Home » openjdk-7 » java » util » [javadoc | source]
java.util
public interface: NavigableMap [javadoc | source]

All Implemented Interfaces:
    SortedMap

All Known Implementing Classes:
    TreeMap, ConcurrentNavigableMap, SubMap, DescendingSubMap, ConcurrentSkipListMap, AscendingSubMap, NavigableSubMap

A SortedMap extended with navigation methods returning the closest matches for given search targets. Methods {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry}, and {@code higherEntry} return {@code Map.Entry} objects associated with keys respectively less than, less than or equal, greater than or equal, and greater than a given key, returning {@code null} if there is no such key. Similarly, methods {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and {@code higherKey} return only the associated keys. All of these methods are designed for locating, not traversing entries.

A {@code NavigableMap} may be accessed and traversed in either ascending or descending key order. The {@code descendingMap} method returns a view of the map with the senses of all relational and directional methods inverted. The performance of ascending operations and views is likely to be faster than that of descending ones. Methods {@code subMap}, {@code headMap}, and {@code tailMap} differ from the like-named {@code SortedMap} methods in accepting additional arguments describing whether lower and upper bounds are inclusive versus exclusive. Submaps of any {@code NavigableMap} must implement the {@code NavigableMap} interface.

This interface additionally defines methods {@code firstEntry}, {@code pollFirstEntry}, {@code lastEntry}, and {@code pollLastEntry} that return and/or remove the least and greatest mappings, if any exist, else returning {@code null}.

Implementations of entry-returning methods are expected to return {@code Map.Entry} pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional {@code Entry.setValue} method. Note however that it is possible to change mappings in the associated map using method {@code put}.

Methods subMap(K, K) , headMap(K) , and tailMap(K) are specified to return {@code SortedMap} to allow existing implementations of {@code SortedMap} to be compatibly retrofitted to implement {@code NavigableMap}, but extensions and implementations of this interface are encouraged to override these methods to return {@code NavigableMap}. Similarly, #keySet() can be overriden to return {@code NavigableSet}.

This interface is a member of the Java Collections Framework.

Method from java.util.NavigableMap Summary:
ceilingEntry,   ceilingKey,   descendingKeySet,   descendingMap,   firstEntry,   floorEntry,   floorKey,   headMap,   headMap,   higherEntry,   higherKey,   lastEntry,   lowerEntry,   lowerKey,   navigableKeySet,   pollFirstEntry,   pollLastEntry,   subMap,   subMap,   tailMap,   tailMap
Method from java.util.NavigableMap Detail:
 public Entry<K, V> ceilingEntry(K key)
    Returns a key-value mapping associated with the least key greater than or equal to the given key, or {@code null} if there is no such key.
 public K ceilingKey(K key)
    Returns the least key greater than or equal to the given key, or {@code null} if there is no such key.
 public NavigableSet<K> descendingKeySet()
    Returns a reverse order NavigableSet view of the keys contained in this map. The set's iterator returns the keys in descending order. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own {@code remove} operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the {@code Iterator.remove}, {@code Set.remove}, {@code removeAll}, {@code retainAll}, and {@code clear} operations. It does not support the {@code add} or {@code addAll} operations.
 public NavigableMap<K, V> descendingMap()
    Returns a reverse order view of the mappings contained in this map. The descending map is backed by this map, so changes to the map are reflected in the descending map, and vice-versa. If either map is modified while an iteration over a collection view of either map is in progress (except through the iterator's own {@code remove} operation), the results of the iteration are undefined.

    The returned map has an ordering equivalent to Collections.reverseOrder (comparator()). The expression {@code m.descendingMap().descendingMap()} returns a view of {@code m} essentially equivalent to {@code m}.

 public Entry<K, V> firstEntry()
    Returns a key-value mapping associated with the least key in this map, or {@code null} if the map is empty.
 public Entry<K, V> floorEntry(K key)
    Returns a key-value mapping associated with the greatest key less than or equal to the given key, or {@code null} if there is no such key.
 public K floorKey(K key)
    Returns the greatest key less than or equal to the given key, or {@code null} if there is no such key.
 public SortedMap<K, V> headMap(K toKey)
    {@inheritDoc}

    Equivalent to {@code headMap(toKey, false)}.

 public NavigableMap<K, V> headMap(K toKey,
    boolean inclusive)
    Returns a view of the portion of this map whose keys are less than (or equal to, if {@code inclusive} is true) {@code toKey}. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

    The returned map will throw an {@code IllegalArgumentException} on an attempt to insert a key outside its range.

 public Entry<K, V> higherEntry(K key)
    Returns a key-value mapping associated with the least key strictly greater than the given key, or {@code null} if there is no such key.
 public K higherKey(K key)
    Returns the least key strictly greater than the given key, or {@code null} if there is no such key.
 public Entry<K, V> lastEntry()
    Returns a key-value mapping associated with the greatest key in this map, or {@code null} if the map is empty.
 public Entry<K, V> lowerEntry(K key)
    Returns a key-value mapping associated with the greatest key strictly less than the given key, or {@code null} if there is no such key.
 public K lowerKey(K key)
    Returns the greatest key strictly less than the given key, or {@code null} if there is no such key.
 public NavigableSet<K> navigableKeySet()
    Returns a NavigableSet view of the keys contained in this map. The set's iterator returns the keys in ascending order. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own {@code remove} operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the {@code Iterator.remove}, {@code Set.remove}, {@code removeAll}, {@code retainAll}, and {@code clear} operations. It does not support the {@code add} or {@code addAll} operations.
 public Entry<K, V> pollFirstEntry()
    Removes and returns a key-value mapping associated with the least key in this map, or {@code null} if the map is empty.
 public Entry<K, V> pollLastEntry()
    Removes and returns a key-value mapping associated with the greatest key in this map, or {@code null} if the map is empty.
 public SortedMap<K, V> subMap(K fromKey,
    K toKey)
    {@inheritDoc}

    Equivalent to {@code subMap(fromKey, true, toKey, false)}.

 public NavigableMap<K, V> subMap(K fromKey,
    boolean fromInclusive,
    K toKey,
    boolean toInclusive)
    Returns a view of the portion of this map whose keys range from {@code fromKey} to {@code toKey}. If {@code fromKey} and {@code toKey} are equal, the returned map is empty unless {@code fromInclusive} and {@code toInclusive} are both true. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

    The returned map will throw an {@code IllegalArgumentException} on an attempt to insert a key outside of its range, or to construct a submap either of whose endpoints lie outside its range.

 public SortedMap<K, V> tailMap(K fromKey)
    {@inheritDoc}

    Equivalent to {@code tailMap(fromKey, true)}.

 public NavigableMap<K, V> tailMap(K fromKey,
    boolean inclusive)
    Returns a view of the portion of this map whose keys are greater than (or equal to, if {@code inclusive} is true) {@code fromKey}. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.

    The returned map will throw an {@code IllegalArgumentException} on an attempt to insert a key outside its range.