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	/*
	* Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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	* This code is free software; you can redistribute it and/or modify it
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	* published by the Free Software Foundation. Oracle designates this
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	* 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
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	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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	package java.util;

	/**
	* A {@link Map} that further provides a <em>total ordering</em> on its keys.
	* The map is ordered according to the {@linkplain Comparable natural
	* ordering} of its keys, or by a {@link Comparator} typically
	* provided at sorted map creation time. This order is reflected when
	* iterating over the sorted map's collection views (returned by the
	* {@code entrySet}, {@code keySet} and {@code values} methods).
	* Several additional operations are provided to take advantage of the
	* ordering. (This interface is the map analogue of {@link SortedSet}.)
	*
	* <p>All keys inserted into a sorted map must implement the {@code Comparable}
	* interface (or be accepted by the specified comparator). Furthermore, all
	* such keys must be <em>mutually comparable</em>: {@code k1.compareTo(k2)} (or
	* {@code comparator.compare(k1, k2)}) must not throw a
	* {@code ClassCastException} for any keys {@code k1} and {@code k2} in
	* the sorted map. Attempts to violate this restriction will cause the
	* offending method or constructor invocation to throw a
	* {@code ClassCastException}.
	*
	* <p>Note that the ordering maintained by a sorted map (whether or not an
	* explicit comparator is provided) must be <em>consistent with equals</em> if
	* the sorted map is to correctly implement the {@code Map} interface. (See
	* the {@code Comparable} interface or {@code Comparator} interface for a
	* precise definition of <em>consistent with equals</em>.) This is so because
	* the {@code Map} interface is defined in terms of the {@code equals}
	* operation, but a sorted map performs all key comparisons using its
	* {@code compareTo} (or {@code compare}) method, so two keys that are
	* deemed equal by this method are, from the standpoint of the sorted map,
	* equal. The behavior of a tree map <em>is</em> well-defined even if its
	* ordering is inconsistent with equals; it just fails to obey the general
	* contract of the {@code Map} interface.
	*
	* <p>All general-purpose sorted map implementation classes should provide four
	* "standard" constructors. It is not possible to enforce this recommendation
	* though as required constructors cannot be specified by interfaces. The
	* expected "standard" constructors for all sorted map implementations are:
	* <ol>
	* <li>A void (no arguments) constructor, which creates an empty sorted map
	* sorted according to the natural ordering of its keys.</li>
	* <li>A constructor with a single argument of type {@code Comparator}, which
	* creates an empty sorted map sorted according to the specified comparator.</li>
	* <li>A constructor with a single argument of type {@code Map}, which creates
	* a new map with the same key-value mappings as its argument, sorted
	* according to the keys' natural ordering.</li>
	* <li>A constructor with a single argument of type {@code SortedMap}, which
	* creates a new sorted map with the same key-value mappings and the same
	* ordering as the input sorted map.</li>
	* </ol>
	*
	* <p><strong>Note</strong>: several methods return submaps with restricted key
	* ranges. Such ranges are <em>half-open</em>, that is, they include their low
	* endpoint but not their high endpoint (where applicable). If you need a
	* <em>closed range</em> (which includes both endpoints), and the key type
	* allows for calculation of the successor of a given key, merely request
	* the subrange from {@code lowEndpoint} to
	* {@code successor(highEndpoint)}. For example, suppose that {@code m}
	* is a map whose keys are strings. The following idiom obtains a view
	* containing all of the key-value mappings in {@code m} whose keys are
	* between {@code low} and {@code high}, inclusive:<pre>
	* SortedMap<String, V> sub = m.subMap(low, high+"\0");</pre>
	*
	* A similar technique can be used to generate an <em>open range</em>
	* (which contains neither endpoint). The following idiom obtains a
	* view containing all of the key-value mappings in {@code m} whose keys
	* are between {@code low} and {@code high}, exclusive:<pre>
	* SortedMap<String, V> sub = m.subMap(low+"\0", high);</pre>
	*
	* <p>This interface is a member of the
	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
	* Java Collections Framework</a>.
	*
	* @param <K> the type of keys maintained by this map
	* @param <V> the type of mapped values
	*
	* @author Josh Bloch
	* @see Map
	* @see TreeMap
	* @see SortedSet
	* @see Comparator
	* @see Comparable
	* @see Collection
	* @see ClassCastException
	* @since 1.2
	*/

	public interface SortedMap<K,V> extends Map<K,V> {
	/**
	* Returns the comparator used to order the keys in this map, or
	* {@code null} if this map uses the {@linkplain Comparable
	* natural ordering} of its keys.
	*
	* @return the comparator used to order the keys in this map,
	* or {@code null} if this map uses the natural ordering
	* of its keys
	*/
	Comparator<? super K> comparator();

	/**
	* Returns a view of the portion of this map whose keys range from
	* {@code fromKey}, inclusive, to {@code toKey}, exclusive. (If
	* {@code fromKey} and {@code toKey} are equal, the returned map
	* is empty.) 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 (inclusive) of the keys in the returned map
	* @param toKey high endpoint (exclusive) of the keys in the returned map
	* @return a view of the portion of this map whose keys range from
	* {@code fromKey}, inclusive, to {@code toKey}, exclusive
	* @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
	*/
	SortedMap<K,V> subMap(K fromKey, K toKey);

	/**
	* Returns a view of the portion of this map whose keys are
	* strictly less than {@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 (exclusive) of the keys in the returned map
	* @return a view of the portion of this map whose keys are strictly
	* less than {@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
	*/
	SortedMap<K,V> headMap(K toKey);

	/**
	* Returns a view of the portion of this map whose keys are
	* greater than or equal to {@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 (inclusive) of the keys in the returned map
	* @return a view of the portion of this map whose keys are greater
	* than or equal to {@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
	*/
	SortedMap<K,V> tailMap(K fromKey);

	/**
	* Returns the first (lowest) key currently in this map.
	*
	* @return the first (lowest) key currently in this map
	* @throws NoSuchElementException if this map is empty
	*/
	K firstKey();

	/**
	* Returns the last (highest) key currently in this map.
	*
	* @return the last (highest) key currently in this map
	* @throws NoSuchElementException if this map is empty
	*/
	K lastKey();

	/**
	* Returns a {@link Set} 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 set view of the keys contained in this map, sorted in
	* ascending order
	*/
	Set<K> keySet();

	/**
	* Returns a {@link Collection} view of the values contained in this map.
	* The collection's iterator returns the values in ascending order
	* of the corresponding keys.
	* The collection is backed by the map, so changes to the map are
	* reflected in the collection, and vice-versa. If the map is
	* modified while an iteration over the collection is in progress
	* (except through the iterator's own {@code remove} operation),
	* the results of the iteration are undefined. The collection
	* supports element removal, which removes the corresponding
	* mapping from the map, via the {@code Iterator.remove},
	* {@code Collection.remove}, {@code removeAll},
	* {@code retainAll} and {@code clear} operations. It does not
	* support the {@code add} or {@code addAll} operations.
	*
	* @return a collection view of the values contained in this map,
	* sorted in ascending key order
	*/
	Collection<V> values();

	/**
	* Returns a {@link Set} view of the mappings contained in this map.
	* The set's iterator returns the entries in ascending key 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, or through the
	* {@code setValue} operation on a map entry returned by the
	* iterator) 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 set view of the mappings contained in this map,
	* sorted in ascending key order
	*/
	Set<Map.Entry<K, V>> entrySet();
	}

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