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root/jsr166/jsr166/src/main/java/util/NavigableSet.java
Revision: 1.26
Committed: Sun Nov 18 18:03:10 2012 UTC (11 years, 6 months ago) by jsr166
Branch: MAIN
Changes since 1.25: +1 -1 lines
Log Message: 
normalize whitespace after <p>

File Contents

# User Rev Content
1 dl 1.1 /*
2 dl 1.15 * 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 jsr166 1.25 * http://creativecommons.org/publicdomain/zero/1.0/
5 dl 1.1 */
6    
7     package java.util;
8    
9     /**
10     * A {@link SortedSet} extended with navigation methods reporting
11 jsr166 1.18 * closest matches for given search targets. Methods {@code lower},
12 dl 1.15 * {@code floor}, {@code ceiling}, and {@code higher} return elements
13 dl 1.1 * respectively less than, less than or equal, greater than or equal,
14 dl 1.15 * 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 dl 1.16 * null}. Methods {@code subSet}, {@code headSet},
24     * and {@code tailSet} differ from the like-named {@code
25 dl 1.15 * 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 dl 1.1 *
30 jsr166 1.26 * <p>The return values of navigation methods may be ambiguous in
31 dl 1.15 * implementations that permit {@code null} elements. However, even
32 dl 1.1 * in this case the result can be disambiguated by checking
33 dl 1.15 * {@code contains(null)}. To avoid such issues, implementations of
34 jsr166 1.9 * this interface are encouraged to <em>not</em> permit insertion of
35 dl 1.15 * {@code null} elements. (Note that sorted sets of {@link
36     * Comparable} elements intrinsically do not permit {@code null}.)
37 dl 1.1 *
38 jsr166 1.23 * <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 jsr166 1.24 *
48 jsr166 1.8 * <p>This interface is a member of the
49 jsr166 1.23 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
50 jsr166 1.8 * Java Collections Framework</a>.
51     *
52 dl 1.1 * @author Doug Lea
53 dl 1.15 * @author Josh Bloch
54 dl 1.1 * @param <E> the type of elements maintained by this set
55 jsr166 1.7 * @since 1.6
56 dl 1.1 */
57     public interface NavigableSet<E> extends SortedSet<E> {
58     /**
59 jsr166 1.9 * Returns the greatest element in this set strictly less than the
60 dl 1.15 * given element, or {@code null} if there is no such element.
61 jsr166 1.6 *
62 jsr166 1.5 * @param e the value to match
63 dl 1.15 * @return the greatest element less than {@code e},
64     * or {@code null} if there is no such element
65 jsr166 1.9 * @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 dl 1.1 */
70 jsr166 1.9 E lower(E e);
71 dl 1.1
72     /**
73 jsr166 1.9 * Returns the greatest element in this set less than or equal to
74 dl 1.15 * the given element, or {@code null} if there is no such element.
75 jsr166 1.6 *
76 jsr166 1.5 * @param e the value to match
77 dl 1.15 * @return the greatest element less than or equal to {@code e},
78     * or {@code null} if there is no such element
79 jsr166 1.9 * @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 dl 1.1 */
84 jsr166 1.9 E floor(E e);
85 dl 1.1
86     /**
87 jsr166 1.9 * Returns the least element in this set greater than or equal to
88 dl 1.15 * the given element, or {@code null} if there is no such element.
89 jsr166 1.6 *
90 jsr166 1.5 * @param e the value to match
91 dl 1.15 * @return the least element greater than or equal to {@code e},
92     * or {@code null} if there is no such element
93 jsr166 1.9 * @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 dl 1.1 */
98 jsr166 1.9 E ceiling(E e);
99 dl 1.1
100     /**
101 jsr166 1.9 * Returns the least element in this set strictly greater than the
102 dl 1.15 * given element, or {@code null} if there is no such element.
103 jsr166 1.6 *
104 jsr166 1.5 * @param e the value to match
105 dl 1.15 * @return the least element greater than {@code e},
106     * or {@code null} if there is no such element
107 jsr166 1.9 * @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 dl 1.1 */
112 jsr166 1.5 E higher(E e);
113 dl 1.1
114     /**
115 jsr166 1.13 * Retrieves and removes the first (lowest) element,
116 dl 1.15 * or returns {@code null} if this set is empty.
117 dl 1.1 *
118 dl 1.15 * @return the first element, or {@code null} if this set is empty
119 dl 1.1 */
120 dl 1.3 E pollFirst();
121 dl 1.1
122     /**
123 jsr166 1.13 * Retrieves and removes the last (highest) element,
124 dl 1.15 * or returns {@code null} if this set is empty.
125 dl 1.1 *
126 dl 1.15 * @return the last element, or {@code null} if this set is empty
127 dl 1.1 */
128 dl 1.3 E pollLast();
129 dl 1.1
130     /**
131 jsr166 1.10 * Returns an iterator over the elements in this set, in ascending order.
132 jsr166 1.6 *
133 jsr166 1.10 * @return an iterator over the elements in this set, in ascending order
134     */
135     Iterator<E> iterator();
136    
137     /**
138 jsr166 1.23 * 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 dl 1.15 *
150 jsr166 1.23 * @return a reverse order view of this set
151 dl 1.15 */
152     NavigableSet<E> descendingSet();
153    
154     /**
155 jsr166 1.10 * Returns an iterator over the elements in this set, in descending order.
156 jsr166 1.22 * Equivalent in effect to {@code descendingSet().iterator()}.
157 jsr166 1.10 *
158     * @return an iterator over the elements in this set, in descending order
159 dl 1.1 */
160     Iterator<E> descendingIterator();
161    
162     /**
163 dl 1.15 * 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 dl 1.3 *
171 dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
172 jsr166 1.9 * on an attempt to insert an element outside its range.
173     *
174 dl 1.15 * @param fromElement low endpoint of the returned set
175 jsr166 1.21 * @param fromInclusive {@code true} if the low endpoint
176     * is to be included in the returned view
177 dl 1.15 * @param toElement high endpoint of the returned set
178 jsr166 1.21 * @param toInclusive {@code true} if the high endpoint
179     * is to be included in the returned view
180 dl 1.1 * @return a view of the portion of this set whose elements range from
181 dl 1.15 * {@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 jsr166 1.9 * set's comparator (or, if the set has no comparator, using
185     * natural ordering). Implementations may, but are not required
186 dl 1.15 * to, throw this exception if {@code fromElement} or
187     * {@code toElement} cannot be compared to elements currently in
188 jsr166 1.9 * the set.
189 dl 1.15 * @throws NullPointerException if {@code fromElement} or
190     * {@code toElement} is null and this set does
191 jsr166 1.9 * not permit null elements
192 dl 1.15 * @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 dl 1.16 NavigableSet<E> subSet(E fromElement, boolean fromInclusive,
198     E toElement, boolean toInclusive);
199 dl 1.1
200     /**
201 dl 1.15 * 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 jsr166 1.9 *
207 dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
208 jsr166 1.9 * on an attempt to insert an element outside its range.
209     *
210 dl 1.15 * @param toElement high endpoint of the returned set
211 jsr166 1.21 * @param inclusive {@code true} if the high endpoint
212     * is to be included in the returned view
213 dl 1.15 * @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 dl 1.1 * with this set's comparator (or, if the set has no comparator,
217 dl 1.15 * if {@code toElement} does not implement {@link Comparable}).
218 jsr166 1.9 * Implementations may, but are not required to, throw this
219 dl 1.15 * exception if {@code toElement} cannot be compared to elements
220 jsr166 1.9 * currently in the set.
221 dl 1.15 * @throws NullPointerException if {@code toElement} is null and
222 jsr166 1.9 * this set does not permit null elements
223     * @throws IllegalArgumentException if this set itself has a
224 dl 1.15 * restricted range, and {@code toElement} lies outside the
225 jsr166 1.9 * bounds of the range
226 dl 1.1 */
227 dl 1.16 NavigableSet<E> headSet(E toElement, boolean inclusive);
228 dl 1.1
229     /**
230 dl 1.15 * 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 jsr166 1.9 *
236 dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
237 jsr166 1.9 * on an attempt to insert an element outside its range.
238     *
239 dl 1.15 * @param fromElement low endpoint of the returned set
240 jsr166 1.21 * @param inclusive {@code true} if the low endpoint
241     * is to be included in the returned view
242 jsr166 1.9 * @return a view of the portion of this set whose elements are greater
243 dl 1.15 * than or equal to {@code fromElement}
244     * @throws ClassCastException if {@code fromElement} is not compatible
245 jsr166 1.9 * with this set's comparator (or, if the set has no comparator,
246 dl 1.15 * if {@code fromElement} does not implement {@link Comparable}).
247 jsr166 1.9 * Implementations may, but are not required to, throw this
248 dl 1.15 * exception if {@code fromElement} cannot be compared to elements
249 jsr166 1.9 * currently in the set.
250 dl 1.15 * @throws NullPointerException if {@code fromElement} is null
251 jsr166 1.9 * and this set does not permit null elements
252     * @throws IllegalArgumentException if this set itself has a
253 dl 1.15 * restricted range, and {@code fromElement} lies outside the
254 jsr166 1.9 * bounds of the range
255 dl 1.1 */
256 dl 1.16 NavigableSet<E> tailSet(E fromElement, boolean inclusive);
257 jsr166 1.21
258     /**
259 jsr166 1.23 * {@inheritDoc}
260 jsr166 1.21 *
261 jsr166 1.23 * <p>Equivalent to {@code subSet(fromElement, true, toElement, false)}.
262 jsr166 1.21 *
263     * @throws ClassCastException {@inheritDoc}
264     * @throws NullPointerException {@inheritDoc}
265     * @throws IllegalArgumentException {@inheritDoc}
266     */
267     SortedSet<E> subSet(E fromElement, E toElement);
268    
269     /**
270 jsr166 1.23 * {@inheritDoc}
271 jsr166 1.21 *
272 jsr166 1.23 * <p>Equivalent to {@code headSet(toElement, false)}.
273 jsr166 1.21 *
274     * @throws ClassCastException {@inheritDoc}
275     * @throws NullPointerException {@inheritDoc}
276     * @throws IllegalArgumentException {@inheritDoc}
277 jsr166 1.23 na */
278 jsr166 1.21 SortedSet<E> headSet(E toElement);
279    
280     /**
281 jsr166 1.23 * {@inheritDoc}
282 jsr166 1.21 *
283 jsr166 1.23 * <p>Equivalent to {@code tailSet(fromElement, true)}.
284 jsr166 1.21 *
285     * @throws ClassCastException {@inheritDoc}
286     * @throws NullPointerException {@inheritDoc}
287     * @throws IllegalArgumentException {@inheritDoc}
288     */
289     SortedSet<E> tailSet(E fromElement);
290 dl 1.1 }