libjava/java/util/SortedMap.java

   1 /* SortedMap.java -- A map that makes guarantees about the order of its keys
   2    Copyright (C) 1998, 2001, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.util;
  40
  41 /**
  42  * A map which guarantees its key's iteration order. The entries in the
  43  * map are related by the <i>natural ordering</i> of the keys if they
  44  * are Comparable, or by the provided Comparator.  Additional operations
  45  * take advantage of the sorted nature of the map.
  46  * <p>
  47  *
  48  * All keys entered in the map must be mutually comparable; in other words,
  49  * <code>k1.compareTo(k2)</code> or <code>comparator.compare(k1, k2)</code>
  50  * must not throw a ClassCastException. The ordering must be <i>consistent
  51  * with equals</i> (see {@link Comparator} for this definition), if the
  52  * map is to obey the general contract of the Map interface.  If not,
  53  * the results are well-defined, but probably not what you wanted.
  54  * <p>
  55  *
  56  * It is recommended that all implementing classes provide four constructors:
  57  * 1) one that takes no arguments and builds an empty map sorted by natural
  58  * order of the keys; 2) one that takes a Comparator for the sorting order;
  59  * 3) one that takes a Map and sorts according to the natural order of its
  60  * keys; and 4) one that takes a SortedMap and sorts by the same comparator.
  61  * Unfortunately, the Java language does not provide a way to enforce this.
  62  *
  63  * @author Original author unknown
  64  * @author Eric Blake (ebb9@email.byu.edu)
  65  * @see Map
  66  * @see TreeMap
  67  * @see SortedSet
  68  * @see Comparable
  69  * @see Comparator
  70  * @see Collection
  71  * @see ClassCastException
  72  * @since 1.2
  73  * @status updated to 1.4
  74  */
  75 public interface SortedMap extends Map
  76 {
  77   /**
  78    * Returns the comparator used in sorting this map, or null if it is
  79    * the keys' natural ordering.
  80    *
  81    * @return the sorting comparator
  82    */
  83   Comparator comparator();
  84
  85   /**
  86    * Returns the first (lowest sorted) key in the map.
  87    *
  88    * @return the first key
  89    * @throws NoSuchElementException if this map is empty.
  90    */
  91   Object firstKey();
  92
  93   /**
  94    * Returns a view of the portion of the map strictly less than toKey. The
  95    * view is backed by this map, so changes in one show up in the other.
  96    * The submap supports all optional operations of the original.
  97    * <p>
  98    *
  99    * The returned map throws an IllegalArgumentException any time a key is
 100    * used which is out of the range of toKey. Note that the endpoint, toKey,
 101    * is not included; if you want this value to be included, pass its successor
 102    * object in to toKey.  For example, for Integers, you could request
 103    * <code>headMap(new Integer(limit.intValue() + 1))</code>.
 104    *
 105    * @param toKey the exclusive upper range of the submap
 106    * @return the submap
 107    * @throws ClassCastException if toKey is not comparable to the map contents
 108    * @throws IllegalArgumentException if this is a subMap, and toKey is out
 109    *         of range
 110    * @throws NullPointerException if toKey is null but the map does not allow
 111    *         null keys
 112    */
 113   SortedMap headMap(Object toKey);
 114
 115   /**
 116    * Returns the last (highest sorted) key in the map.
 117    *
 118    * @return the last key
 119    * @throws NoSuchElementException if this map is empty.
 120    */
 121   Object lastKey();
 122
 123   /**
 124    * Returns a view of the portion of the map greater than or equal to
 125    * fromKey, and strictly less than toKey. The view is backed by this map,
 126    * so changes in one show up in the other. The submap supports all
 127    * optional operations of the original.
 128    * <p>
 129    *
 130    * The returned map throws an IllegalArgumentException any time a key is
 131    * used which is out of the range of fromKey and toKey. Note that the
 132    * lower endpoint is included, but the upper is not; if you want to
 133    * change the inclusion or exclusion of an endpoint, pass its successor
 134    * object in instead.  For example, for Integers, you could request
 135    * <code>subMap(new Integer(lowlimit.intValue() + 1),
 136    * new Integer(highlimit.intValue() + 1))</code> to reverse
 137    * the inclusiveness of both endpoints.
 138    *
 139    * @param fromKey the inclusive lower range of the submap
 140    * @param toKey the exclusive upper range of the submap
 141    * @return the submap
 142    * @throws ClassCastException if fromKey or toKey is not comparable to
 143    *         the map contents
 144    * @throws IllegalArgumentException if this is a subMap, and fromKey or
 145    *         toKey is out of range
 146    * @throws NullPointerException if fromKey or toKey is null but the map
 147    *         does not allow null keys
 148    */
 149   SortedMap subMap(Object fromKey, Object toKey);
 150
 151   /**
 152    * Returns a view of the portion of the map greater than or equal to
 153    * fromKey. The view is backed by this map, so changes in one show up
 154    * in the other. The submap supports all optional operations of the original.
 155    * <p>
 156    *
 157    * The returned map throws an IllegalArgumentException any time a key is
 158    * used which is out of the range of fromKey. Note that the endpoint, fromKey, is
 159    * included; if you do not want this value to be included, pass its successor object in
 160    * to fromKey.  For example, for Integers, you could request
 161    * <code>tailMap(new Integer(limit.intValue() + 1))</code>.
 162    *
 163    * @param fromKey the inclusive lower range of the submap
 164    * @return the submap
 165    * @throws ClassCastException if fromKey is not comparable to the map
 166    *         contents
 167    * @throws IllegalArgumentException if this is a subMap, and fromKey is out
 168    *         of range
 169    * @throws NullPointerException if fromKey is null but the map does not allow
 170    *         null keys
 171    */
 172   SortedMap tailMap(Object fromKey);
 173 }