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    1   /*
    2    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    3    *
    4    * This code is free software; you can redistribute it and/or modify it
    5    * under the terms of the GNU General Public License version 2 only, as
    6    * published by the Free Software Foundation.  Oracle designates this
    7    * particular file as subject to the "Classpath" exception as provided
    8    * by Oracle in the LICENSE file that accompanied this code.
    9    *
   10    * This code is distributed in the hope that it will be useful, but WITHOUT
   11    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   12    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   13    * version 2 for more details (a copy is included in the LICENSE file that
   14    * accompanied this code).
   15    *
   16    * You should have received a copy of the GNU General Public License version
   17    * 2 along with this work; if not, write to the Free Software Foundation,
   18    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   19    *
   20    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   21    * or visit www.oracle.com if you need additional information or have any
   22    * questions.
   23    */
   24   
   25   /*
   26    * This file is available under and governed by the GNU General Public
   27    * License version 2 only, as published by the Free Software Foundation.
   28    * However, the following notice accompanied the original version of this
   29    * file:
   30    *
   31    * Written by Doug Lea and Josh Bloch with assistance from members of JCP
   32    * JSR-166 Expert Group and released to the public domain, as explained at
   33    * http://creativecommons.org/publicdomain/zero/1.0/
   34    */
   35   
   36   package java.util;
   37   
   38   /**
   39    * A {@link SortedMap} extended with navigation methods returning the
   40    * closest matches for given search targets. Methods
   41    * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
   42    * and {@code higherEntry} return {@code Map.Entry} objects
   43    * associated with keys respectively less than, less than or equal,
   44    * greater than or equal, and greater than a given key, returning
   45    * {@code null} if there is no such key.  Similarly, methods
   46    * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
   47    * {@code higherKey} return only the associated keys. All of these
   48    * methods are designed for locating, not traversing entries.
   49    *
   50    * <p>A {@code NavigableMap} may be accessed and traversed in either
   51    * ascending or descending key order.  The {@code descendingMap}
   52    * method returns a view of the map with the senses of all relational
   53    * and directional methods inverted. The performance of ascending
   54    * operations and views is likely to be faster than that of descending
   55    * ones.  Methods {@code subMap}, {@code headMap},
   56    * and {@code tailMap} differ from the like-named {@code
   57    * SortedMap} methods in accepting additional arguments describing
   58    * whether lower and upper bounds are inclusive versus exclusive.
   59    * Submaps of any {@code NavigableMap} must implement the {@code
   60    * NavigableMap} interface.
   61    *
   62    * <p>This interface additionally defines methods {@code firstEntry},
   63    * {@code pollFirstEntry}, {@code lastEntry}, and
   64    * {@code pollLastEntry} that return and/or remove the least and
   65    * greatest mappings, if any exist, else returning {@code null}.
   66    *
   67    * <p>Implementations of entry-returning methods are expected to
   68    * return {@code Map.Entry} pairs representing snapshots of mappings
   69    * at the time they were produced, and thus generally do <em>not</em>
   70    * support the optional {@code Entry.setValue} method. Note however
   71    * that it is possible to change mappings in the associated map using
   72    * method {@code put}.
   73    *
   74    * <p>Methods
   75    * {@link #subMap(Object, Object) subMap(K, K)},
   76    * {@link #headMap(Object) headMap(K)}, and
   77    * {@link #tailMap(Object) tailMap(K)}
   78    * are specified to return {@code SortedMap} to allow existing
   79    * implementations of {@code SortedMap} to be compatibly retrofitted to
   80    * implement {@code NavigableMap}, but extensions and implementations
   81    * of this interface are encouraged to override these methods to return
   82    * {@code NavigableMap}.  Similarly,
   83    * {@link #keySet()} can be overriden to return {@code NavigableSet}.
   84    *
   85    * <p>This interface is a member of the
   86    * <a href="{@docRoot}/../technotes/guides/collections/index.html">
   87    * Java Collections Framework</a>.
   88    *
   89    * @author Doug Lea
   90    * @author Josh Bloch
   91    * @param <K> the type of keys maintained by this map
   92    * @param <V> the type of mapped values
   93    * @since 1.6
   94    */
   95   public interface NavigableMap<K,V> extends SortedMap<K,V> {
   96       /**
   97        * Returns a key-value mapping associated with the greatest key
   98        * strictly less than the given key, or {@code null} if there is
   99        * no such key.
  100        *
  101        * @param key the key
  102        * @return an entry with the greatest key less than {@code key},
  103        *         or {@code null} if there is no such key
  104        * @throws ClassCastException if the specified key cannot be compared
  105        *         with the keys currently in the map
  106        * @throws NullPointerException if the specified key is null
  107        *         and this map does not permit null keys
  108        */
  109       Map.Entry<K,V> lowerEntry(K key);
  110   
  111       /**
  112        * Returns the greatest key strictly less than the given key, or
  113        * {@code null} if there is no such key.
  114        *
  115        * @param key the key
  116        * @return the greatest key less than {@code key},
  117        *         or {@code null} if there is no such key
  118        * @throws ClassCastException if the specified key cannot be compared
  119        *         with the keys currently in the map
  120        * @throws NullPointerException if the specified key is null
  121        *         and this map does not permit null keys
  122        */
  123       K lowerKey(K key);
  124   
  125       /**
  126        * Returns a key-value mapping associated with the greatest key
  127        * less than or equal to the given key, or {@code null} if there
  128        * is no such key.
  129        *
  130        * @param key the key
  131        * @return an entry with the greatest key less than or equal to
  132        *         {@code key}, or {@code null} if there is no such key
  133        * @throws ClassCastException if the specified key cannot be compared
  134        *         with the keys currently in the map
  135        * @throws NullPointerException if the specified key is null
  136        *         and this map does not permit null keys
  137        */
  138       Map.Entry<K,V> floorEntry(K key);
  139   
  140       /**
  141        * Returns the greatest key less than or equal to the given key,
  142        * or {@code null} if there is no such key.
  143        *
  144        * @param key the key
  145        * @return the greatest key less than or equal to {@code key},
  146        *         or {@code null} if there is no such key
  147        * @throws ClassCastException if the specified key cannot be compared
  148        *         with the keys currently in the map
  149        * @throws NullPointerException if the specified key is null
  150        *         and this map does not permit null keys
  151        */
  152       K floorKey(K key);
  153   
  154       /**
  155        * Returns a key-value mapping associated with the least key
  156        * greater than or equal to the given key, or {@code null} if
  157        * there is no such key.
  158        *
  159        * @param key the key
  160        * @return an entry with the least key greater than or equal to
  161        *         {@code key}, or {@code null} if there is no such key
  162        * @throws ClassCastException if the specified key cannot be compared
  163        *         with the keys currently in the map
  164        * @throws NullPointerException if the specified key is null
  165        *         and this map does not permit null keys
  166        */
  167       Map.Entry<K,V> ceilingEntry(K key);
  168   
  169       /**
  170        * Returns the least key greater than or equal to the given key,
  171        * or {@code null} if there is no such key.
  172        *
  173        * @param key the key
  174        * @return the least key greater than or equal to {@code key},
  175        *         or {@code null} if there is no such key
  176        * @throws ClassCastException if the specified key cannot be compared
  177        *         with the keys currently in the map
  178        * @throws NullPointerException if the specified key is null
  179        *         and this map does not permit null keys
  180        */
  181       K ceilingKey(K key);
  182   
  183       /**
  184        * Returns a key-value mapping associated with the least key
  185        * strictly greater than the given key, or {@code null} if there
  186        * is no such key.
  187        *
  188        * @param key the key
  189        * @return an entry with the least key greater than {@code key},
  190        *         or {@code null} if there is no such key
  191        * @throws ClassCastException if the specified key cannot be compared
  192        *         with the keys currently in the map
  193        * @throws NullPointerException if the specified key is null
  194        *         and this map does not permit null keys
  195        */
  196       Map.Entry<K,V> higherEntry(K key);
  197   
  198       /**
  199        * Returns the least key strictly greater than the given key, or
  200        * {@code null} if there is no such key.
  201        *
  202        * @param key the key
  203        * @return the least key greater than {@code key},
  204        *         or {@code null} if there is no such key
  205        * @throws ClassCastException if the specified key cannot be compared
  206        *         with the keys currently in the map
  207        * @throws NullPointerException if the specified key is null
  208        *         and this map does not permit null keys
  209        */
  210       K higherKey(K key);
  211   
  212       /**
  213        * Returns a key-value mapping associated with the least
  214        * key in this map, or {@code null} if the map is empty.
  215        *
  216        * @return an entry with the least key,
  217        *         or {@code null} if this map is empty
  218        */
  219       Map.Entry<K,V> firstEntry();
  220   
  221       /**
  222        * Returns a key-value mapping associated with the greatest
  223        * key in this map, or {@code null} if the map is empty.
  224        *
  225        * @return an entry with the greatest key,
  226        *         or {@code null} if this map is empty
  227        */
  228       Map.Entry<K,V> lastEntry();
  229   
  230       /**
  231        * Removes and returns a key-value mapping associated with
  232        * the least key in this map, or {@code null} if the map is empty.
  233        *
  234        * @return the removed first entry of this map,
  235        *         or {@code null} if this map is empty
  236        */
  237       Map.Entry<K,V> pollFirstEntry();
  238   
  239       /**
  240        * Removes and returns a key-value mapping associated with
  241        * the greatest key in this map, or {@code null} if the map is empty.
  242        *
  243        * @return the removed last entry of this map,
  244        *         or {@code null} if this map is empty
  245        */
  246       Map.Entry<K,V> pollLastEntry();
  247   
  248       /**
  249        * Returns a reverse order view of the mappings contained in this map.
  250        * The descending map is backed by this map, so changes to the map are
  251        * reflected in the descending map, and vice-versa.  If either map is
  252        * modified while an iteration over a collection view of either map
  253        * is in progress (except through the iterator's own {@code remove}
  254        * operation), the results of the iteration are undefined.
  255        *
  256        * <p>The returned map has an ordering equivalent to
  257        * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
  258        * The expression {@code m.descendingMap().descendingMap()} returns a
  259        * view of {@code m} essentially equivalent to {@code m}.
  260        *
  261        * @return a reverse order view of this map
  262        */
  263       NavigableMap<K,V> descendingMap();
  264   
  265       /**
  266        * Returns a {@link NavigableSet} view of the keys contained in this map.
  267        * The set's iterator returns the keys in ascending order.
  268        * The set is backed by the map, so changes to the map are reflected in
  269        * the set, and vice-versa.  If the map is modified while an iteration
  270        * over the set is in progress (except through the iterator's own {@code
  271        * remove} operation), the results of the iteration are undefined.  The
  272        * set supports element removal, which removes the corresponding mapping
  273        * from the map, via the {@code Iterator.remove}, {@code Set.remove},
  274        * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
  275        * It does not support the {@code add} or {@code addAll} operations.
  276        *
  277        * @return a navigable set view of the keys in this map
  278        */
  279       NavigableSet<K> navigableKeySet();
  280   
  281       /**
  282        * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.
  283        * The set's iterator returns the keys in descending order.
  284        * The set is backed by the map, so changes to the map are reflected in
  285        * the set, and vice-versa.  If the map is modified while an iteration
  286        * over the set is in progress (except through the iterator's own {@code
  287        * remove} operation), the results of the iteration are undefined.  The
  288        * set supports element removal, which removes the corresponding mapping
  289        * from the map, via the {@code Iterator.remove}, {@code Set.remove},
  290        * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
  291        * It does not support the {@code add} or {@code addAll} operations.
  292        *
  293        * @return a reverse order navigable set view of the keys in this map
  294        */
  295       NavigableSet<K> descendingKeySet();
  296   
  297       /**
  298        * Returns a view of the portion of this map whose keys range from
  299        * {@code fromKey} to {@code toKey}.  If {@code fromKey} and
  300        * {@code toKey} are equal, the returned map is empty unless
  301        * {@code fromInclusive} and {@code toInclusive} are both true.  The
  302        * returned map is backed by this map, so changes in the returned map are
  303        * reflected in this map, and vice-versa.  The returned map supports all
  304        * optional map operations that this map supports.
  305        *
  306        * <p>The returned map will throw an {@code IllegalArgumentException}
  307        * on an attempt to insert a key outside of its range, or to construct a
  308        * submap either of whose endpoints lie outside its range.
  309        *
  310        * @param fromKey low endpoint of the keys in the returned map
  311        * @param fromInclusive {@code true} if the low endpoint
  312        *        is to be included in the returned view
  313        * @param toKey high endpoint of the keys in the returned map
  314        * @param toInclusive {@code true} if the high endpoint
  315        *        is to be included in the returned view
  316        * @return a view of the portion of this map whose keys range from
  317        *         {@code fromKey} to {@code toKey}
  318        * @throws ClassCastException if {@code fromKey} and {@code toKey}
  319        *         cannot be compared to one another using this map's comparator
  320        *         (or, if the map has no comparator, using natural ordering).
  321        *         Implementations may, but are not required to, throw this
  322        *         exception if {@code fromKey} or {@code toKey}
  323        *         cannot be compared to keys currently in the map.
  324        * @throws NullPointerException if {@code fromKey} or {@code toKey}
  325        *         is null and this map does not permit null keys
  326        * @throws IllegalArgumentException if {@code fromKey} is greater than
  327        *         {@code toKey}; or if this map itself has a restricted
  328        *         range, and {@code fromKey} or {@code toKey} lies
  329        *         outside the bounds of the range
  330        */
  331       NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,
  332                                K toKey,   boolean toInclusive);
  333   
  334       /**
  335        * Returns a view of the portion of this map whose keys are less than (or
  336        * equal to, if {@code inclusive} is true) {@code toKey}.  The returned
  337        * map is backed by this map, so changes in the returned map are reflected
  338        * in this map, and vice-versa.  The returned map supports all optional
  339        * map operations that this map supports.
  340        *
  341        * <p>The returned map will throw an {@code IllegalArgumentException}
  342        * on an attempt to insert a key outside its range.
  343        *
  344        * @param toKey high endpoint of the keys in the returned map
  345        * @param inclusive {@code true} if the high endpoint
  346        *        is to be included in the returned view
  347        * @return a view of the portion of this map whose keys are less than
  348        *         (or equal to, if {@code inclusive} is true) {@code toKey}
  349        * @throws ClassCastException if {@code toKey} is not compatible
  350        *         with this map's comparator (or, if the map has no comparator,
  351        *         if {@code toKey} does not implement {@link Comparable}).
  352        *         Implementations may, but are not required to, throw this
  353        *         exception if {@code toKey} cannot be compared to keys
  354        *         currently in the map.
  355        * @throws NullPointerException if {@code toKey} is null
  356        *         and this map does not permit null keys
  357        * @throws IllegalArgumentException if this map itself has a
  358        *         restricted range, and {@code toKey} lies outside the
  359        *         bounds of the range
  360        */
  361       NavigableMap<K,V> headMap(K toKey, boolean inclusive);
  362   
  363       /**
  364        * Returns a view of the portion of this map whose keys are greater than (or
  365        * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned
  366        * map is backed by this map, so changes in the returned map are reflected
  367        * in this map, and vice-versa.  The returned map supports all optional
  368        * map operations that this map supports.
  369        *
  370        * <p>The returned map will throw an {@code IllegalArgumentException}
  371        * on an attempt to insert a key outside its range.
  372        *
  373        * @param fromKey low endpoint of the keys in the returned map
  374        * @param inclusive {@code true} if the low endpoint
  375        *        is to be included in the returned view
  376        * @return a view of the portion of this map whose keys are greater than
  377        *         (or equal to, if {@code inclusive} is true) {@code fromKey}
  378        * @throws ClassCastException if {@code fromKey} is not compatible
  379        *         with this map's comparator (or, if the map has no comparator,
  380        *         if {@code fromKey} does not implement {@link Comparable}).
  381        *         Implementations may, but are not required to, throw this
  382        *         exception if {@code fromKey} cannot be compared to keys
  383        *         currently in the map.
  384        * @throws NullPointerException if {@code fromKey} is null
  385        *         and this map does not permit null keys
  386        * @throws IllegalArgumentException if this map itself has a
  387        *         restricted range, and {@code fromKey} lies outside the
  388        *         bounds of the range
  389        */
  390       NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);
  391   
  392       /**
  393        * {@inheritDoc}
  394        *
  395        * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.
  396        *
  397        * @throws ClassCastException       {@inheritDoc}
  398        * @throws NullPointerException     {@inheritDoc}
  399        * @throws IllegalArgumentException {@inheritDoc}
  400        */
  401       SortedMap<K,V> subMap(K fromKey, K toKey);
  402   
  403       /**
  404        * {@inheritDoc}
  405        *
  406        * <p>Equivalent to {@code headMap(toKey, false)}.
  407        *
  408        * @throws ClassCastException       {@inheritDoc}
  409        * @throws NullPointerException     {@inheritDoc}
  410        * @throws IllegalArgumentException {@inheritDoc}
  411        */
  412       SortedMap<K,V> headMap(K toKey);
  413   
  414       /**
  415        * {@inheritDoc}
  416        *
  417        * <p>Equivalent to {@code tailMap(fromKey, true)}.
  418        *
  419        * @throws ClassCastException       {@inheritDoc}
  420        * @throws NullPointerException     {@inheritDoc}
  421        * @throws IllegalArgumentException {@inheritDoc}
  422        */
  423       SortedMap<K,V> tailMap(K fromKey);
  424   }

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