserts the specified element at the front of this deque unless it |
| 240 |
< |
* would violate capacity restrictions. |
| 239 |
> |
* Retrieves and removes the first element of this deque. This method |
| 240 |
> |
* differs from {@link #pollFirst} only in that it throws an exception |
| 241 |
> |
* if this deque is empty. |
| 242 |
|
* |
| 243 |
< |
* @param e the element to insert |
| 244 |
< |
* @throws IllegalStateException if it was not possible to insert |
| 199 |
< |
* the element due to capacity restrictions |
| 200 |
< |
* @throws NullPointerException if the specified element is null and this |
| 201 |
< |
* deque does not permit null elements |
| 243 |
> |
* @return the head of this deque |
| 244 |
> |
* @throws NoSuchElementException if this deque is empty |
| 245 |
|
*/ |
| 246 |
< |
void addFirst(E e); |
| 246 |
> |
E removeFirst(); |
| 247 |
|
|
| 248 |
|
/** |
| 249 |
< |
* Inserts the specified element at the end of this deque unless it would |
| 250 |
< |
* violate capacity restrictions. |
| 249 |
> |
* Retrieves and removes the last element of this deque. This method |
| 250 |
> |
* differs from {@link #pollLast} only in that it throws an exception if |
| 251 |
> |
* this deque is empty. |
| 252 |
|
* |
| 253 |
< |
* @param e the element to insert |
| 254 |
< |
* @throws IllegalStateException if it was not possible to insert |
| 211 |
< |
* the element due to capacity restrictions |
| 212 |
< |
* @throws NullPointerException if the specified element is null and this |
| 213 |
< |
* deque does not permit null elements |
| 253 |
> |
* @return the tail of this deque |
| 254 |
> |
* @throws NoSuchElementException if this deque is empty |
| 255 |
|
*/ |
| 256 |
< |
void addLast(E e); |
| 256 |
> |
E removeLast(); |
| 257 |
|
|
| 258 |
|
/** |
| 259 |
< |
* Retrieves and removes the first element of this deque, or |
| 260 |
< |
* <tt>null</tt> if this deque is empty. |
| 259 |
> |
* Retrieves and removes the first element of this deque, |
| 260 |
> |
* or returns <tt>null</tt> if this deque is empty. |
| 261 |
|
* |
| 262 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
| 222 |
< |
* this deque is empty |
| 262 |
> |
* @return the head of this deque, or <tt>null</tt> if this deque is empty |
| 263 |
|
*/ |
| 264 |
|
E pollFirst(); |
| 265 |
|
|
| 266 |
|
/** |
| 267 |
< |
* Retrieves and removes the last element of this deque, or |
| 268 |
< |
* <tt>null</tt> if this deque is empty. |
| 267 |
> |
* Retrieves and removes the last element of this deque, |
| 268 |
> |
* or returns <tt>null</tt> if this deque is empty. |
| 269 |
|
* |
| 270 |
< |
* @return the last element of this deque, or <tt>null</tt> if |
| 231 |
< |
* this deque is empty |
| 270 |
> |
* @return the tail of this deque, or <tt>null</tt> if this deque is empty |
| 271 |
|
*/ |
| 272 |
|
E pollLast(); |
| 273 |
|
|
| 274 |
|
/** |
| 275 |
< |
* Retrieves and removes the first element of this deque. This method |
| 276 |
< |
* differs from the {@link #pollFirst} method only in that it throws an |
| 275 |
> |
* Retrieves, but does not remove, the first element of this deque. |
| 276 |
> |
* This method differs from {@link #peekFirst} only in that it throws an |
| 277 |
|
* exception if this deque is empty. |
| 278 |
|
* |
| 279 |
< |
* @return the first element of this deque |
| 279 |
> |
* @return the head of this deque |
| 280 |
|
* @throws NoSuchElementException if this deque is empty |
| 281 |
|
*/ |
| 282 |
< |
E removeFirst(); |
| 282 |
> |
E getFirst(); |
| 283 |
|
|
| 284 |
|
/** |
| 285 |
< |
* Retrieves and removes the last element of this deque. This method |
| 286 |
< |
* differs from the {@link #pollLast} method only in that it throws an |
| 285 |
> |
* Retrieves, but does not remove, the last element of this deque. |
| 286 |
> |
* This method differs from {@link #peekLast} only in that it throws an |
| 287 |
|
* exception if this deque is empty. |
| 288 |
|
* |
| 289 |
< |
* @return the last element of this deque |
| 289 |
> |
* @return the tail of this deque |
| 290 |
|
* @throws NoSuchElementException if this deque is empty |
| 291 |
|
*/ |
| 292 |
< |
E removeLast(); |
| 292 |
> |
E getLast(); |
| 293 |
|
|
| 294 |
|
/** |
| 295 |
|
* Retrieves, but does not remove, the first element of this deque, |
| 296 |
< |
* returning <tt>null</tt> if this deque is empty. |
| 296 |
> |
* or returns <tt>null</tt> if this deque is empty. |
| 297 |
|
* |
| 298 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
| 260 |
< |
* this deque is empty |
| 298 |
> |
* @return the head of this deque, or <tt>null</tt> if this deque is empty |
| 299 |
|
*/ |
| 300 |
|
E peekFirst(); |
| 301 |
|
|
| 302 |
|
/** |
| 303 |
|
* Retrieves, but does not remove, the last element of this deque, |
| 304 |
< |
* returning <tt>null</tt> if this deque is empty. |
| 304 |
> |
* or returns <tt>null</tt> if this deque is empty. |
| 305 |
|
* |
| 306 |
< |
* @return the last element of this deque, or <tt>null</tt> if this deque |
| 269 |
< |
* is empty |
| 306 |
> |
* @return the tail of this deque, or <tt>null</tt> if this deque is empty |
| 307 |
|
*/ |
| 308 |
|
E peekLast(); |
| 309 |
|
|
| 310 |
|
/** |
| 311 |
< |
* Retrieves, but does not remove, the first element of this |
| 312 |
< |
* deque. This method differs from the {@link #peekFirst} method only |
| 313 |
< |
* in that it throws an exception if this deque is empty. |
| 314 |
< |
* |
| 315 |
< |
* @return the first element of this deque |
| 316 |
< |
* @throws NoSuchElementException if this deque is empty |
| 280 |
< |
*/ |
| 281 |
< |
E getFirst(); |
| 282 |
< |
|
| 283 |
< |
/** |
| 284 |
< |
* Retrieves, but does not remove, the last element of this |
| 285 |
< |
* deque. This method differs from the {@link #peekLast} method only |
| 286 |
< |
* in that it throws an exception if this deque is empty. |
| 287 |
< |
* |
| 288 |
< |
* @return the last element of this deque |
| 289 |
< |
* @throws NoSuchElementException if this deque is empty |
| 290 |
< |
*/ |
| 291 |
< |
E getLast(); |
| 292 |
< |
|
| 293 |
< |
/** |
| 294 |
< |
* Removes the first occurrence of the specified element in this |
| 295 |
< |
* deque. If the deque does not contain the element, it is |
| 296 |
< |
* unchanged. More formally, removes the first element <tt>e</tt> |
| 297 |
< |
* such that <tt>(o==null ? e==null : o.equals(e))</tt> (if |
| 298 |
< |
* such an element exists). |
| 311 |
> |
* Removes the first occurrence of the specified element from this deque. |
| 312 |
> |
* If the deque does not contain the element, it is unchanged. |
| 313 |
> |
* More formally, removes the first element <tt>e</tt> such that |
| 314 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt> (if such an element exists). |
| 315 |
> |
* Returns true if this deque contained the specified element (or |
| 316 |
> |
* equivalently, if this deque changed as a result of the call). |
| 317 |
|
* |
| 318 |
|
* @param o element to be removed from this deque, if present |
| 319 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
| 319 |
> |
* @return <tt>true</tt> if an element was removed as a result of this call |
| 320 |
|
* @throws NullPointerException if the specified element is null and this |
| 321 |
< |
* deque does not permit null elements |
| 321 |
> |
* deque does not permit null elements (optional) |
| 322 |
> |
* @throws ClassCastException if the class of the specified element |
| 323 |
> |
* is incompatible with this collection (optional) |
| 324 |
|
*/ |
| 325 |
|
boolean removeFirstOccurrence(Object o); |
| 326 |
|
|
| 327 |
|
/** |
| 328 |
< |
* Removes the last occurrence of the specified element in this |
| 329 |
< |
* deque. If the deque does not contain the element, it is |
| 330 |
< |
* unchanged. More formally, removes the last element <tt>e</tt> |
| 331 |
< |
* such that <tt>(o==null ? e==null : o.equals(e))</tt> (if |
| 332 |
< |
* such an element exists). |
| 328 |
> |
* Removes the last occurrence of the specified element from this deque. |
| 329 |
> |
* If the deque does not contain the element, it is unchanged. |
| 330 |
> |
* More formally, removes the last element <tt>e</tt> such that |
| 331 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt> (if such an element exists). |
| 332 |
> |
* Returns true if this deque contained the specified element (or |
| 333 |
> |
* equivalently, if this deque changed as a result of the call). |
| 334 |
|
* |
| 335 |
|
* @param o element to be removed from this deque, if present |
| 336 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
| 336 |
> |
* @return <tt>true</tt> if an element was removed as a result of this call |
| 337 |
|
* @throws NullPointerException if the specified element is null and this |
| 338 |
< |
* deque does not permit null elements |
| 338 |
> |
* deque does not permit null elements (optional) |
| 339 |
> |
* @throws ClassCastException if the class of the specified element |
| 340 |
> |
* is incompatible with this collection (optional) |
| 341 |
|
*/ |
| 342 |
|
boolean removeLastOccurrence(Object o); |
| 343 |
|
|
| 321 |
– |
|
| 344 |
|
// *** Queue methods *** |
| 345 |
|
|
| 346 |
|
/** |
| 347 |
|
* Inserts the specified element into the queue represented by this deque |
| 348 |
< |
* unless it would violate capacity restrictions. In other words, inserts |
| 349 |
< |
* the specified element at the end of this deque. When using a |
| 350 |
< |
* capacity-restricted deque, this method is generally preferable to the |
| 351 |
< |
* {@link #add} method, which can fail to insert an element only by |
| 352 |
< |
* throwing an exception. |
| 353 |
< |
* |
| 332 |
< |
* <p>This method is equivalent to {@link #offerLast}. |
| 333 |
< |
* |
| 334 |
< |
* @param e the element to insert |
| 335 |
< |
* @return <tt>true</tt> if it was possible to insert the element, |
| 336 |
< |
* else <tt>false</tt> |
| 337 |
< |
* @throws NullPointerException if the specified element is null and this |
| 338 |
< |
* deque does not permit null elements |
| 339 |
< |
*/ |
| 340 |
< |
boolean offer(E e); |
| 341 |
< |
|
| 342 |
< |
/** |
| 343 |
< |
* Inserts the specified element into the queue represented by this |
| 344 |
< |
* deque unless it would violate capacity restrictions. In other words, |
| 345 |
< |
* inserts the specified element as the last element of this deque. |
| 348 |
> |
* (in other words, at the tail of this deque) if it is possible to do so |
| 349 |
> |
* immediately without violating capacity restrictions, returning |
| 350 |
> |
* <tt>true</tt> upon success and throwing an |
| 351 |
> |
* <tt>IllegalStateException</tt> if no space is currently available. |
| 352 |
> |
* When using a capacity-restricted deque, it is generally preferable to |
| 353 |
> |
* use {@link #offer(Object) offer}. |
| 354 |
|
* |
| 355 |
< |
* <p>This method is equivalent to {@link #addLast}. |
| 355 |
> |
* <p>This method is equivalent to {@link #addLast(Object) addLast}. |
| 356 |
|
* |
| 357 |
< |
* @param e the element to insert |
| 357 |
> |
* @param e the element to add |
| 358 |
|
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
| 359 |
< |
* @throws IllegalStateException if it was not possible to insert |
| 360 |
< |
* the element due to capacity restrictions |
| 359 |
> |
* @throws IllegalStateException if the element cannot be added at this |
| 360 |
> |
* time due to capacity restrictions |
| 361 |
|
* @throws NullPointerException if the specified element is null and this |
| 362 |
< |
* deque does not permit null elements |
| 362 |
> |
* deque does not permit null elements |
| 363 |
> |
* @throws ClassCastException if the class of the specified element |
| 364 |
> |
* prevents it from being added to this deque |
| 365 |
> |
* @throws IllegalArgumentException if some property of the specified |
| 366 |
> |
* element prevents it from being added to this deque |
| 367 |
|
*/ |
| 368 |
|
boolean add(E e); |
| 369 |
|
|
| 370 |
|
/** |
| 371 |
< |
* Retrieves and removes the head of the queue represented by |
| 372 |
< |
* this deque, or <tt>null</tt> if this deque is empty. In other words, |
| 373 |
< |
* retrieves and removes the first element of this deque, or <tt>null</tt> |
| 374 |
< |
* if this deque is empty. |
| 371 |
> |
* Inserts the specified element into the queue represented by this deque |
| 372 |
> |
* (in other words, at the tail of this deque) if it is possible to do so |
| 373 |
> |
* immediately without violating capacity restrictions, returning |
| 374 |
> |
* <tt>true</tt> upon success and <tt>false</tt> if no space is currently |
| 375 |
> |
* available. When using a capacity-restricted deque, this method is |
| 376 |
> |
* generally preferable to the {@link #add} method, which can fail to |
| 377 |
> |
* insert an element only by throwing an exception. |
| 378 |
|
* |
| 379 |
< |
* <p>This method is equivalent to {@link #pollFirst()}. |
| 379 |
> |
* <p>This method is equivalent to {@link #offerLast}. |
| 380 |
|
* |
| 381 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
| 382 |
< |
* this deque is empty |
| 381 |
> |
* @param e the element to add |
| 382 |
> |
* @return <tt>true</tt> if the element was added to this deque, else |
| 383 |
> |
* <tt>false</tt> |
| 384 |
> |
* @throws NullPointerException if the specified element is null and this |
| 385 |
> |
* deque does not permit null elements |
| 386 |
> |
* @throws ClassCastException if the class of the specified element |
| 387 |
> |
* prevents it from being added to this deque |
| 388 |
> |
* @throws IllegalArgumentException if some property of the specified |
| 389 |
> |
* element prevents it from being added to this deque |
| 390 |
|
*/ |
| 391 |
< |
E poll(); |
| 391 |
> |
boolean offer(E e); |
| 392 |
|
|
| 393 |
|
/** |
| 394 |
< |
* Retrieves and removes the head of the queue represented by this deque. |
| 395 |
< |
* This method differs from the {@link #poll} method only in that it |
| 396 |
< |
* throws an exception if this deque is empty. |
| 394 |
> |
* Retrieves and removes the head of the queue represented by this deque |
| 395 |
> |
* (in other words, the first element of this deque). |
| 396 |
> |
* This method differs from {@link #poll} only in that it throws an |
| 397 |
> |
* exception if this deque is empty. |
| 398 |
|
* |
| 399 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
| 400 |
|
* |
| 404 |
|
E remove(); |
| 405 |
|
|
| 406 |
|
/** |
| 407 |
< |
* Retrieves, but does not remove, the head of the queue represented by |
| 408 |
< |
* this deque, returning <tt>null</tt> if this deque is empty. |
| 407 |
> |
* Retrieves and removes the head of the queue represented by this deque |
| 408 |
> |
* (in other words, the first element of this deque), or returns |
| 409 |
> |
* <tt>null</tt> if this deque is empty. |
| 410 |
|
* |
| 411 |
< |
* <p>This method is equivalent to {@link #peekFirst()}. |
| 411 |
> |
* <p>This method is equivalent to {@link #pollFirst()}. |
| 412 |
|
* |
| 413 |
< |
* @return the head of the queue represented by this deque, or |
| 414 |
< |
* <tt>null</tt> if this deque is empty |
| 413 |
> |
* @return the first element of this deque, or <tt>null</tt> if |
| 414 |
> |
* this deque is empty |
| 415 |
|
*/ |
| 416 |
< |
E peek(); |
| 416 |
> |
E poll(); |
| 417 |
|
|
| 418 |
|
/** |
| 419 |
|
* Retrieves, but does not remove, the head of the queue represented by |
| 420 |
< |
* this deque. This method differs from the {@link #peek} method only in |
| 421 |
< |
* that it throws an exception if this deque is empty. |
| 420 |
> |
* this deque (in other words, the first element of this deque). |
| 421 |
> |
* This method differs from {@link #peek} only in that it throws an |
| 422 |
> |
* exception if this deque is empty. |
| 423 |
|
* |
| 424 |
|
* <p>This method is equivalent to {@link #getFirst()}. |
| 425 |
|
* |
| 428 |
|
*/ |
| 429 |
|
E element(); |
| 430 |
|
|
| 431 |
+ |
/** |
| 432 |
+ |
* Retrieves, but does not remove, the head of the queue represented by |
| 433 |
+ |
* this deque (in other words, the first element of this deque), or |
| 434 |
+ |
* returns <tt>null</tt> if this deque is empty. |
| 435 |
+ |
* |
| 436 |
+ |
* <p>This method is equivalent to {@link #peekFirst()}. |
| 437 |
+ |
* |
| 438 |
+ |
* @return the head of the queue represented by this deque, or |
| 439 |
+ |
* <tt>null</tt> if this deque is empty |
| 440 |
+ |
*/ |
| 441 |
+ |
E peek(); |
| 442 |
+ |
|
| 443 |
|
|
| 444 |
|
// *** Stack methods *** |
| 445 |
|
|
| 446 |
|
/** |
| 447 |
< |
* Pushes an element onto the stack represented by this deque. In other |
| 448 |
< |
* words, inserts the element at the front of this deque unless it would |
| 449 |
< |
* violate capacity restrictions. |
| 447 |
> |
* Pushes an element onto the stack represented by this deque (in other |
| 448 |
> |
* words, at the head of this deque) if it is possible to do so |
| 449 |
> |
* immediately without violating capacity restrictions, returning |
| 450 |
> |
* <tt>true</tt> upon success and throwing an |
| 451 |
> |
* <tt>IllegalStateException</tt> if no space is currently available. |
| 452 |
|
* |
| 453 |
|
* <p>This method is equivalent to {@link #addFirst}. |
| 454 |
|
* |
| 455 |
|
* @param e the element to push |
| 456 |
< |
* @throws IllegalStateException if it was not possible to insert |
| 457 |
< |
* the element due to capacity restrictions |
| 456 |
> |
* @throws IllegalStateException if the element cannot be added at this |
| 457 |
> |
* time due to capacity restrictions |
| 458 |
|
* @throws NullPointerException if the specified element is null and this |
| 459 |
< |
* deque does not permit null elements |
| 459 |
> |
* deque does not permit null elements |
| 460 |
> |
* @throws ClassCastException if the class of the specified element |
| 461 |
> |
* prevents it from being added to this deque |
| 462 |
> |
* @throws IllegalArgumentException if some property of the specified |
| 463 |
> |
* element prevents it from being added to this deque |
| 464 |
|
*/ |
| 465 |
|
void push(E e); |
| 466 |
|
|
| 471 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
| 472 |
|
* |
| 473 |
|
* @return the element at the front of this deque (which is the top |
| 474 |
< |
* of the stack represented by this deque) |
| 474 |
> |
* of the stack represented by this deque) |
| 475 |
|
* @throws NoSuchElementException if this deque is empty |
| 476 |
|
*/ |
| 477 |
|
E pop(); |
| 478 |
|
|
| 479 |
|
|
| 480 |
< |
// *** Collection Method *** |
| 480 |
> |
// *** Collection methods *** |
| 481 |
> |
|
| 482 |
> |
/** |
| 483 |
> |
* Removes the first occurrence of the specified element from this deque. |
| 484 |
> |
* If the deque does not contain the element, it is unchanged. |
| 485 |
> |
* More formally, removes the first element <tt>e</tt> such that |
| 486 |
> |
* <tt>(o==null ? e==null : o.equals(e))</tt> (if such an element exists). |
| 487 |
> |
* Returns true if this deque contained the specified element (or |
| 488 |
> |
* equivalently, if this deque changed as a result of the call). |
| 489 |
> |
* |
| 490 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
| 491 |
> |
* |
| 492 |
> |
* @param o element to be removed from this deque, if present |
| 493 |
> |
* @return <tt>true</tt> if an element was removed as a result of this call |
| 494 |
> |
* @throws NullPointerException if the specified element is null and this |
| 495 |
> |
* deque does not permit null elements (optional) |
| 496 |
> |
* @throws ClassCastException if the class of the specified element |
| 497 |
> |
* is incompatible with this collection (optional) |
| 498 |
> |
*/ |
| 499 |
> |
boolean remove(Object o); |
| 500 |
> |
|
| 501 |
> |
/** |
| 502 |
> |
* Returns <tt>true</tt> if this deque contains the specified element. |
| 503 |
> |
* More formally, returns <tt>true</tt> if and only if this deque |
| 504 |
> |
* contains at least one element <tt>e</tt> such that <tt>(o==null ? |
| 505 |
> |
* e==null : o.equals(e))</tt>. |
| 506 |
> |
* |
| 507 |
> |
* @param o element whose presence in this deque is to be tested |
| 508 |
> |
* @return <tt>true</tt> if this deque contains the specified element |
| 509 |
> |
* @throws ClassCastException if the type of the specified element |
| 510 |
> |
* is incompatible with this deque (optional) |
| 511 |
> |
* @throws NullPointerException if the specified element is null and this |
| 512 |
> |
* deque does not permit null elements (optional) |
| 513 |
> |
*/ |
| 514 |
> |
boolean contains(Object o); |
| 515 |
> |
|
| 516 |
> |
/** |
| 517 |
> |
* Returns the number of elements in this deque. |
| 518 |
> |
* |
| 519 |
> |
* @return the number of elements in this deque |
| 520 |
> |
*/ |
| 521 |
> |
public int size(); |
| 522 |
|
|
| 523 |
|
/** |
| 524 |
|
* Returns an iterator over the elements in this deque. The elements |
