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Android APIs
public interface

NavigableMap

implements SortedMap<K, V>
java.util.NavigableMap<K, V>
Known Indirect Subclasses

Class Overview

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

A NavigableMap may be accessed and traversed in either ascending or descending key order. The 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 subMap, headMap, and tailMap differ from the like-named SortedMap methods in accepting additional arguments describing whether lower and upper bounds are inclusive versus exclusive. Submaps of any NavigableMap must implement the NavigableMap interface.

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

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

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

Summary

Public Methods
abstract 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 null if there is no such key.
abstract K ceilingKey(K key)
Returns the least key greater than or equal to the given key, or null if there is no such key.
abstract NavigableSet<K> descendingKeySet()
Returns a reverse order NavigableSet view of the keys contained in this map.
abstract NavigableMap<K, V> descendingMap()
Returns a reverse order view of the mappings contained in this map.
abstract Entry<K, V> firstEntry()
Returns a key-value mapping associated with the least key in this map, or null if the map is empty.
abstract 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 null if there is no such key.
abstract K floorKey(K key)
Returns the greatest key less than or equal to the given key, or null if there is no such key.
abstract 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 inclusive is true) toKey.
abstract SortedMap<K, V> headMap(K toKey)
Returns a sorted map over a range of this sorted map with all keys that are less than the specified endKey.

Equivalent to headMap(toKey, false).

abstract Entry<K, V> higherEntry(K key)
Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.
abstract K higherKey(K key)
Returns the least key strictly greater than the given key, or null if there is no such key.
abstract Entry<K, V> lastEntry()
Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
abstract Entry<K, V> lowerEntry(K key)
Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.
abstract K lowerKey(K key)
Returns the greatest key strictly less than the given key, or null if there is no such key.
abstract NavigableSet<K> navigableKeySet()
Returns a NavigableSet view of the keys contained in this map.
abstract Entry<K, V> pollFirstEntry()
Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.
abstract Entry<K, V> pollLastEntry()
Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
abstract SortedMap<K, V> subMap(K fromKey, K toKey)
Returns a sorted map over a range of this sorted map with all keys greater than or equal to the specified startKey and less than the specified endKey.

Equivalent to subMap(fromKey, true, toKey, false).

abstract 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 fromKey to toKey.
abstract SortedMap<K, V> tailMap(K fromKey)
Returns a sorted map over a range of this sorted map with all keys that are greater than or equal to the specified startKey.

Equivalent to tailMap(fromKey, true).

abstract 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 inclusive is true) fromKey.
[Expand]
Inherited Methods
From interface java.util.Map
From interface java.util.SortedMap

Public Methods

public abstract Entry<K, V> ceilingEntry (K key)

Since: API Level 9

Returns a key-value mapping associated with the least key greater than or equal to the given key, or null if there is no such key.

Parameters
key the key
Returns
  • an entry with the least key greater than or equal to key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract K ceilingKey (K key)

Since: API Level 9

Returns the least key greater than or equal to the given key, or null if there is no such key.

Parameters
key the key
Returns
  • the least key greater than or equal to key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract NavigableSet<K> descendingKeySet ()

Since: API Level 9

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 remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Returns
  • a reverse order navigable set view of the keys in this map

public abstract NavigableMap<K, V> descendingMap ()

Since: API Level 9

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 remove operation), the results of the iteration are undefined.

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

Returns
  • a reverse order view of this map

public abstract Entry<K, V> firstEntry ()

Since: API Level 9

Returns a key-value mapping associated with the least key in this map, or null if the map is empty.

Returns
  • an entry with the least key, or null if this map is empty

public abstract Entry<K, V> floorEntry (K key)

Since: API Level 9

Returns a key-value mapping associated with the greatest key less than or equal to the given key, or null if there is no such key.

Parameters
key the key
Returns
  • an entry with the greatest key less than or equal to key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract K floorKey (K key)

Since: API Level 9

Returns the greatest key less than or equal to the given key, or null if there is no such key.

Parameters
key the key
Returns
  • the greatest key less than or equal to key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract NavigableMap<K, V> headMap (K toKey, boolean inclusive)

Since: API Level 9

Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) 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 IllegalArgumentException on an attempt to insert a key outside its range.

Parameters
toKey high endpoint of the keys in the returned map
inclusive true if the high endpoint is to be included in the returned view
Returns
  • a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) toKey
Throws
ClassCastException if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
NullPointerException if toKey is null and this map does not permit null keys
IllegalArgumentException if this map itself has a restricted range, and toKey lies outside the bounds of the range

public abstract SortedMap<K, V> headMap (K toKey)

Since: API Level 11

Returns a sorted map over a range of this sorted map with all keys that are less than the specified endKey. Changes to the returned sorted map are reflected in this sorted map and vice versa.

Note: The returned map will not allow an insertion of a key outside the specified range.

Equivalent to headMap(toKey, false).

Parameters
toKey the high boundary of the range specified.
Returns
  • a sorted map where the keys are less than endKey.
Throws
ClassCastException
NullPointerException
IllegalArgumentException

public abstract Entry<K, V> higherEntry (K key)

Since: API Level 9

Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.

Parameters
key the key
Returns
  • an entry with the least key greater than key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract K higherKey (K key)

Since: API Level 9

Returns the least key strictly greater than the given key, or null if there is no such key.

Parameters
key the key
Returns
  • the least key greater than key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract Entry<K, V> lastEntry ()

Since: API Level 9

Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.

Returns
  • an entry with the greatest key, or null if this map is empty

public abstract Entry<K, V> lowerEntry (K key)

Since: API Level 9

Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.

Parameters
key the key
Returns
  • an entry with the greatest key less than key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract K lowerKey (K key)

Since: API Level 9

Returns the greatest key strictly less than the given key, or null if there is no such key.

Parameters
key the key
Returns
  • the greatest key less than key, or null if there is no such key
Throws
ClassCastException if the specified key cannot be compared with the keys currently in the map
NullPointerException if the specified key is null and this map does not permit null keys

public abstract NavigableSet<K> navigableKeySet ()

Since: API Level 9

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 remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Returns
  • a navigable set view of the keys in this map

public abstract Entry<K, V> pollFirstEntry ()

Since: API Level 9

Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.

Returns
  • the removed first entry of this map, or null if this map is empty

public abstract Entry<K, V> pollLastEntry ()

Since: API Level 9

Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.

Returns
  • the removed last entry of this map, or null if this map is empty

public abstract SortedMap<K, V> subMap (K fromKey, K toKey)

Since: API Level 11

Returns a sorted map over a range of this sorted map with all keys greater than or equal to the specified startKey and less than the specified endKey. Changes to the returned sorted map are reflected in this sorted map and vice versa.

Note: The returned map will not allow an insertion of a key outside the specified range.

Equivalent to subMap(fromKey, true, toKey, false).

Parameters
fromKey the low boundary of the range (inclusive).
toKey the high boundary of the range (exclusive),
Returns
  • a sorted map with the key from the specified range.
Throws
ClassCastException
NullPointerException
IllegalArgumentException

public abstract NavigableMap<K, V> subMap (K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)

Since: API Level 9

Returns a view of the portion of this map whose keys range from fromKey to toKey. If fromKey and toKey are equal, the returned map is empty unless fromExclusive and toExclusive 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 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.

Parameters
fromKey low endpoint of the keys in the returned map
fromInclusive true if the low endpoint is to be included in the returned view
toKey high endpoint of the keys in the returned map
toInclusive true if the high endpoint is to be included in the returned view
Returns
  • a view of the portion of this map whose keys range from fromKey to toKey
Throws
ClassCastException if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.
NullPointerException if fromKey or toKey is null and this map does not permit null keys
IllegalArgumentException if fromKey is greater than toKey; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range

public abstract SortedMap<K, V> tailMap (K fromKey)

Since: API Level 11

Returns a sorted map over a range of this sorted map with all keys that are greater than or equal to the specified startKey. Changes to the returned sorted map are reflected in this sorted map and vice versa.

Note: The returned map will not allow an insertion of a key outside the specified range.

Equivalent to tailMap(fromKey, true).

Parameters
fromKey the low boundary of the range specified.
Returns
  • a sorted map where the keys are greater or equal to startKey.
Throws
ClassCastException
NullPointerException
IllegalArgumentException

public abstract NavigableMap<K, V> tailMap (K fromKey, boolean inclusive)

Since: API Level 9

Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) 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 IllegalArgumentException on an attempt to insert a key outside its range.

Parameters
fromKey low endpoint of the keys in the returned map
inclusive true if the low endpoint is to be included in the returned view
Returns
  • a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) fromKey
Throws
ClassCastException if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
NullPointerException if fromKey is null and this map does not permit null keys
IllegalArgumentException if this map itself has a restricted range, and fromKey lies outside the bounds of the range