libjava/java/util/SortedSet.java

   1 /* SortedSet.java -- A set that makes guarantees about the order of its
   2    elements
   3    Copyright (C) 1998, 2001 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Classpath.
   6
   7 GNU Classpath is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Classpath is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Classpath; see the file COPYING.  If not, write to the
  19 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20 02111-1307 USA.
  21
  22 Linking this library statically or dynamically with other modules is
  23 making a combined work based on this library.  Thus, the terms and
  24 conditions of the GNU General Public License cover the whole
  25 combination.
  26
  27 As a special exception, the copyright holders of this library give you
  28 permission to link this library with independent modules to produce an
  29 executable, regardless of the license terms of these independent
  30 modules, and to copy and distribute the resulting executable under
  31 terms of your choice, provided that you also meet, for each linked
  32 independent module, the terms and conditions of the license of that
  33 module.  An independent module is a module which is not derived from
  34 or based on this library.  If you modify this library, you may extend
  35 this exception to your version of the library, but you are not
  36 obligated to do so.  If you do not wish to do so, delete this
  37 exception statement from your version. */
  38
  39
  40 package java.util;
  41
  42 /**
  43  * A set which guarantees its iteration order. The elements in the set
  44  * are related by the <i>natural ordering</i> if they are Comparable, or
  45  * by the provided Comparator.  Additional operations take advantage of
  46  * the sorted nature of the set.
  47  * <p>
  48  *
  49  * All elements entered in the set must be mutually comparable; in other words,
  50  * <code>k1.compareTo(k2)</code> or <code>comparator.compare(k1, k2)</code>
  51  * must not throw a ClassCastException. The ordering must be <i>consistent
  52  * with equals</i> (see {@link Comparator} for this definition), if the
  53  * map is to obey the general contract of the Set interface.  If not,
  54  * the results are well-defined, but probably not what you wanted.
  55  * <p>
  56  *
  57  * It is recommended that all implementing classes provide four constructors:
  58  * 1) one that takes no arguments and builds an empty set sorted by natural
  59  * order of the elements; 2) one that takes a Comparator for the sorting order;
  60  * 3) one that takes a Set and sorts according to the natural order of its
  61  * elements; and 4) one that takes a SortedSet and sorts by the same
  62  * comparator. Unfortunately, the Java language does not provide a way to
  63  * enforce this.
  64  *
  65  * @author Original author unknown
  66  * @author Eric Blake <ebb9@email.byu.edu>
  67  * @see Set
  68  * @see TreeSet
  69  * @see SortedMap
  70  * @see Collection
  71  * @see Comparable
  72  * @see Comparator
  73  * @see ClassCastException
  74  * @since 1.2
  75  * @status updated to 1.4
  76  */
  77 public interface SortedSet extends Set
  78 {
  79   /**
  80    * Returns the comparator used in sorting this set, or null if it is
  81    * the elements' natural ordering.
  82    *
  83    * @return the sorting comparator
  84    */
  85   Comparator comparator();
  86
  87   /**
  88    * Returns the first (lowest sorted) element in the map.
  89    *
  90    * @return the first element
  91    */
  92   Object first();
  93
  94   /**
  95    * Returns a view of the portion of the set strictly less than toElement. The
  96    * view is backed by this set, so changes in one show up in the other.
  97    * The subset supports all optional operations of the original.
  98    * <p>
  99    *
 100    * The returned set throws an IllegalArgumentException any time an element is
 101    * used which is out of the range of toElement. Note that the endpoint is not
 102    * included; if you want the endpoint, pass the successor object in to
 103    * toElement.  For example, for Strings, you can request
 104    * <code>headSet(limit + "\0")</code>.
 105    *
 106    * @param toElement the exclusive upper range of the subset
 107    * @return the subset
 108    * @throws ClassCastException if toElement is not comparable to the set
 109    *         contents
 110    * @throws IllegalArgumentException if this is a subSet, and toElement is out
 111    *         of range
 112    * @throws NullPointerException if toElement is null but the map does not
 113    *         allow null elements
 114    */
 115   SortedSet headSet(Object toElement);
 116
 117   /**
 118    * Returns the last (highest sorted) element in the map.
 119    *
 120    * @return the last element
 121    */
 122   Object last();
 123
 124   /**
 125    * Returns a view of the portion of the set greater than or equal to
 126    * fromElement, and strictly less than toElement. The view is backed by
 127    * this set, so changes in one show up in the other. The subset supports all
 128    * optional operations of the original.
 129    * <p>
 130    *
 131    * The returned set throws an IllegalArgumentException any time an element is
 132    * used which is out of the range of fromElement and toElement. Note that the
 133    * lower endpoint is included, but the upper is not; if you want to
 134    * change the inclusion or exclusion of an endpoint, pass the successor
 135    * object in instead.  For example, for Strings, you can request
 136    * <code>subSet(lowlimit + "\0", highlimit + "\0")</code> to reverse
 137    * the inclusiveness of both endpoints.
 138    *
 139    * @param fromElement the inclusive lower range of the subset
 140    * @param toElement the exclusive upper range of the subset
 141    * @return the subset
 142    * @throws ClassCastException if fromElement or toElement is not comparable
 143    *         to the set contents
 144    * @throws IllegalArgumentException if this is a subSet, and fromElement or
 145    *         toElement is out of range
 146    * @throws NullPointerException if fromElement or toElement is null but the
 147    *         set does not allow null elements
 148    */
 149   SortedSet subSet(Object fromElement, Object toElement);
 150
 151   /**
 152    * Returns a view of the portion of the set greater than or equal to
 153    * fromElement. The view is backed by this set, so changes in one show up
 154    * in the other. The subset supports all optional operations of the original.
 155    * <p>
 156    *
 157    * The returned set throws an IllegalArgumentException any time an element is
 158    * used which is out of the range of fromElement. Note that the endpoint is
 159    * included; if you do not want the endpoint, pass the successor object in
 160    * to fromElement.  For example, for Strings, you can request
 161    * <code>tailSet(limit + "\0")</code>.
 162    *
 163    * @param fromElement the inclusive lower range of the subset
 164    * @return the subset
 165    * @throws ClassCastException if fromElement is not comparable to the set
 166    *         contents
 167    * @throws IllegalArgumentException if this is a subSet, and fromElement is
 168    *         out of range
 169    * @throws NullPointerException if fromElement is null but the set does not
 170    *         allow null elements
 171    */
 172   SortedSet tailSet(Object fromElement);
 173 }