src/jsr166x/NavigableSet.java

/*
 * Written by Doug Lea 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 jsr166x;

import 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 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.  A {@code NavigableSet} may be viewed and traversed
 * in either ascending or descending order.  The {@code Collection}
 * {@code iterator} method returns an ascending {@code Iterator} and
 * the additional method {@code descendingIterator} returns
 * descending iterator. The performance of ascending traversals is
 * likely to be faster than descending traversals.  This interface
 * additionally defines methods {@code pollFirst} and
 * {@code pollLast} that return and remove the lowest and highest key,
 * if one exists, else returning {@code null}.
 *
 * <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 <em>not</em> to permit insertion of
 * {@code null} elements. (Note that sorted sets of {@link
 * Comparable} elements intrinsically do not permit {@code null}.)
 *
 * @author Doug Lea
 * @param <E> the type of elements maintained by this set
 */
public interface NavigableSet<E> extends SortedSet<E> {
    /**
     * Returns an element greater than or equal to the given element, or
     * {@code null} if there is no such element.
     *
     * @param o the value to match
     * @return an element greater than or equal to given element, or
     * {@code null} if there is no such element
     * @throws ClassCastException if o cannot be compared with the elements
     *            currently in the set
     * @throws NullPointerException if o is {@code null}
     * and this set deas not permit {@code null} elements
     */
    public E ceiling(E o);

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

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

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

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

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

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

    /**
     * Returns a view of the portion of this set whose elements range from
     * {@code fromElement}, inclusive, to {@code toElement}, exclusive.  (If
     * {@code fromElement} and {@code toElement} are equal, the returned
     * sorted set is empty.)  The returned sorted set is backed by this set,
     * so changes in the returned sorted set are reflected in this set, and
     * vice-versa.
     * @param fromElement low endpoint (inclusive) of the subSet
     * @param toElement high endpoint (exclusive) of the subSet
     * @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)
     * @throws IllegalArgumentException if {@code fromElement} is
     * greater than {@code toElement}
     * @throws NullPointerException if {@code fromElement} or
     *         {@code toElement} is {@code null}
     * and this set deas not permit {@code null} elements
     */
    public NavigableSet<E> subSet(E fromElement, E toElement);

    /**
     * Returns a view of the portion of this set whose elements are strictly
     * less than {@code toElement}.  The returned sorted set is backed by
     * this set, so changes in the returned sorted set are reflected in this
     * set, and vice-versa.
     * @param toElement high endpoint (exclusive) of the headSet
     * @return a view of the portion of this set whose elements are strictly
     *         less than 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 {@code Comparable})
     * @throws NullPointerException if {@code toElement} is {@code null}
     * and this set deas not permit {@code null} elements
     */
    public NavigableSet<E> headSet(E toElement);

    /**
     * Returns a view of the portion of this set whose elements are
     * greater than or equal to {@code fromElement}.  The returned
     * sorted set is backed by this set, so changes in the returned
     * sorted set are reflected in this set, and vice-versa.
     * @param fromElement low endpoint (inclusive) of the tailSet
     * @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
     * {@code Comparable})
     * @throws NullPointerException if {@code fromElement} is {@code null}
     * and this set deas not permit {@code null} elements
     */
    public NavigableSet<E> tailSet(E fromElement);
}
Revision:	1.12
Committed:	Sun Jan 18 20:17:33 2015 UTC (9 years, 3 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.11:	+1 -0 lines
Log Message:	exactly one blank line before and after package statements
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4	jsr166	1.6	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6
7			package jsr166x;
8	jsr166	1.12
9	dl	1.1	import java.util.*;
10
11			/**
12	dl	1.2	* A {@link SortedSet} extended with navigation methods reporting
13	jsr166	1.9	* closest matches for given search targets. Methods {@code lower},
14			* {@code floor}, {@code ceiling}, and {@code higher} return keys
15	dl	1.2	* respectively less than, less than or equal, greater than or equal,
16	jsr166	1.9	* and greater than a given key, returning {@code null} if there is
17			* no such key. A {@code NavigableSet} may be viewed and traversed
18			* in either ascending or descending order. The {@code Collection}
19			* {@code iterator} method returns an ascending {@code Iterator} and
20			* the additional method {@code descendingIterator} returns
21	dl	1.3	* descending iterator. The performance of ascending traversals is
22			* likely to be faster than descending traversals. This interface
23	jsr166	1.9	* additionally defines methods {@code pollFirst} and
24	jsr166	1.10	* {@code pollLast} that return and remove the lowest and highest key,
25	jsr166	1.9	* if one exists, else returning {@code null}.
26	dl	1.1	*
27	jsr166	1.7	* <p>The return values of navigation methods may be ambiguous in
28	jsr166	1.9	* implementations that permit {@code null} elements. However, even
29	dl	1.2	* in this case the result can be disambiguated by checking
30	jsr166	1.9	* {@code contains(null)}. To avoid such issues, implementations of
31	dl	1.2	* this interface are encouraged <em>not</em> to permit insertion of
32	jsr166	1.9	* {@code null} elements. (Note that sorted sets of {@link
33			* Comparable} elements intrinsically do not permit {@code null}.)
34	dl	1.1	*
35			* @author Doug Lea
36			* @param <E> the type of elements maintained by this set
37			*/
38			public interface NavigableSet<E> extends SortedSet<E> {
39			/**
40			* Returns an element greater than or equal to the given element, or
41	jsr166	1.9	* {@code null} if there is no such element.
42	jsr166	1.4	*
43	dl	1.1	* @param o the value to match
44	dl	1.2	* @return an element greater than or equal to given element, or
45	jsr166	1.11	* {@code null} if there is no such element
46	dl	1.1	* @throws ClassCastException if o cannot be compared with the elements
47	jsr166	1.11	* currently in the set
48	jsr166	1.9	* @throws NullPointerException if o is {@code null}
49			* and this set deas not permit {@code null} elements
50	dl	1.1	*/
51			public E ceiling(E o);
52
53			/**
54	dl	1.2	* Returns an element strictly less than the given element, or
55	jsr166	1.9	* {@code null} if there is no such element.
56	jsr166	1.4	*
57	dl	1.1	* @param o the value to match
58			* @return the greatest element less than the given element, or
59	jsr166	1.11	* {@code null} if there is no such element
60	dl	1.1	* @throws ClassCastException if o cannot be compared with the elements
61	jsr166	1.8	* currently in the set
62	jsr166	1.9	* @throws NullPointerException if o is {@code null}
63			* and this set deas not permit {@code null} elements
64	dl	1.1	*/
65			public E lower(E o);
66
67			/**
68	dl	1.2	* Returns an element less than or equal to the given element, or
69	jsr166	1.9	* {@code null} if there is no such element.
70	jsr166	1.4	*
71	dl	1.1	* @param o the value to match
72			* @return the greatest element less than or equal to given
73	jsr166	1.9	* element, or {@code null} if there is no such element
74	dl	1.1	* @throws ClassCastException if o cannot be compared with the elements
75	jsr166	1.8	* currently in the set
76	jsr166	1.9	* @throws NullPointerException if o is {@code null}
77			* and this set deas not permit {@code null} elements
78	dl	1.1	*/
79			public E floor(E o);
80
81			/**
82	dl	1.2	* Returns an element strictly greater than the given element, or
83	jsr166	1.9	* {@code null} if there is no such element.
84	jsr166	1.4	*
85	dl	1.1	* @param o the value to match
86			* @return the least element greater than the given element, or
87	jsr166	1.11	* {@code null} if there is no such element
88	dl	1.1	* @throws ClassCastException if o cannot be compared with the elements
89	jsr166	1.8	* currently in the set
90	jsr166	1.9	* @throws NullPointerException if o is {@code null}
91			* and this set deas not permit {@code null} elements
92	dl	1.1	*/
93			public E higher(E o);
94
95			/**
96			* Retrieves and removes the first (lowest) element.
97			*
98	jsr166	1.9	* @return the first element, or {@code null} if empty
99	dl	1.1	*/
100			public E pollFirst();
101
102			/**
103			* Retrieves and removes the last (highest) element.
104			*
105	jsr166	1.9	* @return the last element, or {@code null} if empty
106	dl	1.1	*/
107			public E pollLast();
108
109			/**
110	dl	1.3	* Returns an iterator over the elements in this collection, in
111	jsr166	1.4	* descending order.
112			*
113	jsr166	1.9	* @return an {@code Iterator} over the elements in this collection
114	dl	1.3	*/
115			Iterator<E> descendingIterator();
116
117			/**
118	dl	1.1	* Returns a view of the portion of this set whose elements range from
119	jsr166	1.9	* {@code fromElement}, inclusive, to {@code toElement}, exclusive. (If
120			* {@code fromElement} and {@code toElement} are equal, the returned
121	dl	1.1	* sorted set is empty.) The returned sorted set is backed by this set,
122			* so changes in the returned sorted set are reflected in this set, and
123	jsr166	1.4	* vice-versa.
124	jsr166	1.8	* @param fromElement low endpoint (inclusive) of the subSet
125			* @param toElement high endpoint (exclusive) of the subSet
126	dl	1.1	* @return a view of the portion of this set whose elements range from
127	jsr166	1.9	* {@code fromElement}, inclusive, to {@code toElement},
128	jsr166	1.8	* exclusive
129	jsr166	1.9	* @throws ClassCastException if {@code fromElement} and
130			* {@code toElement} cannot be compared to one another using
131	dl	1.1	* this set's comparator (or, if the set has no comparator,
132	jsr166	1.8	* using natural ordering)
133	jsr166	1.9	* @throws IllegalArgumentException if {@code fromElement} is
134			* greater than {@code toElement}
135			* @throws NullPointerException if {@code fromElement} or
136			* {@code toElement} is {@code null}
137			* and this set deas not permit {@code null} elements
138	dl	1.1	*/
139			public NavigableSet<E> subSet(E fromElement, E toElement);
140
141			/**
142			* Returns a view of the portion of this set whose elements are strictly
143	jsr166	1.9	* less than {@code toElement}. The returned sorted set is backed by
144	dl	1.1	* this set, so changes in the returned sorted set are reflected in this
145	jsr166	1.4	* set, and vice-versa.
146	jsr166	1.8	* @param toElement high endpoint (exclusive) of the headSet
147	dl	1.1	* @return a view of the portion of this set whose elements are strictly
148	jsr166	1.8	* less than toElement
149	jsr166	1.9	* @throws ClassCastException if {@code toElement} is not compatible
150	dl	1.1	* with this set's comparator (or, if the set has no comparator,
151	jsr166	1.9	* if {@code toElement} does not implement {@code Comparable})
152			* @throws NullPointerException if {@code toElement} is {@code null}
153			* and this set deas not permit {@code null} elements
154	dl	1.1	*/
155			public NavigableSet<E> headSet(E toElement);
156
157			/**
158			* Returns a view of the portion of this set whose elements are
159	jsr166	1.9	* greater than or equal to {@code fromElement}. The returned
160	dl	1.1	* sorted set is backed by this set, so changes in the returned
161			* sorted set are reflected in this set, and vice-versa.
162	jsr166	1.8	* @param fromElement low endpoint (inclusive) of the tailSet
163	dl	1.1	* @return a view of the portion of this set whose elements are
164	jsr166	1.9	* greater than or equal to {@code fromElement}
165			* @throws ClassCastException if {@code fromElement} is not
166	dl	1.1	* compatible with this set's comparator (or, if the set has no
167	jsr166	1.9	* comparator, if {@code fromElement} does not implement
168			* {@code Comparable})
169			* @throws NullPointerException if {@code fromElement} is {@code null}
170			* and this set deas not permit {@code null} elements
171	dl	1.1	*/
172			public NavigableSet<E> tailSet(E fromElement);
173			}