Source for java.util.NavigableMap

   1: /*
   2:  * Written by Doug Lea and Josh Bloch with assistance from members of JCP
   3:  * JSR-166 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 SortedMap} extended with navigation methods returning the
  11:  * closest matches for given search targets. Methods
  12:  * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
  13:  * and {@code higherEntry} return {@code Map.Entry} objects
  14:  * associated with keys respectively less than, less than or equal,
  15:  * greater than or equal, and greater than a given key, returning
  16:  * {@code null} if there is no such key.  Similarly, methods
  17:  * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
  18:  * {@code higherKey} return only the associated keys. All of these
  19:  * methods are designed for locating, not traversing entries.
  20:  *
  21:  * <p>A {@code NavigableMap} may be accessed and traversed in either
  22:  * ascending or descending key order.  The {@code descendingMap}
  23:  * method returns a view of the map with the senses of all relational
  24:  * and directional methods inverted. The performance of ascending
  25:  * operations and views is likely to be faster than that of descending
  26:  * ones.  Methods {@code subMap}, {@code headMap},
  27:  * and {@code tailMap} differ from the like-named {@code
  28:  * SortedMap} methods in accepting additional arguments describing
  29:  * whether lower and upper bounds are inclusive versus exclusive.
  30:  * Submaps of any {@code NavigableMap} must implement the {@code
  31:  * NavigableMap} interface.
  32:  *
  33:  * <p>This interface additionally defines methods {@code firstEntry},
  34:  * {@code pollFirstEntry}, {@code lastEntry}, and
  35:  * {@code pollLastEntry} that return and/or remove the least and
  36:  * greatest mappings, if any exist, else returning {@code null}.
  37:  *
  38:  * <p>Implementations of entry-returning methods are expected to
  39:  * return {@code Map.Entry} pairs representing snapshots of mappings
  40:  * at the time they were produced, and thus generally do <em>not</em>
  41:  * support the optional {@code Entry.setValue} method. Note however
  42:  * that it is possible to change mappings in the associated map using
  43:  * method {@code put}.
  44:  *
  45:  * <p>Methods
  46:  * {@link #subMap(Object, Object) subMap(K, K)},
  47:  * {@link #headMap(Object) headMap(K)}, and
  48:  * {@link #tailMap(Object) tailMap(K)}
  49:  * are specified to return {@code SortedMap} to allow existing
  50:  * implementations of {@code SortedMap} to be compatibly retrofitted to
  51:  * implement {@code NavigableMap}, but extensions and implementations
  52:  * of this interface are encouraged to override these methods to return
  53:  * {@code NavigableMap}.  Similarly,
  54:  * {@link #keySet()} can be overriden to return {@code NavigableSet}.
  55:  *
  56:  * <p>This interface is a member of the
  57:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
  58:  * Java Collections Framework</a>.
  59:  *
  60:  * @author Doug Lea
  61:  * @author Josh Bloch
  62:  * @param <K> the type of keys maintained by this map
  63:  * @param <V> the type of mapped values
  64:  * @since 1.6
  65:  */
  66: public interface NavigableMap<K,V> extends SortedMap<K,V> {
  67:     /**
  68:      * Returns a key-value mapping associated with the greatest key
  69:      * strictly less than the given key, or {@code null} if there is
  70:      * no such key.
  71:      *
  72:      * @param key the key
  73:      * @return an entry with the greatest key less than {@code key},
  74:      *         or {@code null} if there is no such key
  75:      * @throws ClassCastException if the specified key cannot be compared
  76:      *         with the keys currently in the map
  77:      * @throws NullPointerException if the specified key is null
  78:      *         and this map does not permit null keys
  79:      */
  80:     Map.Entry<K,V> lowerEntry(K key);
  81: 
  82:     /**
  83:      * Returns the greatest key strictly less than the given key, or
  84:      * {@code null} if there is no such key.
  85:      *
  86:      * @param key the key
  87:      * @return the greatest key less than {@code key},
  88:      *         or {@code null} if there is no such key
  89:      * @throws ClassCastException if the specified key cannot be compared
  90:      *         with the keys currently in the map
  91:      * @throws NullPointerException if the specified key is null
  92:      *         and this map does not permit null keys
  93:      */
  94:     K lowerKey(K key);
  95: 
  96:     /**
  97:      * Returns a key-value mapping associated with the greatest key
  98:      * less than or equal to the given key, or {@code null} if there
  99:      * is no such key.
 100:      *
 101:      * @param key the key
 102:      * @return an entry with the greatest key less than or equal to
 103:      *         {@code key}, or {@code null} if there is no such key
 104:      * @throws ClassCastException if the specified key cannot be compared
 105:      *         with the keys currently in the map
 106:      * @throws NullPointerException if the specified key is null
 107:      *         and this map does not permit null keys
 108:      */
 109:     Map.Entry<K,V> floorEntry(K key);
 110: 
 111:     /**
 112:      * Returns the greatest key less than or equal to the given key,
 113:      * or {@code null} if there is no such key.
 114:      *
 115:      * @param key the key
 116:      * @return the greatest key less than or equal to {@code key},
 117:      *         or {@code null} if there is no such key
 118:      * @throws ClassCastException if the specified key cannot be compared
 119:      *         with the keys currently in the map
 120:      * @throws NullPointerException if the specified key is null
 121:      *         and this map does not permit null keys
 122:      */
 123:     K floorKey(K key);
 124: 
 125:     /**
 126:      * Returns a key-value mapping associated with the least key
 127:      * greater than or equal to the given key, or {@code null} if
 128:      * there is no such key.
 129:      *
 130:      * @param key the key
 131:      * @return an entry with the least key greater than or equal to
 132:      *         {@code key}, or {@code null} if there is no such key
 133:      * @throws ClassCastException if the specified key cannot be compared
 134:      *         with the keys currently in the map
 135:      * @throws NullPointerException if the specified key is null
 136:      *         and this map does not permit null keys
 137:      */
 138:     Map.Entry<K,V> ceilingEntry(K key);
 139: 
 140:     /**
 141:      * Returns the least key greater than or equal to the given key,
 142:      * or {@code null} if there is no such key.
 143:      *
 144:      * @param key the key
 145:      * @return the least key greater than or equal to {@code key},
 146:      *         or {@code null} if there is no such key
 147:      * @throws ClassCastException if the specified key cannot be compared
 148:      *         with the keys currently in the map
 149:      * @throws NullPointerException if the specified key is null
 150:      *         and this map does not permit null keys
 151:      */
 152:     K ceilingKey(K key);
 153: 
 154:     /**
 155:      * Returns a key-value mapping associated with the least key
 156:      * strictly greater than the given key, or {@code null} if there
 157:      * is no such key.
 158:      *
 159:      * @param key the key
 160:      * @return an entry with the least key greater than {@code key},
 161:      *         or {@code null} if there is no such key
 162:      * @throws ClassCastException if the specified key cannot be compared
 163:      *         with the keys currently in the map
 164:      * @throws NullPointerException if the specified key is null
 165:      *         and this map does not permit null keys
 166:      */
 167:     Map.Entry<K,V> higherEntry(K key);
 168: 
 169:     /**
 170:      * Returns the least key strictly greater than the given key, or
 171:      * {@code null} if there is no such key.
 172:      *
 173:      * @param key the key
 174:      * @return the least key greater than {@code key},
 175:      *         or {@code null} if there is no such key
 176:      * @throws ClassCastException if the specified key cannot be compared
 177:      *         with the keys currently in the map
 178:      * @throws NullPointerException if the specified key is null
 179:      *         and this map does not permit null keys
 180:      */
 181:     K higherKey(K key);
 182: 
 183:     /**
 184:      * Returns a key-value mapping associated with the least
 185:      * key in this map, or {@code null} if the map is empty.
 186:      *
 187:      * @return an entry with the least key,
 188:      *         or {@code null} if this map is empty
 189:      */
 190:     Map.Entry<K,V> firstEntry();
 191: 
 192:     /**
 193:      * Returns a key-value mapping associated with the greatest
 194:      * key in this map, or {@code null} if the map is empty.
 195:      *
 196:      * @return an entry with the greatest key,
 197:      *         or {@code null} if this map is empty
 198:      */
 199:     Map.Entry<K,V> lastEntry();
 200: 
 201:     /**
 202:      * Removes and returns a key-value mapping associated with
 203:      * the least key in this map, or {@code null} if the map is empty.
 204:      *
 205:      * @return the removed first entry of this map,
 206:      *         or {@code null} if this map is empty
 207:      */
 208:     Map.Entry<K,V> pollFirstEntry();
 209: 
 210:     /**
 211:      * Removes and returns a key-value mapping associated with
 212:      * the greatest key in this map, or {@code null} if the map is empty.
 213:      *
 214:      * @return the removed last entry of this map,
 215:      *         or {@code null} if this map is empty
 216:      */
 217:     Map.Entry<K,V> pollLastEntry();
 218: 
 219:     /**
 220:      * Returns a reverse order view of the mappings contained in this map.
 221:      * The descending map is backed by this map, so changes to the map are
 222:      * reflected in the descending map, and vice-versa.  If either map is
 223:      * modified while an iteration over a collection view of either map
 224:      * is in progress (except through the iterator's own {@code remove}
 225:      * operation), the results of the iteration are undefined.
 226:      *
 227:      * <p>The returned map has an ordering equivalent to
 228:      * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
 229:      * The expression {@code m.descendingMap().descendingMap()} returns a
 230:      * view of {@code m} essentially equivalent to {@code m}.
 231:      *
 232:      * @return a reverse order view of this map
 233:      */
 234:     NavigableMap<K,V> descendingMap();
 235: 
 236:     /**
 237:      * Returns a {@link NavigableSet} view of the keys contained in this map.
 238:      * The set's iterator returns the keys in ascending order.
 239:      * The set is backed by the map, so changes to the map are reflected in
 240:      * the set, and vice-versa.  If the map is modified while an iteration
 241:      * over the set is in progress (except through the iterator's own {@code
 242:      * remove} operation), the results of the iteration are undefined.  The
 243:      * set supports element removal, which removes the corresponding mapping
 244:      * from the map, via the {@code Iterator.remove}, {@code Set.remove},
 245:      * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
 246:      * It does not support the {@code add} or {@code addAll} operations.
 247:      *
 248:      * @return a navigable set view of the keys in this map
 249:      */
 250:     NavigableSet<K> navigableKeySet();
 251: 
 252:     /**
 253:      * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.
 254:      * The set's iterator returns the keys in descending order.
 255:      * The set is backed by the map, so changes to the map are reflected in
 256:      * the set, and vice-versa.  If the map is modified while an iteration
 257:      * over the set is in progress (except through the iterator's own {@code
 258:      * remove} operation), the results of the iteration are undefined.  The
 259:      * set supports element removal, which removes the corresponding mapping
 260:      * from the map, via the {@code Iterator.remove}, {@code Set.remove},
 261:      * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
 262:      * It does not support the {@code add} or {@code addAll} operations.
 263:      *
 264:      * @return a reverse order navigable set view of the keys in this map
 265:      */
 266:     NavigableSet<K> descendingKeySet();
 267: 
 268:     /**
 269:      * Returns a view of the portion of this map whose keys range from
 270:      * {@code fromKey} to {@code toKey}.  If {@code fromKey} and
 271:      * {@code toKey} are equal, the returned map is empty unless
 272:      * {@code fromExclusive} and {@code toExclusive} are both true.  The
 273:      * returned map is backed by this map, so changes in the returned map are
 274:      * reflected in this map, and vice-versa.  The returned map supports all
 275:      * optional map operations that this map supports.
 276:      *
 277:      * <p>The returned map will throw an {@code IllegalArgumentException}
 278:      * on an attempt to insert a key outside of its range, or to construct a
 279:      * submap either of whose endpoints lie outside its range.
 280:      *
 281:      * @param fromKey low endpoint of the keys in the returned map
 282:      * @param fromInclusive {@code true} if the low endpoint
 283:      *        is to be included in the returned view
 284:      * @param toKey high endpoint of the keys in the returned map
 285:      * @param toInclusive {@code true} if the high endpoint
 286:      *        is to be included in the returned view
 287:      * @return a view of the portion of this map whose keys range from
 288:      *         {@code fromKey} to {@code toKey}
 289:      * @throws ClassCastException if {@code fromKey} and {@code toKey}
 290:      *         cannot be compared to one another using this map's comparator
 291:      *         (or, if the map has no comparator, using natural ordering).
 292:      *         Implementations may, but are not required to, throw this
 293:      *         exception if {@code fromKey} or {@code toKey}
 294:      *         cannot be compared to keys currently in the map.
 295:      * @throws NullPointerException if {@code fromKey} or {@code toKey}
 296:      *         is null and this map does not permit null keys
 297:      * @throws IllegalArgumentException if {@code fromKey} is greater than
 298:      *         {@code toKey}; or if this map itself has a restricted
 299:      *         range, and {@code fromKey} or {@code toKey} lies
 300:      *         outside the bounds of the range
 301:      */
 302:     NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,
 303:                              K toKey,   boolean toInclusive);
 304: 
 305:     /**
 306:      * Returns a view of the portion of this map whose keys are less than (or
 307:      * equal to, if {@code inclusive} is true) {@code toKey}.  The returned
 308:      * map is backed by this map, so changes in the returned map are reflected
 309:      * in this map, and vice-versa.  The returned map supports all optional
 310:      * map operations that this map supports.
 311:      *
 312:      * <p>The returned map will throw an {@code IllegalArgumentException}
 313:      * on an attempt to insert a key outside its range.
 314:      *
 315:      * @param toKey high endpoint of the keys in the returned map
 316:      * @param inclusive {@code true} if the high endpoint
 317:      *        is to be included in the returned view
 318:      * @return a view of the portion of this map whose keys are less than
 319:      *         (or equal to, if {@code inclusive} is true) {@code toKey}
 320:      * @throws ClassCastException if {@code toKey} is not compatible
 321:      *         with this map's comparator (or, if the map has no comparator,
 322:      *         if {@code toKey} does not implement {@link Comparable}).
 323:      *         Implementations may, but are not required to, throw this
 324:      *         exception if {@code toKey} cannot be compared to keys
 325:      *         currently in the map.
 326:      * @throws NullPointerException if {@code toKey} is null
 327:      *         and this map does not permit null keys
 328:      * @throws IllegalArgumentException if this map itself has a
 329:      *         restricted range, and {@code toKey} lies outside the
 330:      *         bounds of the range
 331:      */
 332:     NavigableMap<K,V> headMap(K toKey, boolean inclusive);
 333: 
 334:     /**
 335:      * Returns a view of the portion of this map whose keys are greater than (or
 336:      * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned
 337:      * map is backed by this map, so changes in the returned map are reflected
 338:      * in this map, and vice-versa.  The returned map supports all optional
 339:      * map operations that this map supports.
 340:      *
 341:      * <p>The returned map will throw an {@code IllegalArgumentException}
 342:      * on an attempt to insert a key outside its range.
 343:      *
 344:      * @param fromKey low endpoint of the keys in the returned map
 345:      * @param inclusive {@code true} if the low endpoint
 346:      *        is to be included in the returned view
 347:      * @return a view of the portion of this map whose keys are greater than
 348:      *         (or equal to, if {@code inclusive} is true) {@code fromKey}
 349:      * @throws ClassCastException if {@code fromKey} is not compatible
 350:      *         with this map's comparator (or, if the map has no comparator,
 351:      *         if {@code fromKey} does not implement {@link Comparable}).
 352:      *         Implementations may, but are not required to, throw this
 353:      *         exception if {@code fromKey} cannot be compared to keys
 354:      *         currently in the map.
 355:      * @throws NullPointerException if {@code fromKey} is null
 356:      *         and this map does not permit null keys
 357:      * @throws IllegalArgumentException if this map itself has a
 358:      *         restricted range, and {@code fromKey} lies outside the
 359:      *         bounds of the range
 360:      */
 361:     NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);
 362: 
 363:     /**
 364:      * {@inheritDoc}
 365:      *
 366:      * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.
 367:      *
 368:      * @throws ClassCastException       {@inheritDoc}
 369:      * @throws NullPointerException     {@inheritDoc}
 370:      * @throws IllegalArgumentException {@inheritDoc}
 371:      */
 372:     SortedMap<K,V> subMap(K fromKey, K toKey);
 373: 
 374:     /**
 375:      * {@inheritDoc}
 376:      *
 377:      * <p>Equivalent to {@code headMap(toKey, false)}.
 378:      *
 379:      * @throws ClassCastException       {@inheritDoc}
 380:      * @throws NullPointerException     {@inheritDoc}
 381:      * @throws IllegalArgumentException {@inheritDoc}
 382:      */
 383:     SortedMap<K,V> headMap(K toKey);
 384: 
 385:     /**
 386:      * {@inheritDoc}
 387:      *
 388:      * <p>Equivalent to {@code tailMap(fromKey, true)}.
 389:      *
 390:      * @throws ClassCastException       {@inheritDoc}
 391:      * @throws NullPointerException     {@inheritDoc}
 392:      * @throws IllegalArgumentException {@inheritDoc}
 393:      */
 394:     SortedMap<K,V> tailMap(K fromKey);
 395: }