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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 :     * http://creativecommons.org/licenses/publicdomain
5 :     */
6 :    
7 :     package java.util;
8 : jsr166 1.12 import java.util.*; // for javadoc (till 6280605 is fixed)
9 : dl 1.1
10 :     /**
11 :     * A {@link SortedSet} extended with navigation methods reporting
12 :     * closest matches for given search targets. Methods <tt>lower</tt>,
13 : jsr166 1.9 * <tt>floor</tt>, <tt>ceiling</tt>, and <tt>higher</tt> return elements
14 : dl 1.1 * respectively less than, less than or equal, greater than or equal,
15 : jsr166 1.9 * and greater than a given element, returning <tt>null</tt> if there is
16 :     * no such element. A <tt>NavigableSet</tt> may be viewed and traversed
17 : dl 1.1 * in either ascending or descending order. The <tt>Collection</tt>
18 :     * <tt>iterator</tt> method returns an ascending <tt>Iterator</tt> and
19 : jsr166 1.9 * the additional method <tt>descendingIterator</tt> returns a
20 : dl 1.1 * descending iterator. The performance of ascending traversals is
21 :     * likely to be faster than descending traversals. This interface
22 :     * additionally defines methods <tt>pollFirst</tt> and
23 : jsr166 1.9 * <tt>pollLast</tt> that return and remove the lowest and highest
24 :     * element, if one exists, else returning <tt>null</tt>.
25 : dl 1.4 * Methods <tt>navigableSubSet</tt>, <tt>navigableHeadSet</tt>, and
26 :     * <tt>navigableTailSet</tt> differ from the similarly named
27 : dl 1.11 * <tt>SortedSet</tt> methods only in their declared return types.
28 : jsr166 1.12 * Subsets of any <tt>NavigableSet</tt> must implement the
29 :     * <tt>NavigableSet</tt> interface.
30 : dl 1.1 *
31 :     * <p> The return values of navigation methods may be ambiguous in
32 :     * implementations that permit <tt>null</tt> elements. However, even
33 :     * in this case the result can be disambiguated by checking
34 :     * <tt>contains(null)</tt>. To avoid such issues, implementations of
35 : jsr166 1.9 * this interface are encouraged to <em>not</em> permit insertion of
36 : dl 1.1 * <tt>null</tt> elements. (Note that sorted sets of {@link
37 :     * Comparable} elements intrinsically do not permit <tt>null</tt>.)
38 :     *
39 : jsr166 1.8 * <p>This interface is a member of the
40 :     * <a href="{@docRoot}/../guide/collections/index.html">
41 :     * Java Collections Framework</a>.
42 :     *
43 : dl 1.1 * @author Doug Lea
44 :     * @param <E> the type of elements maintained by this set
45 : jsr166 1.7 * @since 1.6
46 : dl 1.1 */
47 :     public interface NavigableSet<E> extends SortedSet<E> {
48 :     /**
49 : jsr166 1.9 * Returns the greatest element in this set strictly less than the
50 :     * given element, or <tt>null</tt> if there is no such element.
51 : jsr166 1.6 *
52 : jsr166 1.5 * @param e the value to match
53 : jsr166 1.9 * @return the greatest element less than <tt>e</tt>,
54 :     * or <tt>null</tt> if there is no such element
55 :     * @throws ClassCastException if the specified element cannot be
56 :     * compared with the elements currently in the set
57 :     * @throws NullPointerException if the specified element is null
58 :     * and this set does not permit null elements
59 : dl 1.1 */
60 : jsr166 1.9 E lower(E e);
61 : dl 1.1
62 :     /**
63 : jsr166 1.9 * Returns the greatest element in this set less than or equal to
64 :     * the given element, or <tt>null</tt> if there is no such element.
65 : jsr166 1.6 *
66 : jsr166 1.5 * @param e the value to match
67 : jsr166 1.9 * @return the greatest element less than or equal to <tt>e</tt>,
68 :     * or <tt>null</tt> if there is no such element
69 :     * @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 floor(E e);
75 : dl 1.1
76 :     /**
77 : jsr166 1.9 * Returns the least element in this set greater than or equal to
78 :     * the given element, or <tt>null</tt> if there is no such element.
79 : jsr166 1.6 *
80 : jsr166 1.5 * @param e the value to match
81 : jsr166 1.9 * @return the least element greater than or equal to <tt>e</tt>,
82 :     * or <tt>null</tt> if there is no such element
83 :     * @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 ceiling(E e);
89 : dl 1.1
90 :     /**
91 : jsr166 1.9 * Returns the least element in this set strictly greater than the
92 :     * given element, or <tt>null</tt> if there is no such element.
93 : jsr166 1.6 *
94 : jsr166 1.5 * @param e the value to match
95 : jsr166 1.9 * @return the least element greater than <tt>e</tt>,
96 :     * or <tt>null</tt> if there is no such element
97 :     * @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 1.5 E higher(E e);
103 : dl 1.1
104 :     /**
105 : jsr166 1.13 * Retrieves and removes the first (lowest) element,
106 :     * or returns <tt>null</tt> if this set is empty.
107 : dl 1.1 *
108 : jsr166 1.9 * @return the first element, or <tt>null</tt> if this set is empty
109 : dl 1.1 */
110 : dl 1.3 E pollFirst();
111 : dl 1.1
112 :     /**
113 : jsr166 1.13 * Retrieves and removes the last (highest) element,
114 :     * or returns <tt>null</tt> if this set is empty.
115 : dl 1.1 *
116 : jsr166 1.9 * @return the last element, or <tt>null</tt> if this set is empty
117 : dl 1.1 */
118 : dl 1.3 E pollLast();
119 : dl 1.1
120 :     /**
121 : jsr166 1.10 * Returns an iterator over the elements in this set, in ascending order.
122 : jsr166 1.6 *
123 : jsr166 1.10 * @return an iterator over the elements in this set, in ascending order
124 :     */
125 :     Iterator<E> iterator();
126 :    
127 :     /**
128 :     * Returns an iterator over the elements in this set, in descending order.
129 :     *
130 :     * @return an iterator over the elements in this set, in descending order
131 : dl 1.1 */
132 :     Iterator<E> descendingIterator();
133 :    
134 :     /**
135 : dl 1.3 * Returns a view of the portion of this set whose elements range
136 :     * from <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
137 :     * exclusive. (If <tt>fromElement</tt> and <tt>toElement</tt> are
138 : jsr166 1.9 * equal, the returned set is empty.) The returned set is backed
139 :     * by this set, so changes in the returned set are reflected in
140 :     * this set, and vice-versa. The returned set supports all
141 :     * optional set operations that this set supports.
142 : dl 1.3 *
143 : jsr166 1.9 * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
144 :     * on an attempt to insert an element outside its range.
145 :     *
146 :     * @param fromElement low endpoint (inclusive) of the returned set
147 :     * @param toElement high endpoint (exclusive) of the returned set
148 : dl 1.1 * @return a view of the portion of this set whose elements range from
149 : jsr166 1.9 * <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive
150 : dl 1.1 * @throws ClassCastException if <tt>fromElement</tt> and
151 : jsr166 1.9 * <tt>toElement</tt> cannot be compared to one another using this
152 :     * set's comparator (or, if the set has no comparator, using
153 :     * natural ordering). Implementations may, but are not required
154 :     * to, throw this exception if <tt>fromElement</tt> or
155 :     * <tt>toElement</tt> cannot be compared to elements currently in
156 :     * the set.
157 :     * @throws NullPointerException if <tt>fromElement</tt> or
158 :     * <tt>toElement</tt> is null and this set does
159 :     * not permit null elements
160 : dl 1.1 * @throws IllegalArgumentException if <tt>fromElement</tt> is
161 : jsr166 1.9 * greater than <tt>toElement</tt>; or if this set itself
162 :     * has a restricted range, and <tt>fromElement</tt> or
163 :     * <tt>toElement</tt> lies outside the bounds of the range.
164 : dl 1.1 */
165 : dl 1.3 NavigableSet<E> navigableSubSet(E fromElement, E toElement);
166 : dl 1.1
167 :     /**
168 : dl 1.3 * Returns a view of the portion of this set whose elements are
169 : jsr166 1.9 * strictly less than <tt>toElement</tt>. The returned set is
170 :     * backed by this set, so changes in the returned set are
171 :     * reflected in this set, and vice-versa. The returned set
172 :     * supports all optional set operations that this set supports.
173 :     *
174 :     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
175 :     * on an attempt to insert an element outside its range.
176 :     *
177 :     * @param toElement high endpoint (exclusive) of the returned set
178 : dl 1.1 * @return a view of the portion of this set whose elements are strictly
179 : jsr166 1.9 * less than <tt>toElement</tt>
180 : dl 1.1 * @throws ClassCastException if <tt>toElement</tt> is not compatible
181 :     * with this set's comparator (or, if the set has no comparator,
182 : jsr166 1.9 * if <tt>toElement</tt> does not implement {@link Comparable}).
183 :     * Implementations may, but are not required to, throw this
184 :     * exception if <tt>toElement</tt> cannot be compared to elements
185 :     * currently in the set.
186 :     * @throws NullPointerException if <tt>toElement</tt> is null and
187 :     * this set does not permit null elements
188 :     * @throws IllegalArgumentException if this set itself has a
189 :     * restricted range, and <tt>toElement</tt> lies outside the
190 :     * bounds of the range
191 : dl 1.1 */
192 : dl 1.3 NavigableSet<E> navigableHeadSet(E toElement);
193 : dl 1.1
194 :     /**
195 :     * Returns a view of the portion of this set whose elements are
196 :     * greater than or equal to <tt>fromElement</tt>. The returned
197 : jsr166 1.9 * set is backed by this set, so changes in the returned set are
198 :     * reflected in this set, and vice-versa. The returned set
199 :     * supports all optional set operations that this set supports.
200 :     *
201 :     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
202 :     * on an attempt to insert an element outside its range.
203 :     *
204 :     * @param fromElement low endpoint (inclusive) of the returned set
205 :     * @return a view of the portion of this set whose elements are greater
206 :     * than or equal to <tt>fromElement</tt>
207 :     * @throws ClassCastException if <tt>fromElement</tt> is not compatible
208 :     * with this set's comparator (or, if the set has no comparator,
209 :     * if <tt>fromElement</tt> does not implement {@link Comparable}).
210 :     * Implementations may, but are not required to, throw this
211 :     * exception if <tt>fromElement</tt> cannot be compared to elements
212 :     * currently in the set.
213 :     * @throws NullPointerException if <tt>fromElement</tt> is null
214 :     * and this set does not permit null elements
215 :     * @throws IllegalArgumentException if this set itself has a
216 :     * restricted range, and <tt>fromElement</tt> lies outside the
217 :     * bounds of the range
218 : dl 1.1 */
219 : dl 1.3 NavigableSet<E> navigableTailSet(E fromElement);
220 : dl 1.1 }

Doug Lea
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