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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 :    
9 :     /**
10 :     * A {@link SortedSet} extended with navigation methods reporting
11 :     * closest matches for given search targets. Methods <tt>lower</tt>,
12 : jsr166 1.9 * <tt>floor</tt>, <tt>ceiling</tt>, and <tt>higher</tt> return elements
13 : dl 1.1 * respectively less than, less than or equal, greater than or equal,
14 : jsr166 1.9 * and greater than a given element, returning <tt>null</tt> if there is
15 :     * no such element. A <tt>NavigableSet</tt> may be viewed and traversed
16 : dl 1.1 * in either ascending or descending order. The <tt>Collection</tt>
17 :     * <tt>iterator</tt> method returns an ascending <tt>Iterator</tt> and
18 : jsr166 1.9 * the additional method <tt>descendingIterator</tt> returns a
19 : dl 1.1 * descending iterator. The performance of ascending traversals is
20 :     * likely to be faster than descending traversals. This interface
21 :     * additionally defines methods <tt>pollFirst</tt> and
22 : jsr166 1.9 * <tt>pollLast</tt> that return and remove the lowest and highest
23 :     * element, if one exists, else returning <tt>null</tt>.
24 : dl 1.4 * Methods <tt>navigableSubSet</tt>, <tt>navigableHeadSet</tt>, and
25 :     * <tt>navigableTailSet</tt> differ from the similarly named
26 :     * <tt>SortedSet</tt> methods only in that the returned sets
27 :     * are guaranteed to obey the <tt>NavigableSet</tt> interface.
28 : dl 1.1 *
29 :     * <p> The return values of navigation methods may be ambiguous in
30 :     * implementations that permit <tt>null</tt> elements. However, even
31 :     * in this case the result can be disambiguated by checking
32 :     * <tt>contains(null)</tt>. To avoid such issues, implementations of
33 : jsr166 1.9 * this interface are encouraged to <em>not</em> permit insertion of
34 : dl 1.1 * <tt>null</tt> elements. (Note that sorted sets of {@link
35 :     * Comparable} elements intrinsically do not permit <tt>null</tt>.)
36 :     *
37 : jsr166 1.8 * <p>This interface is a member of the
38 :     * <a href="{@docRoot}/../guide/collections/index.html">
39 :     * Java Collections Framework</a>.
40 :     *
41 : dl 1.1 * @author Doug Lea
42 :     * @param <E> the type of elements maintained by this set
43 : jsr166 1.7 * @since 1.6
44 : dl 1.1 */
45 :     public interface NavigableSet<E> extends SortedSet<E> {
46 :     /**
47 : jsr166 1.9 * Returns the greatest element in this set strictly less than the
48 :     * given element, or <tt>null</tt> if there is no such element.
49 : jsr166 1.6 *
50 : jsr166 1.5 * @param e the value to match
51 : jsr166 1.9 * @return the greatest element less than <tt>e</tt>,
52 :     * or <tt>null</tt> if there is no such element
53 :     * @throws ClassCastException if the specified element cannot be
54 :     * compared with the elements currently in the set
55 :     * @throws NullPointerException if the specified element is null
56 :     * and this set does not permit null elements
57 : dl 1.1 */
58 : jsr166 1.9 E lower(E e);
59 : dl 1.1
60 :     /**
61 : jsr166 1.9 * Returns the greatest element in this set less than or equal to
62 :     * the given element, or <tt>null</tt> if there is no such element.
63 : jsr166 1.6 *
64 : jsr166 1.5 * @param e the value to match
65 : jsr166 1.9 * @return the greatest element less than or equal to <tt>e</tt>,
66 :     * or <tt>null</tt> if there is no such element
67 :     * @throws ClassCastException if the specified element cannot be
68 :     * compared with the elements currently in the set
69 :     * @throws NullPointerException if the specified element is null
70 :     * and this set does not permit null elements
71 : dl 1.1 */
72 : jsr166 1.9 E floor(E e);
73 : dl 1.1
74 :     /**
75 : jsr166 1.9 * Returns the least element in this set greater than or equal to
76 :     * the given element, or <tt>null</tt> if there is no such element.
77 : jsr166 1.6 *
78 : jsr166 1.5 * @param e the value to match
79 : jsr166 1.9 * @return the least element greater than or equal to <tt>e</tt>,
80 :     * or <tt>null</tt> if there is no such element
81 :     * @throws ClassCastException if the specified element cannot be
82 :     * compared with the elements currently in the set
83 :     * @throws NullPointerException if the specified element is null
84 :     * and this set does not permit null elements
85 : dl 1.1 */
86 : jsr166 1.9 E ceiling(E e);
87 : dl 1.1
88 :     /**
89 : jsr166 1.9 * Returns the least element in this set strictly greater than the
90 :     * given element, or <tt>null</tt> if there is no such element.
91 : jsr166 1.6 *
92 : jsr166 1.5 * @param e the value to match
93 : jsr166 1.9 * @return the least element greater than <tt>e</tt>,
94 :     * or <tt>null</tt> if there is no such element
95 :     * @throws ClassCastException if the specified element cannot be
96 :     * compared with the elements currently in the set
97 :     * @throws NullPointerException if the specified element is null
98 :     * and this set does not permit null elements
99 : dl 1.1 */
100 : jsr166 1.5 E higher(E e);
101 : dl 1.1
102 :     /**
103 :     * Retrieves and removes the first (lowest) element.
104 :     *
105 : jsr166 1.9 * @return the first element, or <tt>null</tt> if this set is empty
106 : dl 1.1 */
107 : dl 1.3 E pollFirst();
108 : dl 1.1
109 :     /**
110 :     * Retrieves and removes the last (highest) element.
111 :     *
112 : jsr166 1.9 * @return the last element, or <tt>null</tt> if this set is empty
113 : dl 1.1 */
114 : dl 1.3 E pollLast();
115 : dl 1.1
116 :     /**
117 : jsr166 1.9 * Returns an iterator over the elements in this set, in
118 : jsr166 1.6 * descending order.
119 :     *
120 : jsr166 1.9 * @return an <tt>Iterator</tt> over the elements in this set
121 : dl 1.1 */
122 :     Iterator<E> descendingIterator();
123 :    
124 :     /**
125 : dl 1.3 * Returns a view of the portion of this set whose elements range
126 :     * from <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
127 :     * exclusive. (If <tt>fromElement</tt> and <tt>toElement</tt> are
128 : jsr166 1.9 * equal, the returned set is empty.) The returned set is backed
129 :     * by this set, so changes in the returned set are reflected in
130 :     * this set, and vice-versa. The returned set supports all
131 :     * optional set operations that this set supports.
132 : dl 1.3 *
133 : jsr166 1.9 * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
134 :     * on an attempt to insert an element outside its range.
135 :     *
136 :     * @param fromElement low endpoint (inclusive) of the returned set
137 :     * @param toElement high endpoint (exclusive) of the returned set
138 : dl 1.1 * @return a view of the portion of this set whose elements range from
139 : jsr166 1.9 * <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive
140 : dl 1.1 * @throws ClassCastException if <tt>fromElement</tt> and
141 : jsr166 1.9 * <tt>toElement</tt> cannot be compared to one another using this
142 :     * set's comparator (or, if the set has no comparator, using
143 :     * natural ordering). Implementations may, but are not required
144 :     * to, throw this exception if <tt>fromElement</tt> or
145 :     * <tt>toElement</tt> cannot be compared to elements currently in
146 :     * the set.
147 :     * @throws NullPointerException if <tt>fromElement</tt> or
148 :     * <tt>toElement</tt> is null and this set does
149 :     * not permit null elements
150 : dl 1.1 * @throws IllegalArgumentException if <tt>fromElement</tt> is
151 : jsr166 1.9 * greater than <tt>toElement</tt>; or if this set itself
152 :     * has a restricted range, and <tt>fromElement</tt> or
153 :     * <tt>toElement</tt> lies outside the bounds of the range.
154 : dl 1.1 */
155 : dl 1.3 NavigableSet<E> navigableSubSet(E fromElement, E toElement);
156 : dl 1.1
157 :     /**
158 : dl 1.3 * Returns a view of the portion of this set whose elements are
159 : jsr166 1.9 * strictly less than <tt>toElement</tt>. The returned set is
160 :     * backed by this set, so changes in the returned set are
161 :     * reflected in this set, and vice-versa. The returned set
162 :     * supports all optional set operations that this set supports.
163 :     *
164 :     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
165 :     * on an attempt to insert an element outside its range.
166 :     *
167 :     * @param toElement high endpoint (exclusive) of the returned set
168 : dl 1.1 * @return a view of the portion of this set whose elements are strictly
169 : jsr166 1.9 * less than <tt>toElement</tt>
170 : dl 1.1 * @throws ClassCastException if <tt>toElement</tt> is not compatible
171 :     * with this set's comparator (or, if the set has no comparator,
172 : jsr166 1.9 * if <tt>toElement</tt> does not implement {@link Comparable}).
173 :     * Implementations may, but are not required to, throw this
174 :     * exception if <tt>toElement</tt> cannot be compared to elements
175 :     * currently in the set.
176 :     * @throws NullPointerException if <tt>toElement</tt> is null and
177 :     * this set does not permit null elements
178 :     * @throws IllegalArgumentException if this set itself has a
179 :     * restricted range, and <tt>toElement</tt> lies outside the
180 :     * bounds of the range
181 : dl 1.1 */
182 : dl 1.3 NavigableSet<E> navigableHeadSet(E toElement);
183 : dl 1.1
184 :     /**
185 :     * Returns a view of the portion of this set whose elements are
186 :     * greater than or equal to <tt>fromElement</tt>. The returned
187 : jsr166 1.9 * set is backed by this set, so changes in the returned set are
188 :     * reflected in this set, and vice-versa. The returned set
189 :     * supports all optional set operations that this set supports.
190 :     *
191 :     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
192 :     * on an attempt to insert an element outside its range.
193 :     *
194 :     * @param fromElement low endpoint (inclusive) of the returned set
195 :     * @return a view of the portion of this set whose elements are greater
196 :     * than or equal to <tt>fromElement</tt>
197 :     * @throws ClassCastException if <tt>fromElement</tt> is not compatible
198 :     * with this set's comparator (or, if the set has no comparator,
199 :     * if <tt>fromElement</tt> does not implement {@link Comparable}).
200 :     * Implementations may, but are not required to, throw this
201 :     * exception if <tt>fromElement</tt> cannot be compared to elements
202 :     * currently in the set.
203 :     * @throws NullPointerException if <tt>fromElement</tt> is null
204 :     * and this set does not permit null elements
205 :     * @throws IllegalArgumentException if this set itself has a
206 :     * restricted range, and <tt>fromElement</tt> lies outside the
207 :     * bounds of the range
208 : dl 1.1 */
209 : dl 1.3 NavigableSet<E> navigableTailSet(E fromElement);
210 : dl 1.1 }

Doug Lea
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