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root/jsr166/jsr166/src/main/java/util/NavigableSet.java
Revision: 1.11
Committed: Mon Jul 18 19:32:38 2005 UTC (18 years, 10 months ago) by dl
Branch: MAIN
Changes since 1.10: +4 -1 lines
Log Message: 
Clarify submap specs

File Contents

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