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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 | } | ||