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| 1 | +/* | |
| 2 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 3 | + * | |
| 4 | + * This code is free software; you can redistribute it and/or modify it | |
| 5 | + * under the terms of the GNU General Public License version 2 only, as | |
| 6 | + * published by the Free Software Foundation. Oracle designates this | |
| 7 | + * particular file as subject to the "Classpath" exception as provided | |
| 8 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 9 | + * | |
| 10 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 11 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 14 | + * accompanied this code). | |
| 15 | + * | |
| 16 | + * You should have received a copy of the GNU General Public License version | |
| 17 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 18 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 19 | + * | |
| 20 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 21 | + * or visit www.oracle.com if you need additional information or have any | |
| 22 | + * questions. | |
| 23 | + */ | |
| 24 | + | |
| 25 | +/* | |
| 26 | + * This file is available under and governed by the GNU General Public | |
| 27 | + * License version 2 only, as published by the Free Software Foundation. | |
| 28 | + * However, the following notice accompanied the original version of this | |
| 29 | + * file: | |
| 30 | + * | |
| 31 | + * Written by Doug Lea with assistance from members of JCP JSR-166 | |
| 32 | + * Expert Group and released to the public domain, as explained at | |
| 33 | + * http://creativecommons.org/publicdomain/zero/1.0/ | |
| 34 | + */ | |
| 35 | + | |
| 36 | +package java.util.concurrent; | |
| 37 | +import java.util.*; | |
| 38 | + | |
| 39 | +/** | |
| 40 | + * A {@link Deque} that additionally supports blocking operations that wait | |
| 41 | + * for the deque to become non-empty when retrieving an element, and wait for | |
| 42 | + * space to become available in the deque when storing an element. | |
| 43 | + * | |
| 44 | + * <p><tt>BlockingDeque</tt> methods come in four forms, with different ways | |
| 45 | + * of handling operations that cannot be satisfied immediately, but may be | |
| 46 | + * satisfied at some point in the future: | |
| 47 | + * one throws an exception, the second returns a special value (either | |
| 48 | + * <tt>null</tt> or <tt>false</tt>, depending on the operation), the third | |
| 49 | + * blocks the current thread indefinitely until the operation can succeed, | |
| 50 | + * and the fourth blocks for only a given maximum time limit before giving | |
| 51 | + * up. These methods are summarized in the following table: | |
| 52 | + * | |
| 53 | + * <p> | |
| 54 | + * <table BORDER CELLPADDING=3 CELLSPACING=1> | |
| 55 | + * <tr> | |
| 56 | + * <td ALIGN=CENTER COLSPAN = 5> <b>First Element (Head)</b></td> | |
| 57 | + * </tr> | |
| 58 | + * <tr> | |
| 59 | + * <td></td> | |
| 60 | + * <td ALIGN=CENTER><em>Throws exception</em></td> | |
| 61 | + * <td ALIGN=CENTER><em>Special value</em></td> | |
| 62 | + * <td ALIGN=CENTER><em>Blocks</em></td> | |
| 63 | + * <td ALIGN=CENTER><em>Times out</em></td> | |
| 64 | + * </tr> | |
| 65 | + * <tr> | |
| 66 | + * <td><b>Insert</b></td> | |
| 67 | + * <td>{@link #addFirst addFirst(e)}</td> | |
| 68 | + * <td>{@link #offerFirst(Object) offerFirst(e)}</td> | |
| 69 | + * <td>{@link #putFirst putFirst(e)}</td> | |
| 70 | + * <td>{@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)}</td> | |
| 71 | + * </tr> | |
| 72 | + * <tr> | |
| 73 | + * <td><b>Remove</b></td> | |
| 74 | + * <td>{@link #removeFirst removeFirst()}</td> | |
| 75 | + * <td>{@link #pollFirst pollFirst()}</td> | |
| 76 | + * <td>{@link #takeFirst takeFirst()}</td> | |
| 77 | + * <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> | |
| 78 | + * </tr> | |
| 79 | + * <tr> | |
| 80 | + * <td><b>Examine</b></td> | |
| 81 | + * <td>{@link #getFirst getFirst()}</td> | |
| 82 | + * <td>{@link #peekFirst peekFirst()}</td> | |
| 83 | + * <td><em>not applicable</em></td> | |
| 84 | + * <td><em>not applicable</em></td> | |
| 85 | + * </tr> | |
| 86 | + * <tr> | |
| 87 | + * <td ALIGN=CENTER COLSPAN = 5> <b>Last Element (Tail)</b></td> | |
| 88 | + * </tr> | |
| 89 | + * <tr> | |
| 90 | + * <td></td> | |
| 91 | + * <td ALIGN=CENTER><em>Throws exception</em></td> | |
| 92 | + * <td ALIGN=CENTER><em>Special value</em></td> | |
| 93 | + * <td ALIGN=CENTER><em>Blocks</em></td> | |
| 94 | + * <td ALIGN=CENTER><em>Times out</em></td> | |
| 95 | + * </tr> | |
| 96 | + * <tr> | |
| 97 | + * <td><b>Insert</b></td> | |
| 98 | + * <td>{@link #addLast addLast(e)}</td> | |
| 99 | + * <td>{@link #offerLast(Object) offerLast(e)}</td> | |
| 100 | + * <td>{@link #putLast putLast(e)}</td> | |
| 101 | + * <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> | |
| 102 | + * </tr> | |
| 103 | + * <tr> | |
| 104 | + * <td><b>Remove</b></td> | |
| 105 | + * <td>{@link #removeLast() removeLast()}</td> | |
| 106 | + * <td>{@link #pollLast() pollLast()}</td> | |
| 107 | + * <td>{@link #takeLast takeLast()}</td> | |
| 108 | + * <td>{@link #pollLast(long, TimeUnit) pollLast(time, unit)}</td> | |
| 109 | + * </tr> | |
| 110 | + * <tr> | |
| 111 | + * <td><b>Examine</b></td> | |
| 112 | + * <td>{@link #getLast getLast()}</td> | |
| 113 | + * <td>{@link #peekLast peekLast()}</td> | |
| 114 | + * <td><em>not applicable</em></td> | |
| 115 | + * <td><em>not applicable</em></td> | |
| 116 | + * </tr> | |
| 117 | + * </table> | |
| 118 | + * | |
| 119 | + * <p>Like any {@link BlockingQueue}, a <tt>BlockingDeque</tt> is thread safe, | |
| 120 | + * does not permit null elements, and may (or may not) be | |
| 121 | + * capacity-constrained. | |
| 122 | + * | |
| 123 | + * <p>A <tt>BlockingDeque</tt> implementation may be used directly as a FIFO | |
| 124 | + * <tt>BlockingQueue</tt>. The methods inherited from the | |
| 125 | + * <tt>BlockingQueue</tt> interface are precisely equivalent to | |
| 126 | + * <tt>BlockingDeque</tt> methods as indicated in the following table: | |
| 127 | + * | |
| 128 | + * <p> | |
| 129 | + * <table BORDER CELLPADDING=3 CELLSPACING=1> | |
| 130 | + * <tr> | |
| 131 | + * <td ALIGN=CENTER> <b><tt>BlockingQueue</tt> Method</b></td> | |
| 132 | + * <td ALIGN=CENTER> <b>Equivalent <tt>BlockingDeque</tt> Method</b></td> | |
| 133 | + * </tr> | |
| 134 | + * <tr> | |
| 135 | + * <td ALIGN=CENTER COLSPAN = 2> <b>Insert</b></td> | |
| 136 | + * </tr> | |
| 137 | + * <tr> | |
| 138 | + * <td>{@link #add(Object) add(e)}</td> | |
| 139 | + * <td>{@link #addLast(Object) addLast(e)}</td> | |
| 140 | + * </tr> | |
| 141 | + * <tr> | |
| 142 | + * <td>{@link #offer(Object) offer(e)}</td> | |
| 143 | + * <td>{@link #offerLast(Object) offerLast(e)}</td> | |
| 144 | + * </tr> | |
| 145 | + * <tr> | |
| 146 | + * <td>{@link #put(Object) put(e)}</td> | |
| 147 | + * <td>{@link #putLast(Object) putLast(e)}</td> | |
| 148 | + * </tr> | |
| 149 | + * <tr> | |
| 150 | + * <td>{@link #offer(Object, long, TimeUnit) offer(e, time, unit)}</td> | |
| 151 | + * <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> | |
| 152 | + * </tr> | |
| 153 | + * <tr> | |
| 154 | + * <td ALIGN=CENTER COLSPAN = 2> <b>Remove</b></td> | |
| 155 | + * </tr> | |
| 156 | + * <tr> | |
| 157 | + * <td>{@link #remove() remove()}</td> | |
| 158 | + * <td>{@link #removeFirst() removeFirst()}</td> | |
| 159 | + * </tr> | |
| 160 | + * <tr> | |
| 161 | + * <td>{@link #poll() poll()}</td> | |
| 162 | + * <td>{@link #pollFirst() pollFirst()}</td> | |
| 163 | + * </tr> | |
| 164 | + * <tr> | |
| 165 | + * <td>{@link #take() take()}</td> | |
| 166 | + * <td>{@link #takeFirst() takeFirst()}</td> | |
| 167 | + * </tr> | |
| 168 | + * <tr> | |
| 169 | + * <td>{@link #poll(long, TimeUnit) poll(time, unit)}</td> | |
| 170 | + * <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> | |
| 171 | + * </tr> | |
| 172 | + * <tr> | |
| 173 | + * <td ALIGN=CENTER COLSPAN = 2> <b>Examine</b></td> | |
| 174 | + * </tr> | |
| 175 | + * <tr> | |
| 176 | + * <td>{@link #element() element()}</td> | |
| 177 | + * <td>{@link #getFirst() getFirst()}</td> | |
| 178 | + * </tr> | |
| 179 | + * <tr> | |
| 180 | + * <td>{@link #peek() peek()}</td> | |
| 181 | + * <td>{@link #peekFirst() peekFirst()}</td> | |
| 182 | + * </tr> | |
| 183 | + * </table> | |
| 184 | + * | |
| 185 | + * <p>Memory consistency effects: As with other concurrent | |
| 186 | + * collections, actions in a thread prior to placing an object into a | |
| 187 | + * {@code BlockingDeque} | |
| 188 | + * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> | |
| 189 | + * actions subsequent to the access or removal of that element from | |
| 190 | + * the {@code BlockingDeque} in another thread. | |
| 191 | + * | |
| 192 | + * <p>This interface is a member of the | |
| 193 | + * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | |
| 194 | + * Java Collections Framework</a>. | |
| 195 | + * | |
| 196 | + * @since 1.6 | |
| 197 | + * @author Doug Lea | |
| 198 | + * @param <E> the type of elements held in this collection | |
| 199 | + */ | |
| 200 | +public interface BlockingDeque<E> extends BlockingQueue<E>, Deque<E> { | |
| 201 | + /* | |
| 202 | + * We have "diamond" multiple interface inheritance here, and that | |
| 203 | + * introduces ambiguities. Methods might end up with different | |
| 204 | + * specs depending on the branch chosen by javadoc. Thus a lot of | |
| 205 | + * methods specs here are copied from superinterfaces. | |
| 206 | + */ | |
| 207 | + | |
| 208 | + /** | |
| 209 | + * Inserts the specified element at the front of this deque if it is | |
| 210 | + * possible to do so immediately without violating capacity restrictions, | |
| 211 | + * throwing an <tt>IllegalStateException</tt> if no space is currently | |
| 212 | + * available. When using a capacity-restricted deque, it is generally | |
| 213 | + * preferable to use {@link #offerFirst(Object) offerFirst}. | |
| 214 | + * | |
| 215 | + * @param e the element to add | |
| 216 | + * @throws IllegalStateException {@inheritDoc} | |
| 217 | + * @throws ClassCastException {@inheritDoc} | |
| 218 | + * @throws NullPointerException if the specified element is null | |
| 219 | + * @throws IllegalArgumentException {@inheritDoc} | |
| 220 | + */ | |
| 221 | + void addFirst(E e); | |
| 222 | + | |
| 223 | + /** | |
| 224 | + * Inserts the specified element at the end of this deque if it is | |
| 225 | + * possible to do so immediately without violating capacity restrictions, | |
| 226 | + * throwing an <tt>IllegalStateException</tt> if no space is currently | |
| 227 | + * available. When using a capacity-restricted deque, it is generally | |
| 228 | + * preferable to use {@link #offerLast(Object) offerLast}. | |
| 229 | + * | |
| 230 | + * @param e the element to add | |
| 231 | + * @throws IllegalStateException {@inheritDoc} | |
| 232 | + * @throws ClassCastException {@inheritDoc} | |
| 233 | + * @throws NullPointerException if the specified element is null | |
| 234 | + * @throws IllegalArgumentException {@inheritDoc} | |
| 235 | + */ | |
| 236 | + void addLast(E e); | |
| 237 | + | |
| 238 | + /** | |
| 239 | + * Inserts the specified element at the front of this deque if it is | |
| 240 | + * possible to do so immediately without violating capacity restrictions, | |
| 241 | + * returning <tt>true</tt> upon success and <tt>false</tt> if no space is | |
| 242 | + * currently available. | |
| 243 | + * When using a capacity-restricted deque, this method is generally | |
| 244 | + * preferable to the {@link #addFirst(Object) addFirst} method, which can | |
| 245 | + * fail to insert an element only by throwing an exception. | |
| 246 | + * | |
| 247 | + * @param e the element to add | |
| 248 | + * @throws ClassCastException {@inheritDoc} | |
| 249 | + * @throws NullPointerException if the specified element is null | |
| 250 | + * @throws IllegalArgumentException {@inheritDoc} | |
| 251 | + */ | |
| 252 | + boolean offerFirst(E e); | |
| 253 | + | |
| 254 | + /** | |
| 255 | + * Inserts the specified element at the end of this deque if it is | |
| 256 | + * possible to do so immediately without violating capacity restrictions, | |
| 257 | + * returning <tt>true</tt> upon success and <tt>false</tt> if no space is | |
| 258 | + * currently available. | |
| 259 | + * When using a capacity-restricted deque, this method is generally | |
| 260 | + * preferable to the {@link #addLast(Object) addLast} method, which can | |
| 261 | + * fail to insert an element only by throwing an exception. | |
| 262 | + * | |
| 263 | + * @param e the element to add | |
| 264 | + * @throws ClassCastException {@inheritDoc} | |
| 265 | + * @throws NullPointerException if the specified element is null | |
| 266 | + * @throws IllegalArgumentException {@inheritDoc} | |
| 267 | + */ | |
| 268 | + boolean offerLast(E e); | |
| 269 | + | |
| 270 | + /** | |
| 271 | + * Inserts the specified element at the front of this deque, | |
| 272 | + * waiting if necessary for space to become available. | |
| 273 | + * | |
| 274 | + * @param e the element to add | |
| 275 | + * @throws InterruptedException if interrupted while waiting | |
| 276 | + * @throws ClassCastException if the class of the specified element | |
| 277 | + * prevents it from being added to this deque | |
| 278 | + * @throws NullPointerException if the specified element is null | |
| 279 | + * @throws IllegalArgumentException if some property of the specified | |
| 280 | + * element prevents it from being added to this deque | |
| 281 | + */ | |
| 282 | + void putFirst(E e) throws InterruptedException; | |
| 283 | + | |
| 284 | + /** | |
| 285 | + * Inserts the specified element at the end of this deque, | |
| 286 | + * waiting if necessary for space to become available. | |
| 287 | + * | |
| 288 | + * @param e the element to add | |
| 289 | + * @throws InterruptedException if interrupted while waiting | |
| 290 | + * @throws ClassCastException if the class of the specified element | |
| 291 | + * prevents it from being added to this deque | |
| 292 | + * @throws NullPointerException if the specified element is null | |
| 293 | + * @throws IllegalArgumentException if some property of the specified | |
| 294 | + * element prevents it from being added to this deque | |
| 295 | + */ | |
| 296 | + void putLast(E e) throws InterruptedException; | |
| 297 | + | |
| 298 | + /** | |
| 299 | + * Inserts the specified element at the front of this deque, | |
| 300 | + * waiting up to the specified wait time if necessary for space to | |
| 301 | + * become available. | |
| 302 | + * | |
| 303 | + * @param e the element to add | |
| 304 | + * @param timeout how long to wait before giving up, in units of | |
| 305 | + * <tt>unit</tt> | |
| 306 | + * @param unit a <tt>TimeUnit</tt> determining how to interpret the | |
| 307 | + * <tt>timeout</tt> parameter | |
| 308 | + * @return <tt>true</tt> if successful, or <tt>false</tt> if | |
| 309 | + * the specified waiting time elapses before space is available | |
| 310 | + * @throws InterruptedException if interrupted while waiting | |
| 311 | + * @throws ClassCastException if the class of the specified element | |
| 312 | + * prevents it from being added to this deque | |
| 313 | + * @throws NullPointerException if the specified element is null | |
| 314 | + * @throws IllegalArgumentException if some property of the specified | |
| 315 | + * element prevents it from being added to this deque | |
| 316 | + */ | |
| 317 | + boolean offerFirst(E e, long timeout, TimeUnit unit) | |
| 318 | + throws InterruptedException; | |
| 319 | + | |
| 320 | + /** | |
| 321 | + * Inserts the specified element at the end of this deque, | |
| 322 | + * waiting up to the specified wait time if necessary for space to | |
| 323 | + * become available. | |
| 324 | + * | |
| 325 | + * @param e the element to add | |
| 326 | + * @param timeout how long to wait before giving up, in units of | |
| 327 | + * <tt>unit</tt> | |
| 328 | + * @param unit a <tt>TimeUnit</tt> determining how to interpret the | |
| 329 | + * <tt>timeout</tt> parameter | |
| 330 | + * @return <tt>true</tt> if successful, or <tt>false</tt> if | |
| 331 | + * the specified waiting time elapses before space is available | |
| 332 | + * @throws InterruptedException if interrupted while waiting | |
| 333 | + * @throws ClassCastException if the class of the specified element | |
| 334 | + * prevents it from being added to this deque | |
| 335 | + * @throws NullPointerException if the specified element is null | |
| 336 | + * @throws IllegalArgumentException if some property of the specified | |
| 337 | + * element prevents it from being added to this deque | |
| 338 | + */ | |
| 339 | + boolean offerLast(E e, long timeout, TimeUnit unit) | |
| 340 | + throws InterruptedException; | |
| 341 | + | |
| 342 | + /** | |
| 343 | + * Retrieves and removes the first element of this deque, waiting | |
| 344 | + * if necessary until an element becomes available. | |
| 345 | + * | |
| 346 | + * @return the head of this deque | |
| 347 | + * @throws InterruptedException if interrupted while waiting | |
| 348 | + */ | |
| 349 | + E takeFirst() throws InterruptedException; | |
| 350 | + | |
| 351 | + /** | |
| 352 | + * Retrieves and removes the last element of this deque, waiting | |
| 353 | + * if necessary until an element becomes available. | |
| 354 | + * | |
| 355 | + * @return the tail of this deque | |
| 356 | + * @throws InterruptedException if interrupted while waiting | |
| 357 | + */ | |
| 358 | + E takeLast() throws InterruptedException; | |
| 359 | + | |
| 360 | + /** | |
| 361 | + * Retrieves and removes the first element of this deque, waiting | |
| 362 | + * up to the specified wait time if necessary for an element to | |
| 363 | + * become available. | |
| 364 | + * | |
| 365 | + * @param timeout how long to wait before giving up, in units of | |
| 366 | + * <tt>unit</tt> | |
| 367 | + * @param unit a <tt>TimeUnit</tt> determining how to interpret the | |
| 368 | + * <tt>timeout</tt> parameter | |
| 369 | + * @return the head of this deque, or <tt>null</tt> if the specified | |
| 370 | + * waiting time elapses before an element is available | |
| 371 | + * @throws InterruptedException if interrupted while waiting | |
| 372 | + */ | |
| 373 | + E pollFirst(long timeout, TimeUnit unit) | |
| 374 | + throws InterruptedException; | |
| 375 | + | |
| 376 | + /** | |
| 377 | + * Retrieves and removes the last element of this deque, waiting | |
| 378 | + * up to the specified wait time if necessary for an element to | |
| 379 | + * become available. | |
| 380 | + * | |
| 381 | + * @param timeout how long to wait before giving up, in units of | |
| 382 | + * <tt>unit</tt> | |
| 383 | + * @param unit a <tt>TimeUnit</tt> determining how to interpret the | |
| 384 | + * <tt>timeout</tt> parameter | |
| 385 | + * @return the tail of this deque, or <tt>null</tt> if the specified | |
| 386 | + * waiting time elapses before an element is available | |
| 387 | + * @throws InterruptedException if interrupted while waiting | |
| 388 | + */ | |
| 389 | + E pollLast(long timeout, TimeUnit unit) | |
| 390 | + throws InterruptedException; | |
| 391 | + | |
| 392 | + /** | |
| 393 | + * Removes the first occurrence of the specified element from this deque. | |
| 394 | + * If the deque does not contain the element, it is unchanged. | |
| 395 | + * More formally, removes the first element <tt>e</tt> such that | |
| 396 | + * <tt>o.equals(e)</tt> (if such an element exists). | |
| 397 | + * Returns <tt>true</tt> if this deque contained the specified element | |
| 398 | + * (or equivalently, if this deque changed as a result of the call). | |
| 399 | + * | |
| 400 | + * @param o element to be removed from this deque, if present | |
| 401 | + * @return <tt>true</tt> if an element was removed as a result of this call | |
| 402 | + * @throws ClassCastException if the class of the specified element | |
| 403 | + * is incompatible with this deque | |
| 404 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 405 | + * @throws NullPointerException if the specified element is null | |
| 406 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 407 | + */ | |
| 408 | + boolean removeFirstOccurrence(Object o); | |
| 409 | + | |
| 410 | + /** | |
| 411 | + * Removes the last occurrence of the specified element from this deque. | |
| 412 | + * If the deque does not contain the element, it is unchanged. | |
| 413 | + * More formally, removes the last element <tt>e</tt> such that | |
| 414 | + * <tt>o.equals(e)</tt> (if such an element exists). | |
| 415 | + * Returns <tt>true</tt> if this deque contained the specified element | |
| 416 | + * (or equivalently, if this deque changed as a result of the call). | |
| 417 | + * | |
| 418 | + * @param o element to be removed from this deque, if present | |
| 419 | + * @return <tt>true</tt> if an element was removed as a result of this call | |
| 420 | + * @throws ClassCastException if the class of the specified element | |
| 421 | + * is incompatible with this deque | |
| 422 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 423 | + * @throws NullPointerException if the specified element is null | |
| 424 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 425 | + */ | |
| 426 | + boolean removeLastOccurrence(Object o); | |
| 427 | + | |
| 428 | + // *** BlockingQueue methods *** | |
| 429 | + | |
| 430 | + /** | |
| 431 | + * Inserts the specified element into the queue represented by this deque | |
| 432 | + * (in other words, at the tail of this deque) if it is possible to do so | |
| 433 | + * immediately without violating capacity restrictions, returning | |
| 434 | + * <tt>true</tt> upon success and throwing an | |
| 435 | + * <tt>IllegalStateException</tt> if no space is currently available. | |
| 436 | + * When using a capacity-restricted deque, it is generally preferable to | |
| 437 | + * use {@link #offer(Object) offer}. | |
| 438 | + * | |
| 439 | + * <p>This method is equivalent to {@link #addLast(Object) addLast}. | |
| 440 | + * | |
| 441 | + * @param e the element to add | |
| 442 | + * @throws IllegalStateException {@inheritDoc} | |
| 443 | + * @throws ClassCastException if the class of the specified element | |
| 444 | + * prevents it from being added to this deque | |
| 445 | + * @throws NullPointerException if the specified element is null | |
| 446 | + * @throws IllegalArgumentException if some property of the specified | |
| 447 | + * element prevents it from being added to this deque | |
| 448 | + */ | |
| 449 | + boolean add(E e); | |
| 450 | + | |
| 451 | + /** | |
| 452 | + * Inserts the specified element into the queue represented by this deque | |
| 453 | + * (in other words, at the tail of this deque) if it is possible to do so | |
| 454 | + * immediately without violating capacity restrictions, returning | |
| 455 | + * <tt>true</tt> upon success and <tt>false</tt> if no space is currently | |
| 456 | + * available. When using a capacity-restricted deque, this method is | |
| 457 | + * generally preferable to the {@link #add} method, which can fail to | |
| 458 | + * insert an element only by throwing an exception. | |
| 459 | + * | |
| 460 | + * <p>This method is equivalent to {@link #offerLast(Object) offerLast}. | |
| 461 | + * | |
| 462 | + * @param e the element to add | |
| 463 | + * @throws ClassCastException if the class of the specified element | |
| 464 | + * prevents it from being added to this deque | |
| 465 | + * @throws NullPointerException if the specified element is null | |
| 466 | + * @throws IllegalArgumentException if some property of the specified | |
| 467 | + * element prevents it from being added to this deque | |
| 468 | + */ | |
| 469 | + boolean offer(E e); | |
| 470 | + | |
| 471 | + /** | |
| 472 | + * Inserts the specified element into the queue represented by this deque | |
| 473 | + * (in other words, at the tail of this deque), waiting if necessary for | |
| 474 | + * space to become available. | |
| 475 | + * | |
| 476 | + * <p>This method is equivalent to {@link #putLast(Object) putLast}. | |
| 477 | + * | |
| 478 | + * @param e the element to add | |
| 479 | + * @throws InterruptedException {@inheritDoc} | |
| 480 | + * @throws ClassCastException if the class of the specified element | |
| 481 | + * prevents it from being added to this deque | |
| 482 | + * @throws NullPointerException if the specified element is null | |
| 483 | + * @throws IllegalArgumentException if some property of the specified | |
| 484 | + * element prevents it from being added to this deque | |
| 485 | + */ | |
| 486 | + void put(E e) throws InterruptedException; | |
| 487 | + | |
| 488 | + /** | |
| 489 | + * Inserts the specified element into the queue represented by this deque | |
| 490 | + * (in other words, at the tail of this deque), waiting up to the | |
| 491 | + * specified wait time if necessary for space to become available. | |
| 492 | + * | |
| 493 | + * <p>This method is equivalent to | |
| 494 | + * {@link #offerLast(Object,long,TimeUnit) offerLast}. | |
| 495 | + * | |
| 496 | + * @param e the element to add | |
| 497 | + * @return <tt>true</tt> if the element was added to this deque, else | |
| 498 | + * <tt>false</tt> | |
| 499 | + * @throws InterruptedException {@inheritDoc} | |
| 500 | + * @throws ClassCastException if the class of the specified element | |
| 501 | + * prevents it from being added to this deque | |
| 502 | + * @throws NullPointerException if the specified element is null | |
| 503 | + * @throws IllegalArgumentException if some property of the specified | |
| 504 | + * element prevents it from being added to this deque | |
| 505 | + */ | |
| 506 | + boolean offer(E e, long timeout, TimeUnit unit) | |
| 507 | + throws InterruptedException; | |
| 508 | + | |
| 509 | + /** | |
| 510 | + * Retrieves and removes the head of the queue represented by this deque | |
| 511 | + * (in other words, the first element of this deque). | |
| 512 | + * This method differs from {@link #poll poll} only in that it | |
| 513 | + * throws an exception if this deque is empty. | |
| 514 | + * | |
| 515 | + * <p>This method is equivalent to {@link #removeFirst() removeFirst}. | |
| 516 | + * | |
| 517 | + * @return the head of the queue represented by this deque | |
| 518 | + * @throws NoSuchElementException if this deque is empty | |
| 519 | + */ | |
| 520 | + E remove(); | |
| 521 | + | |
| 522 | + /** | |
| 523 | + * Retrieves and removes the head of the queue represented by this deque | |
| 524 | + * (in other words, the first element of this deque), or returns | |
| 525 | + * <tt>null</tt> if this deque is empty. | |
| 526 | + * | |
| 527 | + * <p>This method is equivalent to {@link #pollFirst()}. | |
| 528 | + * | |
| 529 | + * @return the head of this deque, or <tt>null</tt> if this deque is empty | |
| 530 | + */ | |
| 531 | + E poll(); | |
| 532 | + | |
| 533 | + /** | |
| 534 | + * Retrieves and removes the head of the queue represented by this deque | |
| 535 | + * (in other words, the first element of this deque), waiting if | |
| 536 | + * necessary until an element becomes available. | |
| 537 | + * | |
| 538 | + * <p>This method is equivalent to {@link #takeFirst() takeFirst}. | |
| 539 | + * | |
| 540 | + * @return the head of this deque | |
| 541 | + * @throws InterruptedException if interrupted while waiting | |
| 542 | + */ | |
| 543 | + E take() throws InterruptedException; | |
| 544 | + | |
| 545 | + /** | |
| 546 | + * Retrieves and removes the head of the queue represented by this deque | |
| 547 | + * (in other words, the first element of this deque), waiting up to the | |
| 548 | + * specified wait time if necessary for an element to become available. | |
| 549 | + * | |
| 550 | + * <p>This method is equivalent to | |
| 551 | + * {@link #pollFirst(long,TimeUnit) pollFirst}. | |
| 552 | + * | |
| 553 | + * @return the head of this deque, or <tt>null</tt> if the | |
| 554 | + * specified waiting time elapses before an element is available | |
| 555 | + * @throws InterruptedException if interrupted while waiting | |
| 556 | + */ | |
| 557 | + E poll(long timeout, TimeUnit unit) | |
| 558 | + throws InterruptedException; | |
| 559 | + | |
| 560 | + /** | |
| 561 | + * Retrieves, but does not remove, the head of the queue represented by | |
| 562 | + * this deque (in other words, the first element of this deque). | |
| 563 | + * This method differs from {@link #peek peek} only in that it throws an | |
| 564 | + * exception if this deque is empty. | |
| 565 | + * | |
| 566 | + * <p>This method is equivalent to {@link #getFirst() getFirst}. | |
| 567 | + * | |
| 568 | + * @return the head of this deque | |
| 569 | + * @throws NoSuchElementException if this deque is empty | |
| 570 | + */ | |
| 571 | + E element(); | |
| 572 | + | |
| 573 | + /** | |
| 574 | + * Retrieves, but does not remove, the head of the queue represented by | |
| 575 | + * this deque (in other words, the first element of this deque), or | |
| 576 | + * returns <tt>null</tt> if this deque is empty. | |
| 577 | + * | |
| 578 | + * <p>This method is equivalent to {@link #peekFirst() peekFirst}. | |
| 579 | + * | |
| 580 | + * @return the head of this deque, or <tt>null</tt> if this deque is empty | |
| 581 | + */ | |
| 582 | + E peek(); | |
| 583 | + | |
| 584 | + /** | |
| 585 | + * Removes the first occurrence of the specified element from this deque. | |
| 586 | + * If the deque does not contain the element, it is unchanged. | |
| 587 | + * More formally, removes the first element <tt>e</tt> such that | |
| 588 | + * <tt>o.equals(e)</tt> (if such an element exists). | |
| 589 | + * Returns <tt>true</tt> if this deque contained the specified element | |
| 590 | + * (or equivalently, if this deque changed as a result of the call). | |
| 591 | + * | |
| 592 | + * <p>This method is equivalent to | |
| 593 | + * {@link #removeFirstOccurrence(Object) removeFirstOccurrence}. | |
| 594 | + * | |
| 595 | + * @param o element to be removed from this deque, if present | |
| 596 | + * @return <tt>true</tt> if this deque changed as a result of the call | |
| 597 | + * @throws ClassCastException if the class of the specified element | |
| 598 | + * is incompatible with this deque | |
| 599 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 600 | + * @throws NullPointerException if the specified element is null | |
| 601 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 602 | + */ | |
| 603 | + boolean remove(Object o); | |
| 604 | + | |
| 605 | + /** | |
| 606 | + * Returns <tt>true</tt> if this deque contains the specified element. | |
| 607 | + * More formally, returns <tt>true</tt> if and only if this deque contains | |
| 608 | + * at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. | |
| 609 | + * | |
| 610 | + * @param o object to be checked for containment in this deque | |
| 611 | + * @return <tt>true</tt> if this deque contains the specified element | |
| 612 | + * @throws ClassCastException if the class of the specified element | |
| 613 | + * is incompatible with this deque | |
| 614 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 615 | + * @throws NullPointerException if the specified element is null | |
| 616 | + * (<a href="../Collection.html#optional-restrictions">optional</a>) | |
| 617 | + */ | |
| 618 | + public boolean contains(Object o); | |
| 619 | + | |
| 620 | + /** | |
| 621 | + * Returns the number of elements in this deque. | |
| 622 | + * | |
| 623 | + * @return the number of elements in this deque | |
| 624 | + */ | |
| 625 | + public int size(); | |
| 626 | + | |
| 627 | + /** | |
| 628 | + * Returns an iterator over the elements in this deque in proper sequence. | |
| 629 | + * The elements will be returned in order from first (head) to last (tail). | |
| 630 | + * | |
| 631 | + * @return an iterator over the elements in this deque in proper sequence | |
| 632 | + */ | |
| 633 | + Iterator<E> iterator(); | |
| 634 | + | |
| 635 | + // *** Stack methods *** | |
| 636 | + | |
| 637 | + /** | |
| 638 | + * Pushes an element onto the stack represented by this deque. In other | |
| 639 | + * words, inserts the element at the front of this deque unless it would | |
| 640 | + * violate capacity restrictions. | |
| 641 | + * | |
| 642 | + * <p>This method is equivalent to {@link #addFirst(Object) addFirst}. | |
| 643 | + * | |
| 644 | + * @throws IllegalStateException {@inheritDoc} | |
| 645 | + * @throws ClassCastException {@inheritDoc} | |
| 646 | + * @throws NullPointerException if the specified element is null | |
| 647 | + * @throws IllegalArgumentException {@inheritDoc} | |
| 648 | + */ | |
| 649 | + void push(E e); | |
| 650 | +} | |