java/util/NavigableSet.java

/*
 * 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 SortedSet} extended with navigation methods reporting
 * closest matches for given search targets. Methods {@code lower},
 * {@code floor}, {@code ceiling}, and {@code higher} return elements
 * respectively less than, less than or equal, greater than or equal,
 * and greater than a given element, returning {@code null} if there
 * is no such element.  A {@code NavigableSet} may be accessed and
 * traversed in either ascending or descending order.  The {@code
 * descendingSet} method returns a view of the set 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.  This interface additionally defines methods
 * {@code pollFirst} and {@code pollLast} that return and remove the
 * lowest and highest element, if one exists, else returning {@code
 * null}.  Methods {@code subSet}, {@code headSet},
 * and {@code tailSet} differ from the like-named {@code
 * SortedSet} methods in accepting additional arguments describing
 * whether lower and upper bounds are inclusive versus exclusive.
 * Subsets of any {@code NavigableSet} must implement the {@code
 * NavigableSet} interface.
 *
 * <p>The return values of navigation methods may be ambiguous in
 * implementations that permit {@code null} elements. However, even
 * in this case the result can be disambiguated by checking
 * {@code contains(null)}. To avoid such issues, implementations of
 * this interface are encouraged to <em>not</em> permit insertion of
 * {@code null} elements. (Note that sorted sets of {@link
 * Comparable} elements intrinsically do not permit {@code null}.)
 *
 * <p>Methods
 * {@link #subSet(Object, Object) subSet(E, E)},
 * {@link #headSet(Object) headSet(E)}, and
 * {@link #tailSet(Object) tailSet(E)}
 * are specified to return {@code SortedSet} to allow existing
 * implementations of {@code SortedSet} to be compatibly retrofitted to
 * implement {@code NavigableSet}, but extensions and implementations
 * of this interface are encouraged to override these methods 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 <E> the type of elements maintained by this set
 * @since 1.6
 */
public interface NavigableSet<E> extends SortedSet<E> {
    /**
     * Returns the greatest element in this set strictly less than the
     * given element, or {@code null} if there is no such element.
     *
     * @param e the value to match
     * @return the greatest element less than {@code e},
     *         or {@code null} if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E lower(E e);

    /**
     * Returns the greatest element in this set less than or equal to
     * the given element, or {@code null} if there is no such element.
     *
     * @param e the value to match
     * @return the greatest element less than or equal to {@code e},
     *         or {@code null} if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E floor(E e);

    /**
     * Returns the least element in this set greater than or equal to
     * the given element, or {@code null} if there is no such element.
     *
     * @param e the value to match
     * @return the least element greater than or equal to {@code e},
     *         or {@code null} if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E ceiling(E e);

    /**
     * Returns the least element in this set strictly greater than the
     * given element, or {@code null} if there is no such element.
     *
     * @param e the value to match
     * @return the least element greater than {@code e},
     *         or {@code null} if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E higher(E e);

    /**
     * Retrieves and removes the first (lowest) element,
     * or returns {@code null} if this set is empty.
     *
     * @return the first element, or {@code null} if this set is empty
     */
    E pollFirst();

    /**
     * Retrieves and removes the last (highest) element,
     * or returns {@code null} if this set is empty.
     *
     * @return the last element, or {@code null} if this set is empty
     */
    E pollLast();

    /**
     * Returns an iterator over the elements in this set, in ascending order.
     *
     * @return an iterator over the elements in this set, in ascending order
     */
    Iterator<E> iterator();

    /**
     * Returns a reverse order view of the elements contained in this set.
     * The descending set is backed by this set, so changes to the set are
     * reflected in the descending set, and vice-versa.  If either set is
     * modified while an iteration over either set is in progress (except
     * through the iterator's own {@code remove} operation), the results of
     * the iteration are undefined.
     *
     * <p>The returned set has an ordering equivalent to
     * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
     * The expression {@code s.descendingSet().descendingSet()} returns a
     * view of {@code s} essentially equivalent to {@code s}.
     *
     * @return a reverse order view of this set
     */
    NavigableSet<E> descendingSet();

    /**
     * Returns an iterator over the elements in this set, in descending order.
     * Equivalent in effect to {@code descendingSet().iterator()}.
     *
     * @return an iterator over the elements in this set, in descending order
     */
    Iterator<E> descendingIterator();

    /**
     * Returns a view of the portion of this set whose elements range from
     * {@code fromElement} to {@code toElement}.  If {@code fromElement} and
     * {@code toElement} are equal, the returned set is empty unless {@code
     * fromExclusive} and {@code toExclusive} are both true.  The returned set
     * is backed by this set, so changes in the returned set are reflected in
     * this set, and vice-versa.  The returned set supports all optional set
     * operations that this set supports.
     *
     * <p>The returned set will throw an {@code IllegalArgumentException}
     * on an attempt to insert an element outside its range.
     *
     * @param fromElement low endpoint of the returned set
     * @param fromInclusive {@code true} if the low endpoint
     *        is to be included in the returned view
     * @param toElement high endpoint of the returned set
     * @param toInclusive {@code true} if the high endpoint
     *        is to be included in the returned view
     * @return a view of the portion of this set whose elements range from
     *         {@code fromElement}, inclusive, to {@code toElement}, exclusive
     * @throws ClassCastException if {@code fromElement} and
     *         {@code toElement} cannot be compared to one another using this
     *         set's comparator (or, if the set has no comparator, using
     *         natural ordering).  Implementations may, but are not required
     *         to, throw this exception if {@code fromElement} or
     *         {@code toElement} cannot be compared to elements currently in
     *         the set.
     * @throws NullPointerException if {@code fromElement} or
     *         {@code toElement} is null and this set does
     *         not permit null elements
     * @throws IllegalArgumentException if {@code fromElement} is
     *         greater than {@code toElement}; or if this set itself
     *         has a restricted range, and {@code fromElement} or
     *         {@code toElement} lies outside the bounds of the range.
     */
    NavigableSet<E> subSet(E fromElement, boolean fromInclusive,
                           E toElement,   boolean toInclusive);

    /**
     * Returns a view of the portion of this set whose elements are less than
     * (or equal to, if {@code inclusive} is true) {@code toElement}.  The
     * returned set is backed by this set, so changes in the returned set are
     * reflected in this set, and vice-versa.  The returned set supports all
     * optional set operations that this set supports.
     *
     * <p>The returned set will throw an {@code IllegalArgumentException}
     * on an attempt to insert an element outside its range.
     *
     * @param toElement high endpoint of the returned set
     * @param inclusive {@code true} if the high endpoint
     *        is to be included in the returned view
     * @return a view of the portion of this set whose elements are less than
     *         (or equal to, if {@code inclusive} is true) {@code toElement}
     * @throws ClassCastException if {@code toElement} is not compatible
     *         with this set's comparator (or, if the set has no comparator,
     *         if {@code toElement} does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if {@code toElement} cannot be compared to elements
     *         currently in the set.
     * @throws NullPointerException if {@code toElement} is null and
     *         this set does not permit null elements
     * @throws IllegalArgumentException if this set itself has a
     *         restricted range, and {@code toElement} lies outside the
     *         bounds of the range
     */
    NavigableSet<E> headSet(E toElement, boolean inclusive);

    /**
     * Returns a view of the portion of this set whose elements are greater
     * than (or equal to, if {@code inclusive} is true) {@code fromElement}.
     * The returned set is backed by this set, so changes in the returned set
     * are reflected in this set, and vice-versa.  The returned set supports
     * all optional set operations that this set supports.
     *
     * <p>The returned set will throw an {@code IllegalArgumentException}
     * on an attempt to insert an element outside its range.
     *
     * @param fromElement low endpoint of the returned set
     * @param inclusive {@code true} if the low endpoint
     *        is to be included in the returned view
     * @return a view of the portion of this set whose elements are greater
     *         than or equal to {@code fromElement}
     * @throws ClassCastException if {@code fromElement} is not compatible
     *         with this set's comparator (or, if the set has no comparator,
     *         if {@code fromElement} does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if {@code fromElement} cannot be compared to elements
     *         currently in the set.
     * @throws NullPointerException if {@code fromElement} is null
     *         and this set does not permit null elements
     * @throws IllegalArgumentException if this set itself has a
     *         restricted range, and {@code fromElement} lies outside the
     *         bounds of the range
     */
    NavigableSet<E> tailSet(E fromElement, boolean inclusive);

    /**
     * {@inheritDoc}
     *
     * <p>Equivalent to {@code subSet(fromElement, true, toElement, false)}.
     *
     * @throws ClassCastException       {@inheritDoc}
     * @throws NullPointerException     {@inheritDoc}
     * @throws IllegalArgumentException {@inheritDoc}
     */
    SortedSet<E> subSet(E fromElement, E toElement);

    /**
     * {@inheritDoc}
     *
     * <p>Equivalent to {@code headSet(toElement, false)}.
     *
     * @throws ClassCastException       {@inheritDoc}
     * @throws NullPointerException     {@inheritDoc}
     * @throws IllegalArgumentException {@inheritDoc}
na     */
    SortedSet<E> headSet(E toElement);

    /**
     * {@inheritDoc}
     *
     * <p>Equivalent to {@code tailSet(fromElement, true)}.
     *
     * @throws ClassCastException       {@inheritDoc}
     * @throws NullPointerException     {@inheritDoc}
     * @throws IllegalArgumentException {@inheritDoc}
     */
    SortedSet<E> tailSet(E fromElement);
}
Revision:	1.1
Committed:	Sun Dec 16 20:55:09 2012 UTC (11 years, 5 months ago) by dl
Branch:	MAIN
Log Message:	Create src/jdk7 package
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea and Josh Bloch with assistance from members of JCP
3			* JSR-166 Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7			package java.util;
8
9			/**
10			* A {@link SortedSet} extended with navigation methods reporting
11			* closest matches for given search targets. Methods {@code lower},
12			* {@code floor}, {@code ceiling}, and {@code higher} return elements
13			* respectively less than, less than or equal, greater than or equal,
14			* and greater than a given element, returning {@code null} if there
15			* is no such element. A {@code NavigableSet} may be accessed and
16			* traversed in either ascending or descending order. The {@code
17			* descendingSet} method returns a view of the set with the senses of
18			* all relational and directional methods inverted. The performance of
19			* ascending operations and views is likely to be faster than that of
20			* descending ones. This interface additionally defines methods
21			* {@code pollFirst} and {@code pollLast} that return and remove the
22			* lowest and highest element, if one exists, else returning {@code
23			* null}. Methods {@code subSet}, {@code headSet},
24			* and {@code tailSet} differ from the like-named {@code
25			* SortedSet} methods in accepting additional arguments describing
26			* whether lower and upper bounds are inclusive versus exclusive.
27			* Subsets of any {@code NavigableSet} must implement the {@code
28			* NavigableSet} interface.
29			*
30			* <p>The return values of navigation methods may be ambiguous in
31			* implementations that permit {@code null} elements. However, even
32			* in this case the result can be disambiguated by checking
33			* {@code contains(null)}. To avoid such issues, implementations of
34			* this interface are encouraged to <em>not</em> permit insertion of
35			* {@code null} elements. (Note that sorted sets of {@link
36			* Comparable} elements intrinsically do not permit {@code null}.)
37			*
38			* <p>Methods
39			* {@link #subSet(Object, Object) subSet(E, E)},
40			* {@link #headSet(Object) headSet(E)}, and
41			* {@link #tailSet(Object) tailSet(E)}
42			* are specified to return {@code SortedSet} to allow existing
43			* implementations of {@code SortedSet} to be compatibly retrofitted to
44			* implement {@code NavigableSet}, but extensions and implementations
45			* of this interface are encouraged to override these methods to return
46			* {@code NavigableSet}.
47			*
48			* <p>This interface is a member of the
49			* <a href="{@docRoot}/../technotes/guides/collections/index.html">
50			* Java Collections Framework</a>.
51			*
52			* @author Doug Lea
53			* @author Josh Bloch
54			* @param <E> the type of elements maintained by this set
55			* @since 1.6
56			*/
57			public interface NavigableSet<E> extends SortedSet<E> {
58			/**
59			* Returns the greatest element in this set strictly less than the
60			* given element, or {@code null} if there is no such element.
61			*
62			* @param e the value to match
63			* @return the greatest element less than {@code e},
64			* or {@code null} if there is no such element
65			* @throws ClassCastException if the specified element cannot be
66			* compared with the elements currently in the set
67			* @throws NullPointerException if the specified element is null
68			* and this set does not permit null elements
69			*/
70			E lower(E e);
71
72			/**
73			* Returns the greatest element in this set less than or equal to
74			* the given element, or {@code null} if there is no such element.
75			*
76			* @param e the value to match
77			* @return the greatest element less than or equal to {@code e},
78			* or {@code null} if there is no such element
79			* @throws ClassCastException if the specified element cannot be
80			* compared with the elements currently in the set
81			* @throws NullPointerException if the specified element is null
82			* and this set does not permit null elements
83			*/
84			E floor(E e);
85
86			/**
87			* Returns the least element in this set greater than or equal to
88			* the given element, or {@code null} if there is no such element.
89			*
90			* @param e the value to match
91			* @return the least element greater than or equal to {@code e},
92			* or {@code null} if there is no such element
93			* @throws ClassCastException if the specified element cannot be
94			* compared with the elements currently in the set
95			* @throws NullPointerException if the specified element is null
96			* and this set does not permit null elements
97			*/
98			E ceiling(E e);
99
100			/**
101			* Returns the least element in this set strictly greater than the
102			* given element, or {@code null} if there is no such element.
103			*
104			* @param e the value to match
105			* @return the least element greater than {@code e},
106			* or {@code null} if there is no such element
107			* @throws ClassCastException if the specified element cannot be
108			* compared with the elements currently in the set
109			* @throws NullPointerException if the specified element is null
110			* and this set does not permit null elements
111			*/
112			E higher(E e);
113
114			/**
115			* Retrieves and removes the first (lowest) element,
116			* or returns {@code null} if this set is empty.
117			*
118			* @return the first element, or {@code null} if this set is empty
119			*/
120			E pollFirst();
121
122			/**
123			* Retrieves and removes the last (highest) element,
124			* or returns {@code null} if this set is empty.
125			*
126			* @return the last element, or {@code null} if this set is empty
127			*/
128			E pollLast();
129
130			/**
131			* Returns an iterator over the elements in this set, in ascending order.
132			*
133			* @return an iterator over the elements in this set, in ascending order
134			*/
135			Iterator<E> iterator();
136
137			/**
138			* Returns a reverse order view of the elements contained in this set.
139			* The descending set is backed by this set, so changes to the set are
140			* reflected in the descending set, and vice-versa. If either set is
141			* modified while an iteration over either set is in progress (except
142			* through the iterator's own {@code remove} operation), the results of
143			* the iteration are undefined.
144			*
145			* <p>The returned set has an ordering equivalent to
146			* <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
147			* The expression {@code s.descendingSet().descendingSet()} returns a
148			* view of {@code s} essentially equivalent to {@code s}.
149			*
150			* @return a reverse order view of this set
151			*/
152			NavigableSet<E> descendingSet();
153
154			/**
155			* Returns an iterator over the elements in this set, in descending order.
156			* Equivalent in effect to {@code descendingSet().iterator()}.
157			*
158			* @return an iterator over the elements in this set, in descending order
159			*/
160			Iterator<E> descendingIterator();
161
162			/**
163			* Returns a view of the portion of this set whose elements range from
164			* {@code fromElement} to {@code toElement}. If {@code fromElement} and
165			* {@code toElement} are equal, the returned set is empty unless {@code
166			* fromExclusive} and {@code toExclusive} are both true. The returned set
167			* is backed by this set, so changes in the returned set are reflected in
168			* this set, and vice-versa. The returned set supports all optional set
169			* operations that this set supports.
170			*
171			* <p>The returned set will throw an {@code IllegalArgumentException}
172			* on an attempt to insert an element outside its range.
173			*
174			* @param fromElement low endpoint of the returned set
175			* @param fromInclusive {@code true} if the low endpoint
176			* is to be included in the returned view
177			* @param toElement high endpoint of the returned set
178			* @param toInclusive {@code true} if the high endpoint
179			* is to be included in the returned view
180			* @return a view of the portion of this set whose elements range from
181			* {@code fromElement}, inclusive, to {@code toElement}, exclusive
182			* @throws ClassCastException if {@code fromElement} and
183			* {@code toElement} cannot be compared to one another using this
184			* set's comparator (or, if the set has no comparator, using
185			* natural ordering). Implementations may, but are not required
186			* to, throw this exception if {@code fromElement} or
187			* {@code toElement} cannot be compared to elements currently in
188			* the set.
189			* @throws NullPointerException if {@code fromElement} or
190			* {@code toElement} is null and this set does
191			* not permit null elements
192			* @throws IllegalArgumentException if {@code fromElement} is
193			* greater than {@code toElement}; or if this set itself
194			* has a restricted range, and {@code fromElement} or
195			* {@code toElement} lies outside the bounds of the range.
196			*/
197			NavigableSet<E> subSet(E fromElement, boolean fromInclusive,
198			E toElement, boolean toInclusive);
199
200			/**
201			* Returns a view of the portion of this set whose elements are less than
202			* (or equal to, if {@code inclusive} is true) {@code toElement}. The
203			* returned set is backed by this set, so changes in the returned set are
204			* reflected in this set, and vice-versa. The returned set supports all
205			* optional set operations that this set supports.
206			*
207			* <p>The returned set will throw an {@code IllegalArgumentException}
208			* on an attempt to insert an element outside its range.
209			*
210			* @param toElement high endpoint of the returned set
211			* @param inclusive {@code true} if the high endpoint
212			* is to be included in the returned view
213			* @return a view of the portion of this set whose elements are less than
214			* (or equal to, if {@code inclusive} is true) {@code toElement}
215			* @throws ClassCastException if {@code toElement} is not compatible
216			* with this set's comparator (or, if the set has no comparator,
217			* if {@code toElement} does not implement {@link Comparable}).
218			* Implementations may, but are not required to, throw this
219			* exception if {@code toElement} cannot be compared to elements
220			* currently in the set.
221			* @throws NullPointerException if {@code toElement} is null and
222			* this set does not permit null elements
223			* @throws IllegalArgumentException if this set itself has a
224			* restricted range, and {@code toElement} lies outside the
225			* bounds of the range
226			*/
227			NavigableSet<E> headSet(E toElement, boolean inclusive);
228
229			/**
230			* Returns a view of the portion of this set whose elements are greater
231			* than (or equal to, if {@code inclusive} is true) {@code fromElement}.
232			* The returned set is backed by this set, so changes in the returned set
233			* are reflected in this set, and vice-versa. The returned set supports
234			* all optional set operations that this set supports.
235			*
236			* <p>The returned set will throw an {@code IllegalArgumentException}
237			* on an attempt to insert an element outside its range.
238			*
239			* @param fromElement low endpoint of the returned set
240			* @param inclusive {@code true} if the low endpoint
241			* is to be included in the returned view
242			* @return a view of the portion of this set whose elements are greater
243			* than or equal to {@code fromElement}
244			* @throws ClassCastException if {@code fromElement} is not compatible
245			* with this set's comparator (or, if the set has no comparator,
246			* if {@code fromElement} does not implement {@link Comparable}).
247			* Implementations may, but are not required to, throw this
248			* exception if {@code fromElement} cannot be compared to elements
249			* currently in the set.
250			* @throws NullPointerException if {@code fromElement} is null
251			* and this set does not permit null elements
252			* @throws IllegalArgumentException if this set itself has a
253			* restricted range, and {@code fromElement} lies outside the
254			* bounds of the range
255			*/
256			NavigableSet<E> tailSet(E fromElement, boolean inclusive);
257
258			/**
259			* {@inheritDoc}
260			*
261			* <p>Equivalent to {@code subSet(fromElement, true, toElement, false)}.
262			*
263			* @throws ClassCastException {@inheritDoc}
264			* @throws NullPointerException {@inheritDoc}
265			* @throws IllegalArgumentException {@inheritDoc}
266			*/
267			SortedSet<E> subSet(E fromElement, E toElement);
268
269			/**
270			* {@inheritDoc}
271			*
272			* <p>Equivalent to {@code headSet(toElement, false)}.
273			*
274			* @throws ClassCastException {@inheritDoc}
275			* @throws NullPointerException {@inheritDoc}
276			* @throws IllegalArgumentException {@inheritDoc}
277			na */
278			SortedSet<E> headSet(E toElement);
279
280			/**
281			* {@inheritDoc}
282			*
283			* <p>Equivalent to {@code tailSet(fromElement, true)}.
284			*
285			* @throws ClassCastException {@inheritDoc}
286			* @throws NullPointerException {@inheritDoc}
287			* @throws IllegalArgumentException {@inheritDoc}
288			*/
289			SortedSet<E> tailSet(E fromElement);
290			}