| 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 |
* 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. |
| 19 |
* Similarly, methods <tt>lowerKey</tt>, <tt>floorKey</tt>, |
| 20 |
* <tt>ceilingKey</tt>, and <tt>higherKey</tt> return only the |
| 21 |
* associated keys. All of these methods are designed for locating, |
| 22 |
* not traversing entries. |
| 23 |
* |
| 24 |
* <p>A <tt>NavigableMap</tt> may be viewed and traversed in either |
| 25 |
* ascending or descending key order. The <tt>Map</tt> methods |
| 26 |
* <tt>keySet</tt> and <tt>entrySet</tt>) return ascending views, and |
| 27 |
* the additional methods <tt>descendingKeySet</tt> and |
| 28 |
* <tt>descendingEntrySet</tt>) return descending views. The |
| 29 |
* performance of ascending traversals is likely to be faster than |
| 30 |
* descending traversals. Notice that it is possible to perform |
| 31 |
* subrannge traversals in either direction using <tt>SubMap</tt>. |
| 32 |
* |
| 33 |
* <p>This interface additionally defines methods <tt>firstEntry</tt>, |
| 34 |
* <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and |
| 35 |
* <tt>pollLastEntry</tt> that return and/or remove the least and |
| 36 |
* greatest mappings, if any exist, else returning <tt>null</tt>. |
| 37 |
* |
| 38 |
* <p> Implementations of entry-returning methods are expected to |
| 39 |
* return <tt>Map.Entry</tt> pairs representing snapshots of mappings |
| 40 |
* at the time they were produced, and thus generally do <em>not</em> |
| 41 |
* support the optional <tt>Entry.setValue</tt> method. Note however |
| 42 |
* that it is possible to change mappings in the associated map using |
| 43 |
* method <tt>put</tt>. |
| 44 |
* |
| 45 |
* @author Doug Lea |
| 46 |
* @param <K> the type of keys maintained by this map |
| 47 |
* @param <V> the type of mapped values |
| 48 |
*/ |
| 49 |
public interface NavigableMap<K,V> extends SortedMap<K,V> { |
| 50 |
/** |
| 51 |
* Returns a key-value mapping associated with the least key |
| 52 |
* greater than or equal to the given key, or <tt>null</tt> if there is |
| 53 |
* no such entry. |
| 54 |
* |
| 55 |
* @param key the key. |
| 56 |
* @return an Entry associated with ceiling of given key, or <tt>null</tt> |
| 57 |
* if there is no such Entry. |
| 58 |
* @throws ClassCastException if key cannot be compared with the keys |
| 59 |
* currently in the map. |
| 60 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 61 |
* does not support <tt>null</tt> keys. |
| 62 |
*/ |
| 63 |
public Map.Entry<K,V> ceilingEntry(K key); |
| 64 |
|
| 65 |
/** |
| 66 |
* Returns least key greater than or equal to the given key, or |
| 67 |
* <tt>null</tt> if there is no such key. |
| 68 |
* |
| 69 |
* @param key the key. |
| 70 |
* @return the ceiling key, or <tt>null</tt> |
| 71 |
* if there is no such key. |
| 72 |
* @throws ClassCastException if key cannot be compared with the keys |
| 73 |
* currently in the map. |
| 74 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 75 |
* does not support <tt>null</tt> keys. |
| 76 |
*/ |
| 77 |
public K ceilingKey(K key); |
| 78 |
|
| 79 |
/** |
| 80 |
* Returns a key-value mapping associated with the greatest |
| 81 |
* key strictly less than the given key, or <tt>null</tt> if there is no |
| 82 |
* such entry. |
| 83 |
* |
| 84 |
* @param key the key. |
| 85 |
* @return an Entry with greatest key less than the given |
| 86 |
* key, or <tt>null</tt> if there is no such Entry. |
| 87 |
* @throws ClassCastException if key cannot be compared with the keys |
| 88 |
* currently in the map. |
| 89 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 90 |
* does not support <tt>null</tt> keys. |
| 91 |
*/ |
| 92 |
public Map.Entry<K,V> lowerEntry(K key); |
| 93 |
|
| 94 |
/** |
| 95 |
* Returns the greatest key strictly less than the given key, or |
| 96 |
* <tt>null</tt> if there is no such key. |
| 97 |
* |
| 98 |
* @param key the key. |
| 99 |
* @return the greatest key less than the given |
| 100 |
* key, or <tt>null</tt> if there is no such key. |
| 101 |
* @throws ClassCastException if key cannot be compared with the keys |
| 102 |
* currently in the map. |
| 103 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 104 |
* does not support <tt>null</tt> keys. |
| 105 |
*/ |
| 106 |
public K lowerKey(K key); |
| 107 |
|
| 108 |
/** |
| 109 |
* Returns a key-value mapping associated with the greatest key |
| 110 |
* less than or equal to the given key, or <tt>null</tt> if there |
| 111 |
* is no such entry. |
| 112 |
* |
| 113 |
* @param key the key. |
| 114 |
* @return an Entry associated with floor of given key, or <tt>null</tt> |
| 115 |
* if there is no such Entry. |
| 116 |
* @throws ClassCastException if key cannot be compared with the keys |
| 117 |
* currently in the map. |
| 118 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 119 |
* does not support <tt>null</tt> keys. |
| 120 |
*/ |
| 121 |
public Map.Entry<K,V> floorEntry(K key); |
| 122 |
|
| 123 |
/** |
| 124 |
* Returns the greatest key |
| 125 |
* less than or equal to the given key, or <tt>null</tt> if there |
| 126 |
* is no such key. |
| 127 |
* |
| 128 |
* @param key the key. |
| 129 |
* @return the floor of given key, or <tt>null</tt> if there is no |
| 130 |
* such key. |
| 131 |
* @throws ClassCastException if key cannot be compared with the keys |
| 132 |
* currently in the map. |
| 133 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 134 |
* does not support <tt>null</tt> keys. |
| 135 |
*/ |
| 136 |
public K floorKey(K key); |
| 137 |
|
| 138 |
/** |
| 139 |
* Returns a key-value mapping associated with the least key |
| 140 |
* strictly greater than the given key, or <tt>null</tt> if there |
| 141 |
* is no such entry. |
| 142 |
* |
| 143 |
* @param key the key. |
| 144 |
* @return an Entry with least key greater than the given key, or |
| 145 |
* <tt>null</tt> if there is no such Entry. |
| 146 |
* @throws ClassCastException if key cannot be compared with the keys |
| 147 |
* currently in the map. |
| 148 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 149 |
* does not support <tt>null</tt> keys. |
| 150 |
*/ |
| 151 |
public Map.Entry<K,V> higherEntry(K key); |
| 152 |
|
| 153 |
/** |
| 154 |
* Returns the least key strictly greater than the given key, or |
| 155 |
* <tt>null</tt> if there is no such key. |
| 156 |
* |
| 157 |
* @param key the key. |
| 158 |
* @return the least key greater than the given key, or |
| 159 |
* <tt>null</tt> if there is no such key. |
| 160 |
* @throws ClassCastException if key cannot be compared with the keys |
| 161 |
* currently in the map. |
| 162 |
* @throws NullPointerException if key is <tt>null</tt> and this map |
| 163 |
* does not support <tt>null</tt> keys. |
| 164 |
*/ |
| 165 |
public K higherKey(K key); |
| 166 |
|
| 167 |
/** |
| 168 |
* Returns a key-value mapping associated with the least |
| 169 |
* key in this map, or <tt>null</tt> if the map is empty. |
| 170 |
* |
| 171 |
* @return an Entry with least key, or <tt>null</tt> |
| 172 |
* if the map is empty. |
| 173 |
*/ |
| 174 |
public Map.Entry<K,V> firstEntry(); |
| 175 |
|
| 176 |
/** |
| 177 |
* Returns a key-value mapping associated with the greatest |
| 178 |
* key in this map, or <tt>null</tt> if the map is empty. |
| 179 |
* |
| 180 |
* @return an Entry with greatest key, or <tt>null</tt> |
| 181 |
* if the map is empty. |
| 182 |
*/ |
| 183 |
public Map.Entry<K,V> lastEntry(); |
| 184 |
|
| 185 |
/** |
| 186 |
* Removes and returns a key-value mapping associated with |
| 187 |
* the least key in this map, or <tt>null</tt> if the map is empty. |
| 188 |
* |
| 189 |
* @return the removed first entry of this map, or <tt>null</tt> |
| 190 |
* if the map is empty. |
| 191 |
*/ |
| 192 |
public Map.Entry<K,V> pollFirstEntry(); |
| 193 |
|
| 194 |
/** |
| 195 |
* Removes and returns a key-value mapping associated with |
| 196 |
* the greatest key in this map, or <tt>null</tt> if the map is empty. |
| 197 |
* |
| 198 |
* @return the removed last entry of this map, or <tt>null</tt> |
| 199 |
* if the map is empty. |
| 200 |
*/ |
| 201 |
public Map.Entry<K,V> pollLastEntry(); |
| 202 |
|
| 203 |
/** |
| 204 |
* Returns a set view of the keys contained in this map, in |
| 205 |
* descending key order. The set is backed by the map, so changes |
| 206 |
* to the map are reflected in the set, and vice-versa. If the |
| 207 |
* map is modified while an iteration over the set is in progress |
| 208 |
* (except through the iterator's own <tt>remove</tt> operation), |
| 209 |
* the results of the iteration are undefined. The set supports |
| 210 |
* element removal, which removes the corresponding mapping from |
| 211 |
* the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| 212 |
* <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt> |
| 213 |
* operations. It does not support the add or <tt>addAll</tt> |
| 214 |
* operations. |
| 215 |
* |
| 216 |
* @return a set view of the keys contained in this map. |
| 217 |
*/ |
| 218 |
Set<K> descendingKeySet(); |
| 219 |
|
| 220 |
/** |
| 221 |
* Returns a set view of the mappings contained in this map, in |
| 222 |
* descending key order. Each element in the returned set is a |
| 223 |
* {@link Map.Entry}. The set is backed by the map, so changes to |
| 224 |
* the map are reflected in the set, and vice-versa. If the map |
| 225 |
* is modified while an iteration over the set is in progress |
| 226 |
* (except through the iterator's own <tt>remove</tt> operation, |
| 227 |
* or through the <tt>setValue</tt> operation on a map entry |
| 228 |
* returned by the iterator) the results of the iteration are |
| 229 |
* undefined. The set supports element removal, which removes the |
| 230 |
* corresponding mapping from the map, via the |
| 231 |
* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| 232 |
* <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt> |
| 233 |
* operations. It does not support the <tt>add</tt> or |
| 234 |
* <tt>addAll</tt> operations. |
| 235 |
* |
| 236 |
* @return a set view of the mappings contained in this map. |
| 237 |
*/ |
| 238 |
Set<Map.Entry<K, V>> descendingEntrySet(); |
| 239 |
|
| 240 |
/** |
| 241 |
* Returns a view of the portion of this map whose keys range from |
| 242 |
* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If |
| 243 |
* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned sorted map |
| 244 |
* is empty.) The returned sorted map is backed by this map, so changes |
| 245 |
* in the returned sorted map are reflected in this map, and vice-versa. |
| 246 |
|
| 247 |
* @param fromKey low endpoint (inclusive) of the subMap. |
| 248 |
* @param toKey high endpoint (exclusive) of the subMap. |
| 249 |
* |
| 250 |
* @return a view of the portion of this map whose keys range from |
| 251 |
* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. |
| 252 |
* |
| 253 |
* @throws ClassCastException if <tt>fromKey</tt> and |
| 254 |
* <tt>toKey</tt> cannot be compared to one another using this |
| 255 |
* map's comparator (or, if the map has no comparator, using |
| 256 |
* natural ordering). |
| 257 |
* @throws IllegalArgumentException if <tt>fromKey</tt> is greater |
| 258 |
* than <tt>toKey</tt>. |
| 259 |
* @throws NullPointerException if <tt>fromKey</tt> or |
| 260 |
* <tt>toKey</tt> is <tt>null</tt> and this map does not support |
| 261 |
* <tt>null</tt> keys. |
| 262 |
*/ |
| 263 |
public NavigableMap<K,V> subMap(K fromKey, K toKey); |
| 264 |
|
| 265 |
/** |
| 266 |
* Returns a view of the portion of this map whose keys are strictly less |
| 267 |
* than <tt>toKey</tt>. The returned sorted map is backed by this map, so |
| 268 |
* changes in the returned sorted map are reflected in this map, and |
| 269 |
* vice-versa. |
| 270 |
* @param toKey high endpoint (exclusive) of the headMap. |
| 271 |
* @return a view of the portion of this map whose keys are strictly |
| 272 |
* less than <tt>toKey</tt>. |
| 273 |
* |
| 274 |
* @throws ClassCastException if <tt>toKey</tt> is not compatible |
| 275 |
* with this map's comparator (or, if the map has no comparator, |
| 276 |
* if <tt>toKey</tt> does not implement <tt>Comparable</tt>). |
| 277 |
* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt> |
| 278 |
* and this map does not support <tt>null</tt> keys. |
| 279 |
*/ |
| 280 |
public NavigableMap<K,V> headMap(K toKey); |
| 281 |
|
| 282 |
/** |
| 283 |
* Returns a view of the portion of this map whose keys are |
| 284 |
* greater than or equal to <tt>fromKey</tt>. The returned sorted |
| 285 |
* map is backed by this map, so changes in the returned sorted |
| 286 |
* map are reflected in this map, and vice-versa. |
| 287 |
* @param fromKey low endpoint (inclusive) of the tailMap. |
| 288 |
* @return a view of the portion of this map whose keys are greater |
| 289 |
* than or equal to <tt>fromKey</tt>. |
| 290 |
* @throws ClassCastException if <tt>fromKey</tt> is not compatible |
| 291 |
* with this map's comparator (or, if the map has no comparator, |
| 292 |
* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>). |
| 293 |
* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt> |
| 294 |
* and this map does not support <tt>null</tt> keys. |
| 295 |
*/ |
| 296 |
public NavigableMap<K,V> tailMap(K fromKey); |
| 297 |
} |
