rt/emul/compact/src/main/java/java/util/SortedSet.java
author Jaroslav Tulach <jaroslav.tulach@apidesign.org>
Tue, 26 Feb 2013 16:54:16 +0100
changeset 772 d382dacfd73f
parent 597 emul/compact/src/main/java/java/util/SortedSet.java@ee8a922f4268
permissions -rw-r--r--
Moving modules around so the runtime is under one master pom and can be built without building other modules that are in the repository
     1 /*
     2  * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.  Oracle designates this
     8  * particular file as subject to the "Classpath" exception as provided
     9  * by Oracle in the LICENSE file that accompanied this code.
    10  *
    11  * This code is distributed in the hope that it will be useful, but WITHOUT
    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    14  * version 2 for more details (a copy is included in the LICENSE file that
    15  * accompanied this code).
    16  *
    17  * You should have received a copy of the GNU General Public License version
    18  * 2 along with this work; if not, write to the Free Software Foundation,
    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    20  *
    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    22  * or visit www.oracle.com if you need additional information or have any
    23  * questions.
    24  */
    25 
    26 package java.util;
    27 
    28 /**
    29  * A {@link Set} that further provides a <i>total ordering</i> on its elements.
    30  * The elements are ordered using their {@linkplain Comparable natural
    31  * ordering}, or by a {@link Comparator} typically provided at sorted
    32  * set creation time.  The set's iterator will traverse the set in
    33  * ascending element order. Several additional operations are provided
    34  * to take advantage of the ordering.  (This interface is the set
    35  * analogue of {@link SortedMap}.)
    36  *
    37  * <p>All elements inserted into a sorted set must implement the <tt>Comparable</tt>
    38  * interface (or be accepted by the specified comparator).  Furthermore, all
    39  * such elements must be <i>mutually comparable</i>: <tt>e1.compareTo(e2)</tt>
    40  * (or <tt>comparator.compare(e1, e2)</tt>) must not throw a
    41  * <tt>ClassCastException</tt> for any elements <tt>e1</tt> and <tt>e2</tt> in
    42  * the sorted set.  Attempts to violate this restriction will cause the
    43  * offending method or constructor invocation to throw a
    44  * <tt>ClassCastException</tt>.
    45  *
    46  * <p>Note that the ordering maintained by a sorted set (whether or not an
    47  * explicit comparator is provided) must be <i>consistent with equals</i> if
    48  * the sorted set is to correctly implement the <tt>Set</tt> interface.  (See
    49  * the <tt>Comparable</tt> interface or <tt>Comparator</tt> interface for a
    50  * precise definition of <i>consistent with equals</i>.)  This is so because
    51  * the <tt>Set</tt> interface is defined in terms of the <tt>equals</tt>
    52  * operation, but a sorted set performs all element comparisons using its
    53  * <tt>compareTo</tt> (or <tt>compare</tt>) method, so two elements that are
    54  * deemed equal by this method are, from the standpoint of the sorted set,
    55  * equal.  The behavior of a sorted set <i>is</i> well-defined even if its
    56  * ordering is inconsistent with equals; it just fails to obey the general
    57  * contract of the <tt>Set</tt> interface.
    58  *
    59  * <p>All general-purpose sorted set implementation classes should
    60  * provide four "standard" constructors: 1) A void (no arguments)
    61  * constructor, which creates an empty sorted set sorted according to
    62  * the natural ordering of its elements.  2) A constructor with a
    63  * single argument of type <tt>Comparator</tt>, which creates an empty
    64  * sorted set sorted according to the specified comparator.  3) A
    65  * constructor with a single argument of type <tt>Collection</tt>,
    66  * which creates a new sorted set with the same elements as its
    67  * argument, sorted according to the natural ordering of the elements.
    68  * 4) A constructor with a single argument of type <tt>SortedSet</tt>,
    69  * which creates a new sorted set with the same elements and the same
    70  * ordering as the input sorted set.  There is no way to enforce this
    71  * recommendation, as interfaces cannot contain constructors.
    72  *
    73  * <p>Note: several methods return subsets with restricted ranges.
    74  * Such ranges are <i>half-open</i>, that is, they include their low
    75  * endpoint but not their high endpoint (where applicable).
    76  * If you need a <i>closed range</i> (which includes both endpoints), and
    77  * the element type allows for calculation of the successor of a given
    78  * value, merely request the subrange from <tt>lowEndpoint</tt> to
    79  * <tt>successor(highEndpoint)</tt>.  For example, suppose that <tt>s</tt>
    80  * is a sorted set of strings.  The following idiom obtains a view
    81  * containing all of the strings in <tt>s</tt> from <tt>low</tt> to
    82  * <tt>high</tt>, inclusive:<pre>
    83  *   SortedSet&lt;String&gt; sub = s.subSet(low, high+"\0");</pre>
    84  *
    85  * A similar technique can be used to generate an <i>open range</i> (which
    86  * contains neither endpoint).  The following idiom obtains a view
    87  * containing all of the Strings in <tt>s</tt> from <tt>low</tt> to
    88  * <tt>high</tt>, exclusive:<pre>
    89  *   SortedSet&lt;String&gt; sub = s.subSet(low+"\0", high);</pre>
    90  *
    91  * <p>This interface is a member of the
    92  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
    93  * Java Collections Framework</a>.
    94  *
    95  * @param <E> the type of elements maintained by this set
    96  *
    97  * @author  Josh Bloch
    98  * @see Set
    99  * @see TreeSet
   100  * @see SortedMap
   101  * @see Collection
   102  * @see Comparable
   103  * @see Comparator
   104  * @see ClassCastException
   105  * @since 1.2
   106  */
   107 
   108 public interface SortedSet<E> extends Set<E> {
   109     /**
   110      * Returns the comparator used to order the elements in this set,
   111      * or <tt>null</tt> if this set uses the {@linkplain Comparable
   112      * natural ordering} of its elements.
   113      *
   114      * @return the comparator used to order the elements in this set,
   115      *         or <tt>null</tt> if this set uses the natural ordering
   116      *         of its elements
   117      */
   118     Comparator<? super E> comparator();
   119 
   120     /**
   121      * Returns a view of the portion of this set whose elements range
   122      * from <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
   123      * exclusive.  (If <tt>fromElement</tt> and <tt>toElement</tt> are
   124      * equal, the returned set is empty.)  The returned set is backed
   125      * by this set, so changes in the returned set are reflected in
   126      * this set, and vice-versa.  The returned set supports all
   127      * optional set operations that this set supports.
   128      *
   129      * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
   130      * on an attempt to insert an element outside its range.
   131      *
   132      * @param fromElement low endpoint (inclusive) of the returned set
   133      * @param toElement high endpoint (exclusive) of the returned set
   134      * @return a view of the portion of this set whose elements range from
   135      *         <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive
   136      * @throws ClassCastException if <tt>fromElement</tt> and
   137      *         <tt>toElement</tt> cannot be compared to one another using this
   138      *         set's comparator (or, if the set has no comparator, using
   139      *         natural ordering).  Implementations may, but are not required
   140      *         to, throw this exception if <tt>fromElement</tt> or
   141      *         <tt>toElement</tt> cannot be compared to elements currently in
   142      *         the set.
   143      * @throws NullPointerException if <tt>fromElement</tt> or
   144      *         <tt>toElement</tt> is null and this set does not permit null
   145      *         elements
   146      * @throws IllegalArgumentException if <tt>fromElement</tt> is
   147      *         greater than <tt>toElement</tt>; or if this set itself
   148      *         has a restricted range, and <tt>fromElement</tt> or
   149      *         <tt>toElement</tt> lies outside the bounds of the range
   150      */
   151     SortedSet<E> subSet(E fromElement, E toElement);
   152 
   153     /**
   154      * Returns a view of the portion of this set whose elements are
   155      * strictly less than <tt>toElement</tt>.  The returned set is
   156      * backed by this set, so changes in the returned set are
   157      * reflected in this set, and vice-versa.  The returned set
   158      * supports all optional set operations that this set supports.
   159      *
   160      * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
   161      * on an attempt to insert an element outside its range.
   162      *
   163      * @param toElement high endpoint (exclusive) of the returned set
   164      * @return a view of the portion of this set whose elements are strictly
   165      *         less than <tt>toElement</tt>
   166      * @throws ClassCastException if <tt>toElement</tt> is not compatible
   167      *         with this set's comparator (or, if the set has no comparator,
   168      *         if <tt>toElement</tt> does not implement {@link Comparable}).
   169      *         Implementations may, but are not required to, throw this
   170      *         exception if <tt>toElement</tt> cannot be compared to elements
   171      *         currently in the set.
   172      * @throws NullPointerException if <tt>toElement</tt> is null and
   173      *         this set does not permit null elements
   174      * @throws IllegalArgumentException if this set itself has a
   175      *         restricted range, and <tt>toElement</tt> lies outside the
   176      *         bounds of the range
   177      */
   178     SortedSet<E> headSet(E toElement);
   179 
   180     /**
   181      * Returns a view of the portion of this set whose elements are
   182      * greater than or equal to <tt>fromElement</tt>.  The returned
   183      * set is backed by this set, so changes in the returned set are
   184      * reflected in this set, and vice-versa.  The returned set
   185      * supports all optional set operations that this set supports.
   186      *
   187      * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
   188      * on an attempt to insert an element outside its range.
   189      *
   190      * @param fromElement low endpoint (inclusive) of the returned set
   191      * @return a view of the portion of this set whose elements are greater
   192      *         than or equal to <tt>fromElement</tt>
   193      * @throws ClassCastException if <tt>fromElement</tt> is not compatible
   194      *         with this set's comparator (or, if the set has no comparator,
   195      *         if <tt>fromElement</tt> does not implement {@link Comparable}).
   196      *         Implementations may, but are not required to, throw this
   197      *         exception if <tt>fromElement</tt> cannot be compared to elements
   198      *         currently in the set.
   199      * @throws NullPointerException if <tt>fromElement</tt> is null
   200      *         and this set does not permit null elements
   201      * @throws IllegalArgumentException if this set itself has a
   202      *         restricted range, and <tt>fromElement</tt> lies outside the
   203      *         bounds of the range
   204      */
   205     SortedSet<E> tailSet(E fromElement);
   206 
   207     /**
   208      * Returns the first (lowest) element currently in this set.
   209      *
   210      * @return the first (lowest) element currently in this set
   211      * @throws NoSuchElementException if this set is empty
   212      */
   213     E first();
   214 
   215     /**
   216      * Returns the last (highest) element currently in this set.
   217      *
   218      * @return the last (highest) element currently in this set
   219      * @throws NoSuchElementException if this set is empty
   220      */
   221     E last();
   222 }