1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/rt/emul/compact/src/main/java/java/util/Deque.java Tue Feb 26 16:54:16 2013 +0100
1.3 @@ -0,0 +1,584 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.6 + *
1.7 + * This code is free software; you can redistribute it and/or modify it
1.8 + * under the terms of the GNU General Public License version 2 only, as
1.9 + * published by the Free Software Foundation. Oracle designates this
1.10 + * particular file as subject to the "Classpath" exception as provided
1.11 + * by Oracle in the LICENSE file that accompanied this code.
1.12 + *
1.13 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.14 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.15 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.16 + * version 2 for more details (a copy is included in the LICENSE file that
1.17 + * accompanied this code).
1.18 + *
1.19 + * You should have received a copy of the GNU General Public License version
1.20 + * 2 along with this work; if not, write to the Free Software Foundation,
1.21 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.22 + *
1.23 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.24 + * or visit www.oracle.com if you need additional information or have any
1.25 + * questions.
1.26 + */
1.27 +
1.28 +/*
1.29 + * This file is available under and governed by the GNU General Public
1.30 + * License version 2 only, as published by the Free Software Foundation.
1.31 + * However, the following notice accompanied the original version of this
1.32 + * file:
1.33 + *
1.34 + * Written by Doug Lea and Josh Bloch with assistance from members of
1.35 + * JCP JSR-166 Expert Group and released to the public domain, as explained
1.36 + * at http://creativecommons.org/publicdomain/zero/1.0/
1.37 + */
1.38 +
1.39 +package java.util;
1.40 +
1.41 +/**
1.42 + * A linear collection that supports element insertion and removal at
1.43 + * both ends. The name <i>deque</i> is short for "double ended queue"
1.44 + * and is usually pronounced "deck". Most <tt>Deque</tt>
1.45 + * implementations place no fixed limits on the number of elements
1.46 + * they may contain, but this interface supports capacity-restricted
1.47 + * deques as well as those with no fixed size limit.
1.48 + *
1.49 + * <p>This interface defines methods to access the elements at both
1.50 + * ends of the deque. Methods are provided to insert, remove, and
1.51 + * examine the element. Each of these methods exists in two forms:
1.52 + * one throws an exception if the operation fails, the other returns a
1.53 + * special value (either <tt>null</tt> or <tt>false</tt>, depending on
1.54 + * the operation). The latter form of the insert operation is
1.55 + * designed specifically for use with capacity-restricted
1.56 + * <tt>Deque</tt> implementations; in most implementations, insert
1.57 + * operations cannot fail.
1.58 + *
1.59 + * <p>The twelve methods described above are summarized in the
1.60 + * following table:
1.61 + *
1.62 + * <p>
1.63 + * <table BORDER CELLPADDING=3 CELLSPACING=1>
1.64 + * <tr>
1.65 + * <td></td>
1.66 + * <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td>
1.67 + * <td ALIGN=CENTER COLSPAN = 2> <b>Last Element (Tail)</b></td>
1.68 + * </tr>
1.69 + * <tr>
1.70 + * <td></td>
1.71 + * <td ALIGN=CENTER><em>Throws exception</em></td>
1.72 + * <td ALIGN=CENTER><em>Special value</em></td>
1.73 + * <td ALIGN=CENTER><em>Throws exception</em></td>
1.74 + * <td ALIGN=CENTER><em>Special value</em></td>
1.75 + * </tr>
1.76 + * <tr>
1.77 + * <td><b>Insert</b></td>
1.78 + * <td>{@link #addFirst addFirst(e)}</td>
1.79 + * <td>{@link #offerFirst offerFirst(e)}</td>
1.80 + * <td>{@link #addLast addLast(e)}</td>
1.81 + * <td>{@link #offerLast offerLast(e)}</td>
1.82 + * </tr>
1.83 + * <tr>
1.84 + * <td><b>Remove</b></td>
1.85 + * <td>{@link #removeFirst removeFirst()}</td>
1.86 + * <td>{@link #pollFirst pollFirst()}</td>
1.87 + * <td>{@link #removeLast removeLast()}</td>
1.88 + * <td>{@link #pollLast pollLast()}</td>
1.89 + * </tr>
1.90 + * <tr>
1.91 + * <td><b>Examine</b></td>
1.92 + * <td>{@link #getFirst getFirst()}</td>
1.93 + * <td>{@link #peekFirst peekFirst()}</td>
1.94 + * <td>{@link #getLast getLast()}</td>
1.95 + * <td>{@link #peekLast peekLast()}</td>
1.96 + * </tr>
1.97 + * </table>
1.98 + *
1.99 + * <p>This interface extends the {@link Queue} interface. When a deque is
1.100 + * used as a queue, FIFO (First-In-First-Out) behavior results. Elements are
1.101 + * added at the end of the deque and removed from the beginning. The methods
1.102 + * inherited from the <tt>Queue</tt> interface are precisely equivalent to
1.103 + * <tt>Deque</tt> methods as indicated in the following table:
1.104 + *
1.105 + * <p>
1.106 + * <table BORDER CELLPADDING=3 CELLSPACING=1>
1.107 + * <tr>
1.108 + * <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td>
1.109 + * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
1.110 + * </tr>
1.111 + * <tr>
1.112 + * <td>{@link java.util.Queue#add add(e)}</td>
1.113 + * <td>{@link #addLast addLast(e)}</td>
1.114 + * </tr>
1.115 + * <tr>
1.116 + * <td>{@link java.util.Queue#offer offer(e)}</td>
1.117 + * <td>{@link #offerLast offerLast(e)}</td>
1.118 + * </tr>
1.119 + * <tr>
1.120 + * <td>{@link java.util.Queue#remove remove()}</td>
1.121 + * <td>{@link #removeFirst removeFirst()}</td>
1.122 + * </tr>
1.123 + * <tr>
1.124 + * <td>{@link java.util.Queue#poll poll()}</td>
1.125 + * <td>{@link #pollFirst pollFirst()}</td>
1.126 + * </tr>
1.127 + * <tr>
1.128 + * <td>{@link java.util.Queue#element element()}</td>
1.129 + * <td>{@link #getFirst getFirst()}</td>
1.130 + * </tr>
1.131 + * <tr>
1.132 + * <td>{@link java.util.Queue#peek peek()}</td>
1.133 + * <td>{@link #peek peekFirst()}</td>
1.134 + * </tr>
1.135 + * </table>
1.136 + *
1.137 + * <p>Deques can also be used as LIFO (Last-In-First-Out) stacks. This
1.138 + * interface should be used in preference to the legacy {@link Stack} class.
1.139 + * When a deque is used as a stack, elements are pushed and popped from the
1.140 + * beginning of the deque. Stack methods are precisely equivalent to
1.141 + * <tt>Deque</tt> methods as indicated in the table below:
1.142 + *
1.143 + * <p>
1.144 + * <table BORDER CELLPADDING=3 CELLSPACING=1>
1.145 + * <tr>
1.146 + * <td ALIGN=CENTER> <b>Stack Method</b></td>
1.147 + * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td>
1.148 + * </tr>
1.149 + * <tr>
1.150 + * <td>{@link #push push(e)}</td>
1.151 + * <td>{@link #addFirst addFirst(e)}</td>
1.152 + * </tr>
1.153 + * <tr>
1.154 + * <td>{@link #pop pop()}</td>
1.155 + * <td>{@link #removeFirst removeFirst()}</td>
1.156 + * </tr>
1.157 + * <tr>
1.158 + * <td>{@link #peek peek()}</td>
1.159 + * <td>{@link #peekFirst peekFirst()}</td>
1.160 + * </tr>
1.161 + * </table>
1.162 + *
1.163 + * <p>Note that the {@link #peek peek} method works equally well when
1.164 + * a deque is used as a queue or a stack; in either case, elements are
1.165 + * drawn from the beginning of the deque.
1.166 + *
1.167 + * <p>This interface provides two methods to remove interior
1.168 + * elements, {@link #removeFirstOccurrence removeFirstOccurrence} and
1.169 + * {@link #removeLastOccurrence removeLastOccurrence}.
1.170 + *
1.171 + * <p>Unlike the {@link List} interface, this interface does not
1.172 + * provide support for indexed access to elements.
1.173 + *
1.174 + * <p>While <tt>Deque</tt> implementations are not strictly required
1.175 + * to prohibit the insertion of null elements, they are strongly
1.176 + * encouraged to do so. Users of any <tt>Deque</tt> implementations
1.177 + * that do allow null elements are strongly encouraged <i>not</i> to
1.178 + * take advantage of the ability to insert nulls. This is so because
1.179 + * <tt>null</tt> is used as a special return value by various methods
1.180 + * to indicated that the deque is empty.
1.181 + *
1.182 + * <p><tt>Deque</tt> implementations generally do not define
1.183 + * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt>
1.184 + * methods, but instead inherit the identity-based versions from class
1.185 + * <tt>Object</tt>.
1.186 + *
1.187 + * <p>This interface is a member of the <a
1.188 + * href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections
1.189 + * Framework</a>.
1.190 + *
1.191 + * @author Doug Lea
1.192 + * @author Josh Bloch
1.193 + * @since 1.6
1.194 + * @param <E> the type of elements held in this collection
1.195 + */
1.196 +
1.197 +public interface Deque<E> extends Queue<E> {
1.198 + /**
1.199 + * Inserts the specified element at the front of this deque if it is
1.200 + * possible to do so immediately without violating capacity restrictions.
1.201 + * When using a capacity-restricted deque, it is generally preferable to
1.202 + * use method {@link #offerFirst}.
1.203 + *
1.204 + * @param e the element to add
1.205 + * @throws IllegalStateException if the element cannot be added at this
1.206 + * time due to capacity restrictions
1.207 + * @throws ClassCastException if the class of the specified element
1.208 + * prevents it from being added to this deque
1.209 + * @throws NullPointerException if the specified element is null and this
1.210 + * deque does not permit null elements
1.211 + * @throws IllegalArgumentException if some property of the specified
1.212 + * element prevents it from being added to this deque
1.213 + */
1.214 + void addFirst(E e);
1.215 +
1.216 + /**
1.217 + * Inserts the specified element at the end of this deque if it is
1.218 + * possible to do so immediately without violating capacity restrictions.
1.219 + * When using a capacity-restricted deque, it is generally preferable to
1.220 + * use method {@link #offerLast}.
1.221 + *
1.222 + * <p>This method is equivalent to {@link #add}.
1.223 + *
1.224 + * @param e the element to add
1.225 + * @throws IllegalStateException if the element cannot be added at this
1.226 + * time due to capacity restrictions
1.227 + * @throws ClassCastException if the class of the specified element
1.228 + * prevents it from being added to this deque
1.229 + * @throws NullPointerException if the specified element is null and this
1.230 + * deque does not permit null elements
1.231 + * @throws IllegalArgumentException if some property of the specified
1.232 + * element prevents it from being added to this deque
1.233 + */
1.234 + void addLast(E e);
1.235 +
1.236 + /**
1.237 + * Inserts the specified element at the front of this deque unless it would
1.238 + * violate capacity restrictions. When using a capacity-restricted deque,
1.239 + * this method is generally preferable to the {@link #addFirst} method,
1.240 + * which can fail to insert an element only by throwing an exception.
1.241 + *
1.242 + * @param e the element to add
1.243 + * @return <tt>true</tt> if the element was added to this deque, else
1.244 + * <tt>false</tt>
1.245 + * @throws ClassCastException if the class of the specified element
1.246 + * prevents it from being added to this deque
1.247 + * @throws NullPointerException if the specified element is null and this
1.248 + * deque does not permit null elements
1.249 + * @throws IllegalArgumentException if some property of the specified
1.250 + * element prevents it from being added to this deque
1.251 + */
1.252 + boolean offerFirst(E e);
1.253 +
1.254 + /**
1.255 + * Inserts the specified element at the end of this deque unless it would
1.256 + * violate capacity restrictions. When using a capacity-restricted deque,
1.257 + * this method is generally preferable to the {@link #addLast} method,
1.258 + * which can fail to insert an element only by throwing an exception.
1.259 + *
1.260 + * @param e the element to add
1.261 + * @return <tt>true</tt> if the element was added to this deque, else
1.262 + * <tt>false</tt>
1.263 + * @throws ClassCastException if the class of the specified element
1.264 + * prevents it from being added to this deque
1.265 + * @throws NullPointerException if the specified element is null and this
1.266 + * deque does not permit null elements
1.267 + * @throws IllegalArgumentException if some property of the specified
1.268 + * element prevents it from being added to this deque
1.269 + */
1.270 + boolean offerLast(E e);
1.271 +
1.272 + /**
1.273 + * Retrieves and removes the first element of this deque. This method
1.274 + * differs from {@link #pollFirst pollFirst} only in that it throws an
1.275 + * exception if this deque is empty.
1.276 + *
1.277 + * @return the head of this deque
1.278 + * @throws NoSuchElementException if this deque is empty
1.279 + */
1.280 + E removeFirst();
1.281 +
1.282 + /**
1.283 + * Retrieves and removes the last element of this deque. This method
1.284 + * differs from {@link #pollLast pollLast} only in that it throws an
1.285 + * exception if this deque is empty.
1.286 + *
1.287 + * @return the tail of this deque
1.288 + * @throws NoSuchElementException if this deque is empty
1.289 + */
1.290 + E removeLast();
1.291 +
1.292 + /**
1.293 + * Retrieves and removes the first element of this deque,
1.294 + * or returns <tt>null</tt> if this deque is empty.
1.295 + *
1.296 + * @return the head of this deque, or <tt>null</tt> if this deque is empty
1.297 + */
1.298 + E pollFirst();
1.299 +
1.300 + /**
1.301 + * Retrieves and removes the last element of this deque,
1.302 + * or returns <tt>null</tt> if this deque is empty.
1.303 + *
1.304 + * @return the tail of this deque, or <tt>null</tt> if this deque is empty
1.305 + */
1.306 + E pollLast();
1.307 +
1.308 + /**
1.309 + * Retrieves, but does not remove, the first element of this deque.
1.310 + *
1.311 + * This method differs from {@link #peekFirst peekFirst} only in that it
1.312 + * throws an exception if this deque is empty.
1.313 + *
1.314 + * @return the head of this deque
1.315 + * @throws NoSuchElementException if this deque is empty
1.316 + */
1.317 + E getFirst();
1.318 +
1.319 + /**
1.320 + * Retrieves, but does not remove, the last element of this deque.
1.321 + * This method differs from {@link #peekLast peekLast} only in that it
1.322 + * throws an exception if this deque is empty.
1.323 + *
1.324 + * @return the tail of this deque
1.325 + * @throws NoSuchElementException if this deque is empty
1.326 + */
1.327 + E getLast();
1.328 +
1.329 + /**
1.330 + * Retrieves, but does not remove, the first element of this deque,
1.331 + * or returns <tt>null</tt> if this deque is empty.
1.332 + *
1.333 + * @return the head of this deque, or <tt>null</tt> if this deque is empty
1.334 + */
1.335 + E peekFirst();
1.336 +
1.337 + /**
1.338 + * Retrieves, but does not remove, the last element of this deque,
1.339 + * or returns <tt>null</tt> if this deque is empty.
1.340 + *
1.341 + * @return the tail of this deque, or <tt>null</tt> if this deque is empty
1.342 + */
1.343 + E peekLast();
1.344 +
1.345 + /**
1.346 + * Removes the first occurrence of the specified element from this deque.
1.347 + * If the deque does not contain the element, it is unchanged.
1.348 + * More formally, removes the first element <tt>e</tt> such that
1.349 + * <tt>(o==null ? e==null : o.equals(e))</tt>
1.350 + * (if such an element exists).
1.351 + * Returns <tt>true</tt> if this deque contained the specified element
1.352 + * (or equivalently, if this deque changed as a result of the call).
1.353 + *
1.354 + * @param o element to be removed from this deque, if present
1.355 + * @return <tt>true</tt> if an element was removed as a result of this call
1.356 + * @throws ClassCastException if the class of the specified element
1.357 + * is incompatible with this deque
1.358 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.359 + * @throws NullPointerException if the specified element is null and this
1.360 + * deque does not permit null elements
1.361 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.362 + */
1.363 + boolean removeFirstOccurrence(Object o);
1.364 +
1.365 + /**
1.366 + * Removes the last occurrence of the specified element from this deque.
1.367 + * If the deque does not contain the element, it is unchanged.
1.368 + * More formally, removes the last element <tt>e</tt> such that
1.369 + * <tt>(o==null ? e==null : o.equals(e))</tt>
1.370 + * (if such an element exists).
1.371 + * Returns <tt>true</tt> if this deque contained the specified element
1.372 + * (or equivalently, if this deque changed as a result of the call).
1.373 + *
1.374 + * @param o element to be removed from this deque, if present
1.375 + * @return <tt>true</tt> if an element was removed as a result of this call
1.376 + * @throws ClassCastException if the class of the specified element
1.377 + * is incompatible with this deque
1.378 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.379 + * @throws NullPointerException if the specified element is null and this
1.380 + * deque does not permit null elements
1.381 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.382 + */
1.383 + boolean removeLastOccurrence(Object o);
1.384 +
1.385 + // *** Queue methods ***
1.386 +
1.387 + /**
1.388 + * Inserts the specified element into the queue represented by this deque
1.389 + * (in other words, at the tail of this deque) if it is possible to do so
1.390 + * immediately without violating capacity restrictions, returning
1.391 + * <tt>true</tt> upon success and throwing an
1.392 + * <tt>IllegalStateException</tt> if no space is currently available.
1.393 + * When using a capacity-restricted deque, it is generally preferable to
1.394 + * use {@link #offer(Object) offer}.
1.395 + *
1.396 + * <p>This method is equivalent to {@link #addLast}.
1.397 + *
1.398 + * @param e the element to add
1.399 + * @return <tt>true</tt> (as specified by {@link Collection#add})
1.400 + * @throws IllegalStateException if the element cannot be added at this
1.401 + * time due to capacity restrictions
1.402 + * @throws ClassCastException if the class of the specified element
1.403 + * prevents it from being added to this deque
1.404 + * @throws NullPointerException if the specified element is null and this
1.405 + * deque does not permit null elements
1.406 + * @throws IllegalArgumentException if some property of the specified
1.407 + * element prevents it from being added to this deque
1.408 + */
1.409 + boolean add(E e);
1.410 +
1.411 + /**
1.412 + * Inserts the specified element into the queue represented by this deque
1.413 + * (in other words, at the tail of this deque) if it is possible to do so
1.414 + * immediately without violating capacity restrictions, returning
1.415 + * <tt>true</tt> upon success and <tt>false</tt> if no space is currently
1.416 + * available. When using a capacity-restricted deque, this method is
1.417 + * generally preferable to the {@link #add} method, which can fail to
1.418 + * insert an element only by throwing an exception.
1.419 + *
1.420 + * <p>This method is equivalent to {@link #offerLast}.
1.421 + *
1.422 + * @param e the element to add
1.423 + * @return <tt>true</tt> if the element was added to this deque, else
1.424 + * <tt>false</tt>
1.425 + * @throws ClassCastException if the class of the specified element
1.426 + * prevents it from being added to this deque
1.427 + * @throws NullPointerException if the specified element is null and this
1.428 + * deque does not permit null elements
1.429 + * @throws IllegalArgumentException if some property of the specified
1.430 + * element prevents it from being added to this deque
1.431 + */
1.432 + boolean offer(E e);
1.433 +
1.434 + /**
1.435 + * Retrieves and removes the head of the queue represented by this deque
1.436 + * (in other words, the first element of this deque).
1.437 + * This method differs from {@link #poll poll} only in that it throws an
1.438 + * exception if this deque is empty.
1.439 + *
1.440 + * <p>This method is equivalent to {@link #removeFirst()}.
1.441 + *
1.442 + * @return the head of the queue represented by this deque
1.443 + * @throws NoSuchElementException if this deque is empty
1.444 + */
1.445 + E remove();
1.446 +
1.447 + /**
1.448 + * Retrieves and removes the head of the queue represented by this deque
1.449 + * (in other words, the first element of this deque), or returns
1.450 + * <tt>null</tt> if this deque is empty.
1.451 + *
1.452 + * <p>This method is equivalent to {@link #pollFirst()}.
1.453 + *
1.454 + * @return the first element of this deque, or <tt>null</tt> if
1.455 + * this deque is empty
1.456 + */
1.457 + E poll();
1.458 +
1.459 + /**
1.460 + * Retrieves, but does not remove, the head of the queue represented by
1.461 + * this deque (in other words, the first element of this deque).
1.462 + * This method differs from {@link #peek peek} only in that it throws an
1.463 + * exception if this deque is empty.
1.464 + *
1.465 + * <p>This method is equivalent to {@link #getFirst()}.
1.466 + *
1.467 + * @return the head of the queue represented by this deque
1.468 + * @throws NoSuchElementException if this deque is empty
1.469 + */
1.470 + E element();
1.471 +
1.472 + /**
1.473 + * Retrieves, but does not remove, the head of the queue represented by
1.474 + * this deque (in other words, the first element of this deque), or
1.475 + * returns <tt>null</tt> if this deque is empty.
1.476 + *
1.477 + * <p>This method is equivalent to {@link #peekFirst()}.
1.478 + *
1.479 + * @return the head of the queue represented by this deque, or
1.480 + * <tt>null</tt> if this deque is empty
1.481 + */
1.482 + E peek();
1.483 +
1.484 +
1.485 + // *** Stack methods ***
1.486 +
1.487 + /**
1.488 + * Pushes an element onto the stack represented by this deque (in other
1.489 + * words, at the head of this deque) if it is possible to do so
1.490 + * immediately without violating capacity restrictions, returning
1.491 + * <tt>true</tt> upon success and throwing an
1.492 + * <tt>IllegalStateException</tt> if no space is currently available.
1.493 + *
1.494 + * <p>This method is equivalent to {@link #addFirst}.
1.495 + *
1.496 + * @param e the element to push
1.497 + * @throws IllegalStateException if the element cannot be added at this
1.498 + * time due to capacity restrictions
1.499 + * @throws ClassCastException if the class of the specified element
1.500 + * prevents it from being added to this deque
1.501 + * @throws NullPointerException if the specified element is null and this
1.502 + * deque does not permit null elements
1.503 + * @throws IllegalArgumentException if some property of the specified
1.504 + * element prevents it from being added to this deque
1.505 + */
1.506 + void push(E e);
1.507 +
1.508 + /**
1.509 + * Pops an element from the stack represented by this deque. In other
1.510 + * words, removes and returns the first element of this deque.
1.511 + *
1.512 + * <p>This method is equivalent to {@link #removeFirst()}.
1.513 + *
1.514 + * @return the element at the front of this deque (which is the top
1.515 + * of the stack represented by this deque)
1.516 + * @throws NoSuchElementException if this deque is empty
1.517 + */
1.518 + E pop();
1.519 +
1.520 +
1.521 + // *** Collection methods ***
1.522 +
1.523 + /**
1.524 + * Removes the first occurrence of the specified element from this deque.
1.525 + * If the deque does not contain the element, it is unchanged.
1.526 + * More formally, removes the first element <tt>e</tt> such that
1.527 + * <tt>(o==null ? e==null : o.equals(e))</tt>
1.528 + * (if such an element exists).
1.529 + * Returns <tt>true</tt> if this deque contained the specified element
1.530 + * (or equivalently, if this deque changed as a result of the call).
1.531 + *
1.532 + * <p>This method is equivalent to {@link #removeFirstOccurrence}.
1.533 + *
1.534 + * @param o element to be removed from this deque, if present
1.535 + * @return <tt>true</tt> if an element was removed as a result of this call
1.536 + * @throws ClassCastException if the class of the specified element
1.537 + * is incompatible with this deque
1.538 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.539 + * @throws NullPointerException if the specified element is null and this
1.540 + * deque does not permit null elements
1.541 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.542 + */
1.543 + boolean remove(Object o);
1.544 +
1.545 + /**
1.546 + * Returns <tt>true</tt> if this deque contains the specified element.
1.547 + * More formally, returns <tt>true</tt> if and only if this deque contains
1.548 + * at least one element <tt>e</tt> such that
1.549 + * <tt>(o==null ? e==null : o.equals(e))</tt>.
1.550 + *
1.551 + * @param o element whose presence in this deque is to be tested
1.552 + * @return <tt>true</tt> if this deque contains the specified element
1.553 + * @throws ClassCastException if the type of the specified element
1.554 + * is incompatible with this deque
1.555 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.556 + * @throws NullPointerException if the specified element is null and this
1.557 + * deque does not permit null elements
1.558 + * (<a href="Collection.html#optional-restrictions">optional</a>)
1.559 + */
1.560 + boolean contains(Object o);
1.561 +
1.562 + /**
1.563 + * Returns the number of elements in this deque.
1.564 + *
1.565 + * @return the number of elements in this deque
1.566 + */
1.567 + public int size();
1.568 +
1.569 + /**
1.570 + * Returns an iterator over the elements in this deque in proper sequence.
1.571 + * The elements will be returned in order from first (head) to last (tail).
1.572 + *
1.573 + * @return an iterator over the elements in this deque in proper sequence
1.574 + */
1.575 + Iterator<E> iterator();
1.576 +
1.577 + /**
1.578 + * Returns an iterator over the elements in this deque in reverse
1.579 + * sequential order. The elements will be returned in order from
1.580 + * last (tail) to first (head).
1.581 + *
1.582 + * @return an iterator over the elements in this deque in reverse
1.583 + * sequence
1.584 + */
1.585 + Iterator<E> descendingIterator();
1.586 +
1.587 +}