src/jsr166x/NavigableMap.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 jsr166x;

import java.util.*;

/**
 * A {@link SortedMap} extended with navigation methods returning
 * key-value pairs holding the closest matches for given search
 * targets. Methods <tt>lowerEntry</tt>, <tt>floorEntry</tt>,
 * <tt>ceilingEntry</tt>, and <tt>higherEntry</tt> return
 * <tt>Map.Entry</tt> objects associated with keys respectively less
 * than, less than or equal, greater than or equal, and greater than a
 * given key, returning <tt>null</tt> if there is no such key.  These
 * methods are designed for locating, not traversing entries. To
 * traverse, use view iterators and/or <tt>submap</tt>. This interface
 * additionally defines methods <tt>firstEntry</tt>,
 * <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and
 * <tt>pollLastEntry</tt> that return and/or remove the least and
 * greatest mappings, if any exist, else returning <tt>null</tt>.
 *
 * <p> Implementations of these methods are expected to return
 * <tt>Map.Entry</tt> pairs representing snapshots of mappings at the
 * time they were produced, and thus generally do <em>not</em> support
 * the optional <tt>Entry.setValue</tt> method. Note however that it
 * is possible to change mappings in the associated map using method
 * <tt>put</tt>.
 *
 * @author Doug Lea
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values 
 */
public interface NavigableMap<K,V> extends SortedMap<K,V> {
    /**
     * Returns a key-value mapping associated with the least key
     * greater than or equal to the given key, or <tt>null</tt> if there is
     * no such entry. 
     * 
     * @param key the key.
     * @return an Entry associated with ceiling of given key, or <tt>null</tt>
     * if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> ceilingEntry(K key);

    /**
     * Returns a key-value mapping associated with the greatest
     * key strictly less than the given key, or <tt>null</tt> if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry with greatest key less than the given
     * key, or <tt>null</tt> if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> lowerEntry(K key);

    /**
     * Returns a key-value mapping associated with the greatest
     * key less than or equal to the given key, or <tt>null</tt> if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry associated with floor of given key, or <tt>null</tt>
     * if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> floorEntry(K key);

    /**
     * Returns a key-value mapping associated with the least
     * key strictly greater than the given key, or <tt>null</tt> if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry with least key greater than the given key, or
     * <tt>null</tt> if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> higherEntry(K key);

    /**
     * Returns a key-value mapping associated with the least
     * key in this map, or <tt>null</tt> if the map is empty.
     * 
     * @return an Entry with least key, or <tt>null</tt> 
     * if the map is empty.
     */
    public Map.Entry<K,V> firstEntry();

    /**
     * Returns a key-value mapping associated with the greatest
     * key in this map, or <tt>null</tt> if the map is empty.
     * 
     * @return an Entry with greatest key, or <tt>null</tt>
     * if the map is empty.
     */
    public Map.Entry<K,V> lastEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the least key in this map, or <tt>null</tt> if the map is empty.
     * 
     * @return the removed first entry of this map, or <tt>null</tt>
     * if the map is empty.
     */
    public Map.Entry<K,V> pollFirstEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the greatest key in this map, or <tt>null</tt> if the map is empty.
     * 
     * @return the removed last entry of this map, or <tt>null</tt>
     * if the map is empty.
     */
    public Map.Entry<K,V> pollLastEntry();

    /**
     * Returns a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.  (If
     * <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned sorted map
     * is empty.)  The returned sorted map is backed by this map, so changes
     * in the returned sorted map are reflected in this map, and vice-versa.

     * @param fromKey low endpoint (inclusive) of the subMap.
     * @param toKey high endpoint (exclusive) of the subMap.
     *
     * @return a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
     *
     * @throws ClassCastException if <tt>fromKey</tt> and
     * <tt>toKey</tt> cannot be compared to one another using this
     * map's comparator (or, if the map has no comparator, using
     * natural ordering).
     * @throws IllegalArgumentException if <tt>fromKey</tt> is greater
     * than <tt>toKey</tt>.
     * @throws NullPointerException if <tt>fromKey</tt> or
     * <tt>toKey</tt> is <tt>null</tt> and this map does not support
     * <tt>null</tt> keys.
     */
    public NavigableMap<K,V> subMap(K fromKey, K toKey);

    /**
     * Returns a view of the portion of this map whose keys are strictly less
     * than <tt>toKey</tt>.  The returned sorted map is backed by this map, so
     * changes in the returned sorted map are reflected in this map, and
     * vice-versa.  
     * @param toKey high endpoint (exclusive) of the headMap.
     * @return a view of the portion of this map whose keys are strictly
     *                less than <tt>toKey</tt>.
     *
     * @throws ClassCastException if <tt>toKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    public NavigableMap<K,V> headMap(K toKey);

    /**
     * Returns a view of the portion of this map whose keys are
     * greater than or equal to <tt>fromKey</tt>.  The returned sorted
     * map is backed by this map, so changes in the returned sorted
     * map are reflected in this map, and vice-versa.
     * @param fromKey low endpoint (inclusive) of the tailMap.
     * @return a view of the portion of this map whose keys are greater
     *                than or equal to <tt>fromKey</tt>.
     * @throws ClassCastException if <tt>fromKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    public NavigableMap<K,V>  tailMap(K fromKey);
}
Revision:	1.2
Committed:	Tue Sep 7 11:37:57 2004 UTC (19 years, 8 months ago) by dl
Branch:	MAIN
Changes since 1.1:	+29 -29 lines
Log Message:	Javadoc improvements
#	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 jsr166x;
8
9			import java.util.*;
10
11			/**
12	dl	1.2	* A {@link SortedMap} extended with navigation methods returning
13			* key-value pairs holding the closest matches for given search
14			* targets. Methods <tt>lowerEntry</tt>, <tt>floorEntry</tt>,
15			* <tt>ceilingEntry</tt>, and <tt>higherEntry</tt> return
16			* <tt>Map.Entry</tt> objects associated with keys respectively less
17			* than, less than or equal, greater than or equal, and greater than a
18			* given key, returning <tt>null</tt> if there is no such key. These
19			* methods are designed for locating, not traversing entries. To
20			* traverse, use view iterators and/or <tt>submap</tt>. This interface
21			* additionally defines methods <tt>firstEntry</tt>,
22			* <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and
23			* <tt>pollLastEntry</tt> that return and/or remove the least and
24			* greatest mappings, if any exist, else returning <tt>null</tt>.
25	dl	1.1	*
26			* <p> Implementations of these methods are expected to return
27			* <tt>Map.Entry</tt> pairs representing snapshots of mappings at the
28			* time they were produced, and thus generally do <em>not</em> support
29			* the optional <tt>Entry.setValue</tt> method. Note however that it
30			* is possible to change mappings in the associated map using method
31			* <tt>put</tt>.
32			*
33			* @author Doug Lea
34			* @param <K> the type of keys maintained by this map
35			* @param <V> the type of mapped values
36			*/
37			public interface NavigableMap<K,V> extends SortedMap<K,V> {
38			/**
39			* Returns a key-value mapping associated with the least key
40	dl	1.2	* greater than or equal to the given key, or <tt>null</tt> if there is
41	dl	1.1	* no such entry.
42			*
43			* @param key the key.
44	dl	1.2	* @return an Entry associated with ceiling of given key, or <tt>null</tt>
45	dl	1.1	* if there is no such Entry.
46			* @throws ClassCastException if key cannot be compared with the keys
47			* currently in the map.
48			* @throws NullPointerException if key is <tt>null</tt> and this map
49			* does not support <tt>null</tt> keys.
50			*/
51			public Map.Entry<K,V> ceilingEntry(K key);
52
53			/**
54			* Returns a key-value mapping associated with the greatest
55	dl	1.2	* key strictly less than the given key, or <tt>null</tt> if there is no
56	dl	1.1	* such entry.
57			*
58			* @param key the key.
59			* @return an Entry with greatest key less than the given
60	dl	1.2	* key, or <tt>null</tt> if there is no such Entry.
61	dl	1.1	* @throws ClassCastException if key cannot be compared with the keys
62			* currently in the map.
63			* @throws NullPointerException if key is <tt>null</tt> and this map
64			* does not support <tt>null</tt> keys.
65			*/
66			public Map.Entry<K,V> lowerEntry(K key);
67
68			/**
69			* Returns a key-value mapping associated with the greatest
70	dl	1.2	* key less than or equal to the given key, or <tt>null</tt> if there is no
71	dl	1.1	* such entry.
72			*
73			* @param key the key.
74	dl	1.2	* @return an Entry associated with floor of given key, or <tt>null</tt>
75	dl	1.1	* if there is no such Entry.
76			* @throws ClassCastException if key cannot be compared with the keys
77			* currently in the map.
78			* @throws NullPointerException if key is <tt>null</tt> and this map
79			* does not support <tt>null</tt> keys.
80			*/
81			public Map.Entry<K,V> floorEntry(K key);
82
83			/**
84			* Returns a key-value mapping associated with the least
85	dl	1.2	* key strictly greater than the given key, or <tt>null</tt> if there is no
86	dl	1.1	* such entry.
87			*
88			* @param key the key.
89			* @return an Entry with least key greater than the given key, or
90	dl	1.2	* <tt>null</tt> if there is no such Entry.
91	dl	1.1	* @throws ClassCastException if key cannot be compared with the keys
92			* currently in the map.
93			* @throws NullPointerException if key is <tt>null</tt> and this map
94			* does not support <tt>null</tt> keys.
95			*/
96			public Map.Entry<K,V> higherEntry(K key);
97
98			/**
99			* Returns a key-value mapping associated with the least
100	dl	1.2	* key in this map, or <tt>null</tt> if the map is empty.
101	dl	1.1	*
102	dl	1.2	* @return an Entry with least key, or <tt>null</tt>
103	dl	1.1	* if the map is empty.
104			*/
105			public Map.Entry<K,V> firstEntry();
106
107			/**
108			* Returns a key-value mapping associated with the greatest
109	dl	1.2	* key in this map, or <tt>null</tt> if the map is empty.
110	dl	1.1	*
111	dl	1.2	* @return an Entry with greatest key, or <tt>null</tt>
112	dl	1.1	* if the map is empty.
113			*/
114			public Map.Entry<K,V> lastEntry();
115
116			/**
117			* Removes and returns a key-value mapping associated with
118	dl	1.2	* the least key in this map, or <tt>null</tt> if the map is empty.
119	dl	1.1	*
120	dl	1.2	* @return the removed first entry of this map, or <tt>null</tt>
121	dl	1.1	* if the map is empty.
122			*/
123			public Map.Entry<K,V> pollFirstEntry();
124
125			/**
126			* Removes and returns a key-value mapping associated with
127	dl	1.2	* the greatest key in this map, or <tt>null</tt> if the map is empty.
128	dl	1.1	*
129	dl	1.2	* @return the removed last entry of this map, or <tt>null</tt>
130	dl	1.1	* if the map is empty.
131			*/
132			public Map.Entry<K,V> pollLastEntry();
133
134			/**
135			* Returns a view of the portion of this map whose keys range from
136			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If
137			* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned sorted map
138			* is empty.) The returned sorted map is backed by this map, so changes
139			* in the returned sorted map are reflected in this map, and vice-versa.
140
141			* @param fromKey low endpoint (inclusive) of the subMap.
142			* @param toKey high endpoint (exclusive) of the subMap.
143			*
144			* @return a view of the portion of this map whose keys range from
145			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
146			*
147			* @throws ClassCastException if <tt>fromKey</tt> and
148			* <tt>toKey</tt> cannot be compared to one another using this
149			* map's comparator (or, if the map has no comparator, using
150			* natural ordering).
151			* @throws IllegalArgumentException if <tt>fromKey</tt> is greater
152			* than <tt>toKey</tt>.
153			* @throws NullPointerException if <tt>fromKey</tt> or
154			* <tt>toKey</tt> is <tt>null</tt> and this map does not support
155			* <tt>null</tt> keys.
156			*/
157			public NavigableMap<K,V> subMap(K fromKey, K toKey);
158
159			/**
160			* Returns a view of the portion of this map whose keys are strictly less
161			* than <tt>toKey</tt>. The returned sorted map is backed by this map, so
162			* changes in the returned sorted map are reflected in this map, and
163			* vice-versa.
164			* @param toKey high endpoint (exclusive) of the headMap.
165			* @return a view of the portion of this map whose keys are strictly
166			* less than <tt>toKey</tt>.
167			*
168			* @throws ClassCastException if <tt>toKey</tt> is not compatible
169			* with this map's comparator (or, if the map has no comparator,
170			* if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
171			* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
172			* and this map does not support <tt>null</tt> keys.
173			*/
174			public NavigableMap<K,V> headMap(K toKey);
175
176			/**
177			* Returns a view of the portion of this map whose keys are
178			* greater than or equal to <tt>fromKey</tt>. The returned sorted
179			* map is backed by this map, so changes in the returned sorted
180			* map are reflected in this map, and vice-versa.
181			* @param fromKey low endpoint (inclusive) of the tailMap.
182			* @return a view of the portion of this map whose keys are greater
183			* than or equal to <tt>fromKey</tt>.
184			* @throws ClassCastException if <tt>fromKey</tt> is not compatible
185			* with this map's comparator (or, if the map has no comparator,
186			* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
187			* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
188			* and this map does not support <tt>null</tt> keys.
189			*/
190			public NavigableMap<K,V> tailMap(K fromKey);
191			}