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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 1.27 * closest matches for given search targets. Methods {@link #lower},
12 :     * {@link #floor}, {@link #ceiling}, and {@link #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 : jsr166 1.31 * is no such element.
16 :     *
17 :     * <p>A {@code NavigableSet} may be accessed and traversed in either
18 :     * ascending or descending order. The {@link #descendingSet} method
19 :     * returns a view of the set with the senses of all relational and
20 :     * directional methods inverted. The performance of ascending
21 :     * operations and views is likely to be faster than that of descending
22 :     * ones. This interface additionally defines methods {@link
23 :     * #pollFirst} and {@link #pollLast} that return and remove the lowest
24 :     * and highest element, if one exists, else returning {@code null}.
25 :     * Methods
26 :     * {@link #subSet(Object, boolean, Object, boolean) subSet(E, boolean, E, boolean)},
27 :     * {@link #headSet(Object, boolean) headSet(E, boolean)}, and
28 :     * {@link #tailSet(Object, boolean) tailSet(E, boolean)}
29 :     * differ from the like-named {@code SortedSet} methods in accepting
30 :     * additional arguments describing whether lower and upper bounds are
31 :     * inclusive versus exclusive. Subsets of any {@code NavigableSet}
32 :     * must implement the {@code NavigableSet} interface.
33 : dl 1.1 *
34 : jsr166 1.26 * <p>The return values of navigation methods may be ambiguous in
35 : dl 1.15 * implementations that permit {@code null} elements. However, even
36 : dl 1.1 * in this case the result can be disambiguated by checking
37 : dl 1.15 * {@code contains(null)}. To avoid such issues, implementations of
38 : jsr166 1.9 * this interface are encouraged to <em>not</em> permit insertion of
39 : dl 1.15 * {@code null} elements. (Note that sorted sets of {@link
40 :     * Comparable} elements intrinsically do not permit {@code null}.)
41 : dl 1.1 *
42 : jsr166 1.23 * <p>Methods
43 :     * {@link #subSet(Object, Object) subSet(E, E)},
44 :     * {@link #headSet(Object) headSet(E)}, and
45 :     * {@link #tailSet(Object) tailSet(E)}
46 :     * are specified to return {@code SortedSet} to allow existing
47 :     * implementations of {@code SortedSet} to be compatibly retrofitted to
48 :     * implement {@code NavigableSet}, but extensions and implementations
49 :     * of this interface are encouraged to override these methods to return
50 :     * {@code NavigableSet}.
51 : jsr166 1.24 *
52 : jsr166 1.8 * <p>This interface is a member of the
53 : jsr166 1.23 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
54 : jsr166 1.8 * Java Collections Framework</a>.
55 :     *
56 : dl 1.1 * @author Doug Lea
57 : dl 1.15 * @author Josh Bloch
58 : dl 1.1 * @param <E> the type of elements maintained by this set
59 : jsr166 1.7 * @since 1.6
60 : dl 1.1 */
61 :     public interface NavigableSet<E> extends SortedSet<E> {
62 :     /**
63 : jsr166 1.9 * Returns the greatest element in this set strictly less than the
64 : dl 1.15 * given element, or {@code null} if there is no such element.
65 : jsr166 1.6 *
66 : jsr166 1.5 * @param e the value to match
67 : dl 1.15 * @return the greatest element less than {@code e},
68 :     * or {@code null} if there is no such element
69 : jsr166 1.9 * @throws ClassCastException if the specified element cannot be
70 :     * compared with the elements currently in the set
71 :     * @throws NullPointerException if the specified element is null
72 :     * and this set does not permit null elements
73 : dl 1.1 */
74 : jsr166 1.9 E lower(E e);
75 : dl 1.1
76 :     /**
77 : jsr166 1.9 * Returns the greatest element in this set less than or equal to
78 : dl 1.15 * the given element, or {@code null} if there is no such element.
79 : jsr166 1.6 *
80 : jsr166 1.5 * @param e the value to match
81 : dl 1.15 * @return the greatest element less than or equal to {@code e},
82 :     * or {@code null} if there is no such element
83 : jsr166 1.9 * @throws ClassCastException if the specified element cannot be
84 :     * compared with the elements currently in the set
85 :     * @throws NullPointerException if the specified element is null
86 :     * and this set does not permit null elements
87 : dl 1.1 */
88 : jsr166 1.9 E floor(E e);
89 : dl 1.1
90 :     /**
91 : jsr166 1.9 * Returns the least element in this set greater than or equal to
92 : dl 1.15 * the given element, or {@code null} if there is no such element.
93 : jsr166 1.6 *
94 : jsr166 1.5 * @param e the value to match
95 : dl 1.15 * @return the least element greater than or equal to {@code e},
96 :     * or {@code null} if there is no such element
97 : jsr166 1.9 * @throws ClassCastException if the specified element cannot be
98 :     * compared with the elements currently in the set
99 :     * @throws NullPointerException if the specified element is null
100 :     * and this set does not permit null elements
101 : dl 1.1 */
102 : jsr166 1.9 E ceiling(E e);
103 : dl 1.1
104 :     /**
105 : jsr166 1.9 * Returns the least element in this set strictly greater than the
106 : dl 1.15 * given element, or {@code null} if there is no such element.
107 : jsr166 1.6 *
108 : jsr166 1.5 * @param e the value to match
109 : dl 1.15 * @return the least element greater than {@code e},
110 :     * or {@code null} if there is no such element
111 : jsr166 1.9 * @throws ClassCastException if the specified element cannot be
112 :     * compared with the elements currently in the set
113 :     * @throws NullPointerException if the specified element is null
114 :     * and this set does not permit null elements
115 : dl 1.1 */
116 : jsr166 1.5 E higher(E e);
117 : dl 1.1
118 :     /**
119 : jsr166 1.13 * Retrieves and removes the first (lowest) element,
120 : dl 1.15 * or returns {@code null} if this set is empty.
121 : dl 1.1 *
122 : dl 1.15 * @return the first element, or {@code null} if this set is empty
123 : dl 1.1 */
124 : dl 1.3 E pollFirst();
125 : dl 1.1
126 :     /**
127 : jsr166 1.13 * Retrieves and removes the last (highest) element,
128 : dl 1.15 * or returns {@code null} if this set is empty.
129 : dl 1.1 *
130 : dl 1.15 * @return the last element, or {@code null} if this set is empty
131 : dl 1.1 */
132 : dl 1.3 E pollLast();
133 : dl 1.1
134 :     /**
135 : jsr166 1.10 * Returns an iterator over the elements in this set, in ascending order.
136 : jsr166 1.6 *
137 : jsr166 1.10 * @return an iterator over the elements in this set, in ascending order
138 :     */
139 :     Iterator<E> iterator();
140 :    
141 :     /**
142 : jsr166 1.23 * Returns a reverse order view of the elements contained in this set.
143 :     * The descending set is backed by this set, so changes to the set are
144 :     * reflected in the descending set, and vice-versa. If either set is
145 :     * modified while an iteration over either set is in progress (except
146 :     * through the iterator's own {@code remove} operation), the results of
147 :     * the iteration are undefined.
148 :     *
149 :     * <p>The returned set has an ordering equivalent to
150 : jsr166 1.28 * {@link Collections#reverseOrder(Comparator) Collections.reverseOrder}{@code (comparator())}.
151 : jsr166 1.23 * The expression {@code s.descendingSet().descendingSet()} returns a
152 :     * view of {@code s} essentially equivalent to {@code s}.
153 : dl 1.15 *
154 : jsr166 1.23 * @return a reverse order view of this set
155 : dl 1.15 */
156 :     NavigableSet<E> descendingSet();
157 :    
158 :     /**
159 : jsr166 1.10 * Returns an iterator over the elements in this set, in descending order.
160 : jsr166 1.22 * Equivalent in effect to {@code descendingSet().iterator()}.
161 : jsr166 1.10 *
162 :     * @return an iterator over the elements in this set, in descending order
163 : dl 1.1 */
164 :     Iterator<E> descendingIterator();
165 :    
166 :     /**
167 : dl 1.15 * Returns a view of the portion of this set whose elements range from
168 :     * {@code fromElement} to {@code toElement}. If {@code fromElement} and
169 :     * {@code toElement} are equal, the returned set is empty unless {@code
170 : jsr166 1.30 * fromInclusive} and {@code toInclusive} are both true. The returned set
171 : dl 1.15 * is backed by this set, so changes in the returned set are reflected in
172 :     * this set, and vice-versa. The returned set supports all optional set
173 :     * operations that this set supports.
174 : dl 1.3 *
175 : dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
176 : jsr166 1.9 * on an attempt to insert an element outside its range.
177 :     *
178 : dl 1.15 * @param fromElement low endpoint of the returned set
179 : jsr166 1.21 * @param fromInclusive {@code true} if the low endpoint
180 :     * is to be included in the returned view
181 : dl 1.15 * @param toElement high endpoint of the returned set
182 : jsr166 1.21 * @param toInclusive {@code true} if the high endpoint
183 :     * is to be included in the returned view
184 : dl 1.1 * @return a view of the portion of this set whose elements range from
185 : dl 1.15 * {@code fromElement}, inclusive, to {@code toElement}, exclusive
186 :     * @throws ClassCastException if {@code fromElement} and
187 :     * {@code toElement} cannot be compared to one another using this
188 : jsr166 1.9 * set's comparator (or, if the set has no comparator, using
189 :     * natural ordering). Implementations may, but are not required
190 : dl 1.15 * to, throw this exception if {@code fromElement} or
191 :     * {@code toElement} cannot be compared to elements currently in
192 : jsr166 1.9 * the set.
193 : dl 1.15 * @throws NullPointerException if {@code fromElement} or
194 :     * {@code toElement} is null and this set does
195 : jsr166 1.9 * not permit null elements
196 : dl 1.15 * @throws IllegalArgumentException if {@code fromElement} is
197 :     * greater than {@code toElement}; or if this set itself
198 :     * has a restricted range, and {@code fromElement} or
199 :     * {@code toElement} lies outside the bounds of the range.
200 :     */
201 : dl 1.16 NavigableSet<E> subSet(E fromElement, boolean fromInclusive,
202 :     E toElement, boolean toInclusive);
203 : dl 1.1
204 :     /**
205 : dl 1.15 * Returns a view of the portion of this set whose elements are less than
206 :     * (or equal to, if {@code inclusive} is true) {@code toElement}. The
207 :     * returned set is backed by this set, so changes in the returned set are
208 :     * reflected in this set, and vice-versa. The returned set supports all
209 :     * optional set operations that this set supports.
210 : jsr166 1.9 *
211 : dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
212 : jsr166 1.9 * on an attempt to insert an element outside its range.
213 :     *
214 : dl 1.15 * @param toElement high endpoint of the returned set
215 : jsr166 1.21 * @param inclusive {@code true} if the high endpoint
216 :     * is to be included in the returned view
217 : dl 1.15 * @return a view of the portion of this set whose elements are less than
218 :     * (or equal to, if {@code inclusive} is true) {@code toElement}
219 :     * @throws ClassCastException if {@code toElement} is not compatible
220 : dl 1.1 * with this set's comparator (or, if the set has no comparator,
221 : dl 1.15 * if {@code toElement} does not implement {@link Comparable}).
222 : jsr166 1.9 * Implementations may, but are not required to, throw this
223 : dl 1.15 * exception if {@code toElement} cannot be compared to elements
224 : jsr166 1.9 * currently in the set.
225 : dl 1.15 * @throws NullPointerException if {@code toElement} is null and
226 : jsr166 1.9 * this set does not permit null elements
227 :     * @throws IllegalArgumentException if this set itself has a
228 : dl 1.15 * restricted range, and {@code toElement} lies outside the
229 : jsr166 1.9 * bounds of the range
230 : dl 1.1 */
231 : dl 1.16 NavigableSet<E> headSet(E toElement, boolean inclusive);
232 : dl 1.1
233 :     /**
234 : dl 1.15 * Returns a view of the portion of this set whose elements are greater
235 :     * than (or equal to, if {@code inclusive} is true) {@code fromElement}.
236 :     * The returned set is backed by this set, so changes in the returned set
237 :     * are reflected in this set, and vice-versa. The returned set supports
238 :     * all optional set operations that this set supports.
239 : jsr166 1.9 *
240 : dl 1.15 * <p>The returned set will throw an {@code IllegalArgumentException}
241 : jsr166 1.9 * on an attempt to insert an element outside its range.
242 :     *
243 : dl 1.15 * @param fromElement low endpoint of the returned set
244 : jsr166 1.21 * @param inclusive {@code true} if the low endpoint
245 :     * is to be included in the returned view
246 : jsr166 1.9 * @return a view of the portion of this set whose elements are greater
247 : dl 1.15 * than or equal to {@code fromElement}
248 :     * @throws ClassCastException if {@code fromElement} is not compatible
249 : jsr166 1.9 * with this set's comparator (or, if the set has no comparator,
250 : dl 1.15 * if {@code fromElement} does not implement {@link Comparable}).
251 : jsr166 1.9 * Implementations may, but are not required to, throw this
252 : dl 1.15 * exception if {@code fromElement} cannot be compared to elements
253 : jsr166 1.9 * currently in the set.
254 : dl 1.15 * @throws NullPointerException if {@code fromElement} is null
255 : jsr166 1.9 * and this set does not permit null elements
256 :     * @throws IllegalArgumentException if this set itself has a
257 : dl 1.15 * restricted range, and {@code fromElement} lies outside the
258 : jsr166 1.9 * bounds of the range
259 : dl 1.1 */
260 : dl 1.16 NavigableSet<E> tailSet(E fromElement, boolean inclusive);
261 : jsr166 1.21
262 :     /**
263 : jsr166 1.23 * {@inheritDoc}
264 : jsr166 1.21 *
265 : jsr166 1.23 * <p>Equivalent to {@code subSet(fromElement, true, toElement, false)}.
266 : jsr166 1.21 *
267 :     * @throws ClassCastException {@inheritDoc}
268 :     * @throws NullPointerException {@inheritDoc}
269 :     * @throws IllegalArgumentException {@inheritDoc}
270 :     */
271 :     SortedSet<E> subSet(E fromElement, E toElement);
272 :    
273 :     /**
274 : jsr166 1.23 * {@inheritDoc}
275 : jsr166 1.21 *
276 : jsr166 1.23 * <p>Equivalent to {@code headSet(toElement, false)}.
277 : jsr166 1.21 *
278 :     * @throws ClassCastException {@inheritDoc}
279 :     * @throws NullPointerException {@inheritDoc}
280 :     * @throws IllegalArgumentException {@inheritDoc}
281 : jsr166 1.29 */
282 : jsr166 1.21 SortedSet<E> headSet(E toElement);
283 :    
284 :     /**
285 : jsr166 1.23 * {@inheritDoc}
286 : jsr166 1.21 *
287 : jsr166 1.23 * <p>Equivalent to {@code tailSet(fromElement, true)}.
288 : jsr166 1.21 *
289 :     * @throws ClassCastException {@inheritDoc}
290 :     * @throws NullPointerException {@inheritDoc}
291 :     * @throws IllegalArgumentException {@inheritDoc}
292 :     */
293 :     SortedSet<E> tailSet(E fromElement);
294 : dl 1.1 }

Doug Lea
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