/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * This file is available under and governed by the GNU General Public * License version 2 only, as published by the Free Software Foundation. * However, the following notice accompanied the original version of this * file: * * Written by Doug Lea and Josh Bloch with assistance from members of JCP * JSR-166 Expert Group and released to the public domain, as explained at * http://creativecommons.org/publicdomain/zero/1.0/ */ package java.util; /** * A {@link SortedMap} extended with navigation methods returning the * closest matches for given search targets. Methods * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry}, * and {@code higherEntry} return {@code Map.Entry} objects * associated with keys respectively less than, less than or equal, * greater than or equal, and greater than a given key, returning * {@code null} if there is no such key.  Similarly, methods * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and * {@code higherKey} return only the associated keys. All of these * methods are designed for locating, not traversing entries. * * <p>A {@code NavigableMap} may be accessed and traversed in either * ascending or descending key order.  The {@code descendingMap} * method returns a view of the map with the senses of all relational * and directional methods inverted. The performance of ascending * operations and views is likely to be faster than that of descending * ones.  Methods {@code subMap}, {@code headMap}, * and {@code tailMap} differ from the like-named {@code * SortedMap} methods in accepting additional arguments describing * whether lower and upper bounds are inclusive versus exclusive. * Submaps of any {@code NavigableMap} must implement the {@code * NavigableMap} interface. * * <p>This interface additionally defines methods {@code firstEntry}, * {@code pollFirstEntry}, {@code lastEntry}, and * {@code pollLastEntry} that return and/or remove the least and * greatest mappings, if any exist, else returning {@code null}. * * <p>Implementations of entry-returning methods are expected to * return {@code Map.Entry} pairs representing snapshots of mappings * at the time they were produced, and thus generally do <em>not</em> * support the optional {@code Entry.setValue} method. Note however * that it is possible to change mappings in the associated map using * method {@code put}. * * <p>Methods * {@link #subMap(Object, Object) subMap(K, K)}, * {@link #headMap(Object) headMap(K)}, and * {@link #tailMap(Object) tailMap(K)} * are specified to return {@code SortedMap} to allow existing * implementations of {@code SortedMap} to be compatibly retrofitted to * implement {@code NavigableMap}, but extensions and implementations * of this interface are encouraged to override these methods to return * {@code NavigableMap}.  Similarly, * {@link #keySet()} can be overriden to return {@code NavigableSet}. * * <p>This interface is a member of the * <a href="{@docRoot}/../technotes/guides/collections/index.html"> * Java Collections Framework</a>. * * @author Doug Lea * @author Josh Bloch * @param <K> the type of keys maintained by this map * @param <V> the type of mapped values * @since 1.6 */public interface NavigableMap<K,V> extends SortedMap<K,V> {    /**     * Returns a key-value mapping associated with the greatest key     * strictly less than the given key, or {@code null} if there is     * no such key.     *     * @param key the key     * @return an entry with the greatest key less than {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    Map.Entry<K,V> lowerEntry(K key);     /**     * Returns the greatest key strictly less than the given key, or     * {@code null} if there is no such key.     *     * @param key the key     * @return the greatest key less than {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    K lowerKey(K key);     /**     * Returns a key-value mapping associated with the greatest key     * less than or equal to the given key, or {@code null} if there     * is no such key.     *     * @param key the key     * @return an entry with the greatest key less than or equal to     *         {@code key}, or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    Map.Entry<K,V> floorEntry(K key);     /**     * Returns the greatest key less than or equal to the given key,     * or {@code null} if there is no such key.     *     * @param key the key     * @return the greatest key less than or equal to {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    K floorKey(K key);     /**     * Returns a key-value mapping associated with the least key     * greater than or equal to the given key, or {@code null} if     * there is no such key.     *     * @param key the key     * @return an entry with the least key greater than or equal to     *         {@code key}, or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    Map.Entry<K,V> ceilingEntry(K key);     /**     * Returns the least key greater than or equal to the given key,     * or {@code null} if there is no such key.     *     * @param key the key     * @return the least key greater than or equal to {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    K ceilingKey(K key);     /**     * Returns a key-value mapping associated with the least key     * strictly greater than the given key, or {@code null} if there     * is no such key.     *     * @param key the key     * @return an entry with the least key greater than {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    Map.Entry<K,V> higherEntry(K key);     /**     * Returns the least key strictly greater than the given key, or     * {@code null} if there is no such key.     *     * @param key the key     * @return the least key greater than {@code key},     *         or {@code null} if there is no such key     * @throws ClassCastException if the specified key cannot be compared     *         with the keys currently in the map     * @throws NullPointerException if the specified key is null     *         and this map does not permit null keys     */    K higherKey(K key);     /**     * Returns a key-value mapping associated with the least     * key in this map, or {@code null} if the map is empty.     *     * @return an entry with the least key,     *         or {@code null} if this map is empty     */    Map.Entry<K,V> firstEntry();     /**     * Returns a key-value mapping associated with the greatest     * key in this map, or {@code null} if the map is empty.     *     * @return an entry with the greatest key,     *         or {@code null} if this map is empty     */    Map.Entry<K,V> lastEntry();     /**     * Removes and returns a key-value mapping associated with     * the least key in this map, or {@code null} if the map is empty.     *     * @return the removed first entry of this map,     *         or {@code null} if this map is empty     */    Map.Entry<K,V> pollFirstEntry();     /**     * Removes and returns a key-value mapping associated with     * the greatest key in this map, or {@code null} if the map is empty.     *     * @return the removed last entry of this map,     *         or {@code null} if this map is empty     */    Map.Entry<K,V> pollLastEntry();     /**     * Returns a reverse order view of the mappings contained in this map.     * The descending map is backed by this map, so changes to the map are     * reflected in the descending map, and vice-versa.  If either map is     * modified while an iteration over a collection view of either map     * is in progress (except through the iterator's own {@code remove}     * operation), the results of the iteration are undefined.     *     * <p>The returned map has an ordering equivalent to     * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.     * The expression {@code m.descendingMap().descendingMap()} returns a     * view of {@code m} essentially equivalent to {@code m}.     *     * @return a reverse order view of this map     */    NavigableMap<K,V> descendingMap();     /**     * Returns a {@link NavigableSet} view of the keys contained in this map.     * The set's iterator returns the keys in ascending order.     * The set is backed by the map, so changes to the map are reflected in     * the set, and vice-versa.  If the map is modified while an iteration     * over the set is in progress (except through the iterator's own {@code     * remove} operation), the results of the iteration are undefined.  The     * set supports element removal, which removes the corresponding mapping     * from the map, via the {@code Iterator.remove}, {@code Set.remove},     * {@code removeAll}, {@code retainAll}, and {@code clear} operations.     * It does not support the {@code add} or {@code addAll} operations.     *     * @return a navigable set view of the keys in this map     */    NavigableSet<K> navigableKeySet();     /**     * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.     * The set's iterator returns the keys in descending order.     * The set is backed by the map, so changes to the map are reflected in     * the set, and vice-versa.  If the map is modified while an iteration     * over the set is in progress (except through the iterator's own {@code     * remove} operation), the results of the iteration are undefined.  The     * set supports element removal, which removes the corresponding mapping     * from the map, via the {@code Iterator.remove}, {@code Set.remove},     * {@code removeAll}, {@code retainAll}, and {@code clear} operations.     * It does not support the {@code add} or {@code addAll} operations.     *     * @return a reverse order navigable set view of the keys in this map     */    NavigableSet<K> descendingKeySet();     /**     * Returns a view of the portion of this map whose keys range from     * {@code fromKey} to {@code toKey}.  If {@code fromKey} and     * {@code toKey} are equal, the returned map is empty unless     * {@code fromInclusive} and {@code toInclusive} are both true.  The     * returned map is backed by this map, so changes in the returned map are     * reflected in this map, and vice-versa.  The returned map supports all     * optional map operations that this map supports.     *     * <p>The returned map will throw an {@code IllegalArgumentException}     * on an attempt to insert a key outside of its range, or to construct a     * submap either of whose endpoints lie outside its range.     *     * @param fromKey low endpoint of the keys in the returned map     * @param fromInclusive {@code true} if the low endpoint     *        is to be included in the returned view     * @param toKey high endpoint of the keys in the returned map     * @param toInclusive {@code true} if the high endpoint     *        is to be included in the returned view     * @return a view of the portion of this map whose keys range from     *         {@code fromKey} to {@code toKey}     * @throws ClassCastException if {@code fromKey} and {@code toKey}     *         cannot be compared to one another using this map's comparator     *         (or, if the map has no comparator, using natural ordering).     *         Implementations may, but are not required to, throw this     *         exception if {@code fromKey} or {@code toKey}     *         cannot be compared to keys currently in the map.     * @throws NullPointerException if {@code fromKey} or {@code toKey}     *         is null and this map does not permit null keys     * @throws IllegalArgumentException if {@code fromKey} is greater than     *         {@code toKey}; or if this map itself has a restricted     *         range, and {@code fromKey} or {@code toKey} lies     *         outside the bounds of the range     */    NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,                             K toKey,   boolean toInclusive);     /**     * Returns a view of the portion of this map whose keys are less than (or     * equal to, if {@code inclusive} is true) {@code toKey}.  The returned     * map is backed by this map, so changes in the returned map are reflected     * in this map, and vice-versa.  The returned map supports all optional     * map operations that this map supports.     *     * <p>The returned map will throw an {@code IllegalArgumentException}     * on an attempt to insert a key outside its range.     *     * @param toKey high endpoint of the keys in the returned map     * @param inclusive {@code true} if the high endpoint     *        is to be included in the returned view     * @return a view of the portion of this map whose keys are less than     *         (or equal to, if {@code inclusive} is true) {@code toKey}     * @throws ClassCastException if {@code toKey} is not compatible     *         with this map's comparator (or, if the map has no comparator,     *         if {@code toKey} does not implement {@link Comparable}).     *         Implementations may, but are not required to, throw this     *         exception if {@code toKey} cannot be compared to keys     *         currently in the map.     * @throws NullPointerException if {@code toKey} is null     *         and this map does not permit null keys     * @throws IllegalArgumentException if this map itself has a     *         restricted range, and {@code toKey} lies outside the     *         bounds of the range     */    NavigableMap<K,V> headMap(K toKey, boolean inclusive);     /**     * Returns a view of the portion of this map whose keys are greater than (or     * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned     * map is backed by this map, so changes in the returned map are reflected     * in this map, and vice-versa.  The returned map supports all optional     * map operations that this map supports.     *     * <p>The returned map will throw an {@code IllegalArgumentException}     * on an attempt to insert a key outside its range.     *     * @param fromKey low endpoint of the keys in the returned map     * @param inclusive {@code true} if the low endpoint     *        is to be included in the returned view     * @return a view of the portion of this map whose keys are greater than     *         (or equal to, if {@code inclusive} is true) {@code fromKey}     * @throws ClassCastException if {@code fromKey} is not compatible     *         with this map's comparator (or, if the map has no comparator,     *         if {@code fromKey} does not implement {@link Comparable}).     *         Implementations may, but are not required to, throw this     *         exception if {@code fromKey} cannot be compared to keys     *         currently in the map.     * @throws NullPointerException if {@code fromKey} is null     *         and this map does not permit null keys     * @throws IllegalArgumentException if this map itself has a     *         restricted range, and {@code fromKey} lies outside the     *         bounds of the range     */    NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);     /**     * {@inheritDoc}     *     * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.     *     * @throws ClassCastException       {@inheritDoc}     * @throws NullPointerException     {@inheritDoc}     * @throws IllegalArgumentException {@inheritDoc}     */    SortedMap<K,V> subMap(K fromKey, K toKey);     /**     * {@inheritDoc}     *     * <p>Equivalent to {@code headMap(toKey, false)}.     *     * @throws ClassCastException       {@inheritDoc}     * @throws NullPointerException     {@inheritDoc}     * @throws IllegalArgumentException {@inheritDoc}     */    SortedMap<K,V> headMap(K toKey);     /**     * {@inheritDoc}     *     * <p>Equivalent to {@code tailMap(fromKey, true)}.     *     * @throws ClassCastException       {@inheritDoc}     * @throws NullPointerException     {@inheritDoc}     * @throws IllegalArgumentException {@inheritDoc}     */    SortedMap<K,V> tailMap(K fromKey);}