16232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson/* 22f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Written by Doug Lea and Josh Bloch with assistance from members of 32f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * JCP JSR-166 Expert Group and released to the public domain, as explained 4a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * at http://creativecommons.org/publicdomain/zero/1.0/ 56232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 66232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 76232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilsonpackage java.util; 86232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 92f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson// BEGIN android-note 102f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson// removed link to collections framework docs 112f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson// END android-note 122f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson/** 142f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * A linear collection that supports element insertion and removal at 152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * both ends. The name <i>deque</i> is short for "double ended queue" 162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * and is usually pronounced "deck". Most <tt>Deque</tt> 172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * implementations place no fixed limits on the number of elements 182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * they may contain, but this interface supports capacity-restricted 192f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deques as well as those with no fixed size limit. 202f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 212f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This interface defines methods to access the elements at both 222f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * ends of the deque. Methods are provided to insert, remove, and 232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * examine the element. Each of these methods exists in two forms: 242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * one throws an exception if the operation fails, the other returns a 252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * special value (either <tt>null</tt> or <tt>false</tt>, depending on 262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * the operation). The latter form of the insert operation is 272f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * designed specifically for use with capacity-restricted 282f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>Deque</tt> implementations; in most implementations, insert 292f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * operations cannot fail. 302f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 312f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>The twelve methods described above are summarized in the 322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * following table: 332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 342f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p> 352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <table BORDER CELLPADDING=3 CELLSPACING=1> 362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 372f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td></td> 382f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td> 392f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER COLSPAN = 2> <b>Last Element (Tail)</b></td> 402f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 422f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td></td> 432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER><em>Throws exception</em></td> 442f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER><em>Special value</em></td> 452f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER><em>Throws exception</em></td> 462f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER><em>Special value</em></td> 472f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 482f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 492f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td><b>Insert</b></td> 502f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #addFirst addFirst(e)}</td> 512f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #offerFirst offerFirst(e)}</td> 522f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #addLast addLast(e)}</td> 532f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #offerLast offerLast(e)}</td> 542f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 552f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 562f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td><b>Remove</b></td> 572f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #removeFirst removeFirst()}</td> 582f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #pollFirst pollFirst()}</td> 592f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #removeLast removeLast()}</td> 602f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #pollLast pollLast()}</td> 612f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 622f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 632f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td><b>Examine</b></td> 642f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #getFirst getFirst()}</td> 652f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #peekFirst peekFirst()}</td> 662f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #getLast getLast()}</td> 672f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #peekLast peekLast()}</td> 682f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 692f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </table> 702f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 712f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This interface extends the {@link Queue} interface. When a deque is 722f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * used as a queue, FIFO (First-In-First-Out) behavior results. Elements are 732f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * added at the end of the deque and removed from the beginning. The methods 742f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * inherited from the <tt>Queue</tt> interface are precisely equivalent to 752f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>Deque</tt> methods as indicated in the following table: 762f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 772f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p> 782f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <table BORDER CELLPADDING=3 CELLSPACING=1> 792f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 802f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td> 812f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> 822f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 832f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 842f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#add add(e)}</td> 852f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #addLast addLast(e)}</td> 862f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 872f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 882f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#offer offer(e)}</td> 892f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #offerLast offerLast(e)}</td> 902f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 912f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 922f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#remove remove()}</td> 932f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #removeFirst removeFirst()}</td> 942f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 952f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 962f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#poll poll()}</td> 972f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #pollFirst pollFirst()}</td> 982f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 992f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1002f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#element element()}</td> 1012f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #getFirst getFirst()}</td> 1022f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1032f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1042f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link java.util.Queue#peek peek()}</td> 1052f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #peek peekFirst()}</td> 1062f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1072f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </table> 1082f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 1092f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>Deques can also be used as LIFO (Last-In-First-Out) stacks. This 1102f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * interface should be used in preference to the legacy {@link Stack} class. 1112f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * When a deque is used as a stack, elements are pushed and popped from the 1122f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * beginning of the deque. Stack methods are precisely equivalent to 1132f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>Deque</tt> methods as indicated in the table below: 1146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p> 1162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <table BORDER CELLPADDING=3 CELLSPACING=1> 1172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER> <b>Stack Method</b></td> 1192f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> 1202f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1212f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1222f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #push push(e)}</td> 1232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #addFirst addFirst(e)}</td> 1242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #pop pop()}</td> 1272f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #removeFirst removeFirst()}</td> 1282f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1292f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tr> 1302f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #peek peek()}</td> 1312f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <td>{@link #peekFirst peekFirst()}</td> 1322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </tr> 1332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * </table> 1346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>Note that the {@link #peek peek} method works equally well when 1362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * a deque is used as a queue or a stack; in either case, elements are 1372f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * drawn from the beginning of the deque. 1386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1392f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This interface provides two methods to remove interior 1402f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * elements, {@link #removeFirstOccurrence removeFirstOccurrence} and 1412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * {@link #removeLastOccurrence removeLastOccurrence}. 1426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>Unlike the {@link List} interface, this interface does not 1442f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * provide support for indexed access to elements. 1452f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 1462f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>While <tt>Deque</tt> implementations are not strictly required 1472f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * to prohibit the insertion of null elements, they are strongly 1482f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * encouraged to do so. Users of any <tt>Deque</tt> implementations 1492f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * that do allow null elements are strongly encouraged <i>not</i> to 1502f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * take advantage of the ability to insert nulls. This is so because 1512f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>null</tt> is used as a special return value by various methods 1522f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * to indicated that the deque is empty. 1532f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 1542f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p><tt>Deque</tt> implementations generally do not define 1552f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt> 1562f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * methods, but instead inherit the identity-based versions from class 1572f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>Object</tt>. 1582f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 1592f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @author Doug Lea 1602f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @author Josh Bloch 1612f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @since 1.6 1622f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param <E> the type of elements held in this collection 1636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1652f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilsonpublic interface Deque<E> extends Queue<E> { 1666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1672f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element at the front of this deque if it is 1682f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * possible to do so immediately without violating capacity restrictions. 1692f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * When using a capacity-restricted deque, it is generally preferable to 1702f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * use method {@link #offerFirst}. 1716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1722f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 1732f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalStateException if the element cannot be added at this 1742f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * time due to capacity restrictions 1752f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 1762f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 1772f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 1782f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 1792f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 1802f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 1816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson void addFirst(E e); 1836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1852f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element at the end of this deque if it is 1862f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * possible to do so immediately without violating capacity restrictions. 1872f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * When using a capacity-restricted deque, it is generally preferable to 1882f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * use method {@link #offerLast}. 1896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1902f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #add}. 1912f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 1922f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 1932f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalStateException if the element cannot be added at this 1942f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * time due to capacity restrictions 1952f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 1962f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 1972f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 1982f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 1992f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 2002f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 2016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson void addLast(E e); 2036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2052f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element at the front of this deque unless it would 2062f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * violate capacity restrictions. When using a capacity-restricted deque, 2072f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * this method is generally preferable to the {@link #addFirst} method, 2082f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * which can fail to insert an element only by throwing an exception. 2096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2102f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 2112f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if the element was added to this deque, else 2122f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>false</tt> 2132f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 2142f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 2152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 2162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 2172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 2182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 2196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean offerFirst(E e); 2216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element at the end of this deque unless it would 2242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * violate capacity restrictions. When using a capacity-restricted deque, 2252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * this method is generally preferable to the {@link #addLast} method, 2262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * which can fail to insert an element only by throwing an exception. 2276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2282f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 2292f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if the element was added to this deque, else 2302f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>false</tt> 2312f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 2322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 2332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 2342f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 2352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 2362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 2376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean offerLast(E e); 2396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the first element of this deque. This method 2422f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * differs from {@link #pollFirst pollFirst} only in that it throws an 2432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * exception if this deque is empty. 2446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2452f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of this deque 2462f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 2476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E removeFirst(); 2496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2512f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the last element of this deque. This method 2522f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * differs from {@link #pollLast pollLast} only in that it throws an 2532f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * exception if this deque is empty. 2546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2552f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the tail of this deque 2562f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 2576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E removeLast(); 2596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2612f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the first element of this deque, 2622f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * or returns <tt>null</tt> if this deque is empty. 2636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2642f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of this deque, or <tt>null</tt> if this deque is empty 2656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E pollFirst(); 2676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2692f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the last element of this deque, 2702f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * or returns <tt>null</tt> if this deque is empty. 2716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2722f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the tail of this deque, or <tt>null</tt> if this deque is empty 2736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E pollLast(); 2756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2772f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the first element of this deque. 2782f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 2792f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * This method differs from {@link #peekFirst peekFirst} only in that it 2802f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * throws an exception if this deque is empty. 2816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2822f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of this deque 2832f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 2846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E getFirst(); 2866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2882f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the last element of this deque. 2892f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * This method differs from {@link #peekLast peekLast} only in that it 2902f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * throws an exception if this deque is empty. 2916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2922f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the tail of this deque 2932f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 2946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E getLast(); 2966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2982f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the first element of this deque, 2992f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * or returns <tt>null</tt> if this deque is empty. 3006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3012f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of this deque, or <tt>null</tt> if this deque is empty 3026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E peekFirst(); 3046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3062f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the last element of this deque, 3072f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * or returns <tt>null</tt> if this deque is empty. 3086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3092f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the tail of this deque, or <tt>null</tt> if this deque is empty 3106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E peekLast(); 3126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3142f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Removes the first occurrence of the specified element from this deque. 3152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * If the deque does not contain the element, it is unchanged. 3162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * More formally, removes the first element <tt>e</tt> such that 3172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>(o==null ? e==null : o.equals(e))</tt> 3182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (if such an element exists). 3192f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns <tt>true</tt> if this deque contained the specified element 3202f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (or equivalently, if this deque changed as a result of the call). 3216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3222f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param o element to be removed from this deque, if present 3232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if an element was removed as a result of this call 3242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 3252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * is incompatible with this deque (optional) 3262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 3272f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements (optional) 3286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean removeFirstOccurrence(Object o); 3306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Removes the last occurrence of the specified element from this deque. 3332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * If the deque does not contain the element, it is unchanged. 3342f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * More formally, removes the last element <tt>e</tt> such that 3352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>(o==null ? e==null : o.equals(e))</tt> 3362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (if such an element exists). 3372f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns <tt>true</tt> if this deque contained the specified element 3382f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (or equivalently, if this deque changed as a result of the call). 3396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3402f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param o element to be removed from this deque, if present 3412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if an element was removed as a result of this call 3422f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 3432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * is incompatible with this deque (optional) 3442f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 3452f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements (optional) 3466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean removeLastOccurrence(Object o); 3486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3492f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson // *** Queue methods *** 3502f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 3512f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 3522f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element into the queue represented by this deque 3532f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (in other words, at the tail of this deque) if it is possible to do so 3542f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * immediately without violating capacity restrictions, returning 3552f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>true</tt> upon success and throwing an 3562f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>IllegalStateException</tt> if no space is currently available. 3572f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * When using a capacity-restricted deque, it is generally preferable to 358a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * use {@link #offer(Object) offer}. 3592f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 3602f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #addLast}. 3612f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 3622f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 3632f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> (as specified by {@link Collection#add}) 3642f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalStateException if the element cannot be added at this 3652f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * time due to capacity restrictions 3662f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 3672f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 3682f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 3692f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 3702f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 3712f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 3722f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 3732f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson boolean add(E e); 3742f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 3752f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 3762f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Inserts the specified element into the queue represented by this deque 3772f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (in other words, at the tail of this deque) if it is possible to do so 3782f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * immediately without violating capacity restrictions, returning 3792f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>true</tt> upon success and <tt>false</tt> if no space is currently 3802f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * available. When using a capacity-restricted deque, this method is 3812f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * generally preferable to the {@link #add} method, which can fail to 3822f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * insert an element only by throwing an exception. 3832f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 3842f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #offerLast}. 3852f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 3862f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to add 3872f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if the element was added to this deque, else 3882f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>false</tt> 3892f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 3902f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 3912f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 3922f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 3932f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 3942f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 3952f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 3962f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson boolean offer(E e); 3972f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 3986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3992f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the head of the queue represented by this deque 4002f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (in other words, the first element of this deque). 4012f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * This method differs from {@link #poll poll} only in that it throws an 4022f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * exception if this deque is empty. 4036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 4042f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #removeFirst()}. 4052f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4062f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of the queue represented by this deque 4072f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 4082f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 4092f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson E remove(); 4102f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4112f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 4122f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves and removes the head of the queue represented by this deque 4132f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (in other words, the first element of this deque), or returns 4142f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>null</tt> if this deque is empty. 4152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #pollFirst()}. 4172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the first element of this deque, or <tt>null</tt> if 4192f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * this deque is empty 4202f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 4212f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson E poll(); 4222f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 4242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the head of the queue represented by 4252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * this deque (in other words, the first element of this deque). 4262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * This method differs from {@link #peek peek} only in that it throws an 4272f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * exception if this deque is empty. 4282f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4292f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #getFirst()}. 4302f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4312f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of the queue represented by this deque 4322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 4332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 4342f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson E element(); 4352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 4372f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Retrieves, but does not remove, the head of the queue represented by 4382f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * this deque (in other words, the first element of this deque), or 4392f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * returns <tt>null</tt> if this deque is empty. 4402f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #peekFirst()}. 4422f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the head of the queue represented by this deque, or 4442f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>null</tt> if this deque is empty 4452f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 4462f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson E peek(); 4472f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4482f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4492f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson // *** Stack methods *** 4502f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4512f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 4522f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Pushes an element onto the stack represented by this deque (in other 4532f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * words, at the head of this deque) if it is possible to do so 4542f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * immediately without violating capacity restrictions, returning 4552f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>true</tt> upon success and throwing an 4562f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>IllegalStateException</tt> if no space is currently available. 4572f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4582f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #addFirst}. 4592f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4602f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param e the element to push 4612f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalStateException if the element cannot be added at this 4622f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * time due to capacity restrictions 4632f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 4642f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * prevents it from being added to this deque 4652f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 4662f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements 4672f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws IllegalArgumentException if some property of the specified 4682f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * element prevents it from being added to this deque 4696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 4706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson void push(E e); 4716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 4726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4732f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Pops an element from the stack represented by this deque. In other 4742f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * words, removes and returns the first element of this deque. 4756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 4762f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #removeFirst()}. 4772f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4782f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the element at the front of this deque (which is the top 4792f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * of the stack represented by this deque) 4802f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NoSuchElementException if this deque is empty 4816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 4826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson E pop(); 4836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 4842f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4852f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson // *** Collection methods *** 4862f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 4876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4882f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Removes the first occurrence of the specified element from this deque. 4892f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * If the deque does not contain the element, it is unchanged. 4902f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * More formally, removes the first element <tt>e</tt> such that 4912f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>(o==null ? e==null : o.equals(e))</tt> 4922f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (if such an element exists). 4932f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns <tt>true</tt> if this deque contained the specified element 4942f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * (or equivalently, if this deque changed as a result of the call). 4952f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 4962f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <p>This method is equivalent to {@link #removeFirstOccurrence}. 4976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 4982f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param o element to be removed from this deque, if present 4992f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if an element was removed as a result of this call 5002f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the class of the specified element 5012f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * is incompatible with this deque (optional) 5022f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 5032f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements (optional) 5042f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 5052f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson boolean remove(Object o); 5062f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 5072f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 5082f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns <tt>true</tt> if this deque contains the specified element. 5092f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * More formally, returns <tt>true</tt> if and only if this deque contains 5102f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * at least one element <tt>e</tt> such that 5112f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * <tt>(o==null ? e==null : o.equals(e))</tt>. 5122f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 5132f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @param o element whose presence in this deque is to be tested 5142f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return <tt>true</tt> if this deque contains the specified element 5152f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws ClassCastException if the type of the specified element 5162f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * is incompatible with this deque (optional) 5172f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @throws NullPointerException if the specified element is null and this 5182f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * deque does not permit null elements (optional) 5192f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 5202f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson boolean contains(Object o); 5212f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 5222f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 5232f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns the number of elements in this deque. 5242f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 5252f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return the number of elements in this deque 5262f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 5272f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson public int size(); 5282f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 5292f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 5302f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns an iterator over the elements in this deque in proper sequence. 5312f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * The elements will be returned in order from first (head) to last (tail). 5322f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 5332f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return an iterator over the elements in this deque in proper sequence 5342f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson */ 5352f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson Iterator<E> iterator(); 5362f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 5372f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson /** 5382f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * Returns an iterator over the elements in this deque in reverse 5392f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * sequential order. The elements will be returned in order from 5402f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * last (tail) to first (head). 5412f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * 5422f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * @return an iterator over the elements in this deque in reverse 5432f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson * sequence 5446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 5456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Iterator<E> descendingIterator(); 5462f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson 5472f03027aaa09158ac70ebf9c6b53f7bb8c495541Jesse Wilson} 548