java/util/NavigableSet.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

package java.util;

/**
 * A {@link SortedSet} extended with navigation methods reporting
 * closest matches for given search targets. Methods <tt>lower</tt>,
 * <tt>floor</tt>, <tt>ceiling</tt>, and <tt>higher</tt> return elements
 * respectively less than, less than or equal, greater than or equal,
 * and greater than a given element, returning <tt>null</tt> if there is
 * no such element.  A <tt>NavigableSet</tt> may be viewed and traversed
 * in either ascending or descending order.  The <tt>Collection</tt>
 * <tt>iterator</tt> method returns an ascending <tt>Iterator</tt> and
 * the additional method <tt>descendingIterator</tt> returns a
 * descending iterator. The performance of ascending traversals is
 * likely to be faster than descending traversals.  This interface
 * additionally defines methods <tt>pollFirst</tt> and
 * <tt>pollLast</tt> that return and remove the lowest and highest
 * element, if one exists, else returning <tt>null</tt>.
 * Methods <tt>navigableSubSet</tt>, <tt>navigableHeadSet</tt>, and
 * <tt>navigableTailSet</tt> differ from the similarly named
 * <tt>SortedSet</tt> methods only in that the returned sets
 * are guaranteed to obey the <tt>NavigableSet</tt> interface.
 *
 * <p> The return values of navigation methods may be ambiguous in
 * implementations that permit <tt>null</tt> elements. However, even
 * in this case the result can be disambiguated by checking
 * <tt>contains(null)</tt>. To avoid such issues, implementations of
 * this interface are encouraged to <em>not</em> permit insertion of
 * <tt>null</tt> elements. (Note that sorted sets of {@link
 * Comparable} elements intrinsically do not permit <tt>null</tt>.)
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../guide/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @author Doug Lea
 * @param <E> the type of elements maintained by this set
 * @since 1.6
 */
public interface NavigableSet<E> extends SortedSet<E> {
    /**
     * Returns the greatest element in this set strictly less than the
     * given element, or <tt>null</tt> if there is no such element.
     *
     * @param e the value to match
     * @return the greatest element less than <tt>e</tt>,
     *         or <tt>null</tt> if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E lower(E e);

    /**
     * Returns the greatest element in this set less than or equal to
     * the given element, or <tt>null</tt> if there is no such element.
     *
     * @param e the value to match
     * @return the greatest element less than or equal to <tt>e</tt>,
     *         or <tt>null</tt> if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E floor(E e);

    /**
     * Returns the least element in this set greater than or equal to
     * the given element, or <tt>null</tt> if there is no such element.
     *
     * @param e the value to match
     * @return the least element greater than or equal to <tt>e</tt>,
     *         or <tt>null</tt> if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E ceiling(E e);

    /**
     * Returns the least element in this set strictly greater than the
     * given element, or <tt>null</tt> if there is no such element.
     *
     * @param e the value to match
     * @return the least element greater than <tt>e</tt>,
     *         or <tt>null</tt> if there is no such element
     * @throws ClassCastException if the specified element cannot be
     *         compared with the elements currently in the set
     * @throws NullPointerException if the specified element is null
     *         and this set does not permit null elements
     */
    E higher(E e);

    /**
     * Retrieves and removes the first (lowest) element.
     *
     * @return the first element, or <tt>null</tt> if this set is empty
     */
    E pollFirst();

    /**
     * Retrieves and removes the last (highest) element.
     *
     * @return the last element, or <tt>null</tt> if this set is empty
     */
    E pollLast();

    /**
     * Returns an iterator over the elements in this set, in
     * descending order.
     *
     * @return an <tt>Iterator</tt> over the elements in this set
     */
    Iterator<E> descendingIterator();

    /**
     * Returns a view of the portion of this set whose elements range
     * from <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
     * exclusive.  (If <tt>fromElement</tt> and <tt>toElement</tt> are
     * equal, the returned set is empty.)  The returned set is backed
     * by this set, so changes in the returned set are reflected in
     * this set, and vice-versa.  The returned set supports all
     * optional set operations that this set supports.
     *
     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
     * on an attempt to insert an element outside its range.
     *
     * @param fromElement low endpoint (inclusive) of the returned set
     * @param toElement high endpoint (exclusive) of the returned set
     * @return a view of the portion of this set whose elements range from
     *         <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive
     * @throws ClassCastException if <tt>fromElement</tt> and
     *         <tt>toElement</tt> cannot be compared to one another using this
     *         set's comparator (or, if the set has no comparator, using
     *         natural ordering).  Implementations may, but are not required
     *         to, throw this exception if <tt>fromElement</tt> or
     *         <tt>toElement</tt> cannot be compared to elements currently in
     *         the set.
     * @throws NullPointerException if <tt>fromElement</tt> or
     *         <tt>toElement</tt> is null and this set does
     *         not permit null elements
     * @throws IllegalArgumentException if <tt>fromElement</tt> is
     *         greater than <tt>toElement</tt>; or if this set itself
     *         has a restricted range, and <tt>fromElement</tt> or
     *         <tt>toElement</tt> lies outside the bounds of the range.
     */
    NavigableSet<E> navigableSubSet(E fromElement, E toElement);

    /**
     * Returns a view of the portion of this set whose elements are
     * strictly less than <tt>toElement</tt>.  The returned set is
     * backed by this set, so changes in the returned set are
     * reflected in this set, and vice-versa.  The returned set
     * supports all optional set operations that this set supports.
     *
     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
     * on an attempt to insert an element outside its range.
     *
     * @param toElement high endpoint (exclusive) of the returned set
     * @return a view of the portion of this set whose elements are strictly
     *         less than <tt>toElement</tt>
     * @throws ClassCastException if <tt>toElement</tt> is not compatible
     *         with this set's comparator (or, if the set has no comparator,
     *         if <tt>toElement</tt> does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if <tt>toElement</tt> cannot be compared to elements
     *         currently in the set.
     * @throws NullPointerException if <tt>toElement</tt> is null and
     *         this set does not permit null elements
     * @throws IllegalArgumentException if this set itself has a
     *         restricted range, and <tt>toElement</tt> lies outside the
     *         bounds of the range
     */
    NavigableSet<E> navigableHeadSet(E toElement);

    /**
     * Returns a view of the portion of this set whose elements are
     * greater than or equal to <tt>fromElement</tt>.  The returned
     * set is backed by this set, so changes in the returned set are
     * reflected in this set, and vice-versa.  The returned set
     * supports all optional set operations that this set supports.
     *
     * <p>The returned set will throw an <tt>IllegalArgumentException</tt>
     * on an attempt to insert an element outside its range.
     *
     * @param fromElement low endpoint (inclusive) of the returned set
     * @return a view of the portion of this set whose elements are greater
     *         than or equal to <tt>fromElement</tt>
     * @throws ClassCastException if <tt>fromElement</tt> is not compatible
     *         with this set's comparator (or, if the set has no comparator,
     *         if <tt>fromElement</tt> does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if <tt>fromElement</tt> cannot be compared to elements
     *         currently in the set.
     * @throws NullPointerException if <tt>fromElement</tt> is null
     *         and this set does not permit null elements
     * @throws IllegalArgumentException if this set itself has a
     *         restricted range, and <tt>fromElement</tt> lies outside the
     *         bounds of the range
     */
    NavigableSet<E> navigableTailSet(E fromElement);
}
Revision:	1.9
Committed:	Mon May 16 06:27:52 2005 UTC (19 years ago) by jsr166
Branch:	MAIN
Changes since 1.8:	+108 -79 lines
Log Message:	doc fixes
#	Content
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	* <tt>floor</tt>, <tt>ceiling</tt>, and <tt>higher</tt> return elements
13	* respectively less than, less than or equal, greater than or equal,
14	* 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	* in either ascending or descending order. The <tt>Collection</tt>
17	* <tt>iterator</tt> method returns an ascending <tt>Iterator</tt> and
18	* the additional method <tt>descendingIterator</tt> returns a
19	* 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	* <tt>pollLast</tt> that return and remove the lowest and highest
23	* element, if one exists, else returning <tt>null</tt>.
24	* 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	*
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	* this interface are encouraged to <em>not</em> permit insertion of
34	* <tt>null</tt> elements. (Note that sorted sets of {@link
35	* Comparable} elements intrinsically do not permit <tt>null</tt>.)
36	*
37	* <p>This interface is a member of the
38	* <a href="{@docRoot}/../guide/collections/index.html">
39	* Java Collections Framework</a>.
40	*
41	* @author Doug Lea
42	* @param <E> the type of elements maintained by this set
43	* @since 1.6
44	*/
45	public interface NavigableSet<E> extends SortedSet<E> {
46	/**
47	* 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	*
50	* @param e the value to match
51	* @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	*/
58	E lower(E e);
59
60	/**
61	* 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	*
64	* @param e the value to match
65	* @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	*/
72	E floor(E e);
73
74	/**
75	* 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	*
78	* @param e the value to match
79	* @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	*/
86	E ceiling(E e);
87
88	/**
89	* 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	*
92	* @param e the value to match
93	* @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	*/
100	E higher(E e);
101
102	/**
103	* Retrieves and removes the first (lowest) element.
104	*
105	* @return the first element, or <tt>null</tt> if this set is empty
106	*/
107	E pollFirst();
108
109	/**
110	* Retrieves and removes the last (highest) element.
111	*
112	* @return the last element, or <tt>null</tt> if this set is empty
113	*/
114	E pollLast();
115
116	/**
117	* Returns an iterator over the elements in this set, in
118	* descending order.
119	*
120	* @return an <tt>Iterator</tt> over the elements in this set
121	*/
122	Iterator<E> descendingIterator();
123
124	/**
125	* 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	* 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	*
133	* <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	* @return a view of the portion of this set whose elements range from
139	* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive
140	* @throws ClassCastException if <tt>fromElement</tt> and
141	* <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	* @throws IllegalArgumentException if <tt>fromElement</tt> is
151	* 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	*/
155	NavigableSet<E> navigableSubSet(E fromElement, E toElement);
156
157	/**
158	* Returns a view of the portion of this set whose elements are
159	* 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	* @return a view of the portion of this set whose elements are strictly
169	* less than <tt>toElement</tt>
170	* @throws ClassCastException if <tt>toElement</tt> is not compatible
171	* with this set's comparator (or, if the set has no comparator,
172	* 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	*/
182	NavigableSet<E> navigableHeadSet(E toElement);
183
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	* 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	*/
209	NavigableSet<E> navigableTailSet(E fromElement);
210	}