Added in API level 9

Summary: Methods | Inherited Methods

NavigableMap

public interface NavigableMap
implements SortedMap<K, V>

java.util.NavigableMap<K, V>

Known indirect subclasses

ConcurrentNavigableMap<K, V>, ConcurrentSkipListMap<K, V>, TreeMap<K, V>

ConcurrentNavigableMap<K, V>	A `ConcurrentMap` supporting `NavigableMap` operations, and recursively so for its navigable sub-maps.
ConcurrentSkipListMap<K, V>	A scalable concurrent `ConcurrentNavigableMap` implementation.
TreeMap<K, V>	A Red-Black tree based `NavigableMap` implementation.

A SortedMap extended with navigation methods returning the closest matches for given search targets. Methods lowerEntry(K), floorEntry(K), ceilingEntry(K), and higherEntry(K) 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(K), floorKey(K), ceilingKey(K), and higherKey(K) 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(K, boolean, K, boolean), headMap(K, boolean), and tailMap(K, boolean) 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.

The methods ceilingEntry(K), firstEntry(), floorEntry(K), higherEntry(K), lastEntry(), lowerEntry(K), pollFirstEntry(), and pollLastEntry() return Map.Entry instances that represent snapshots of mappings as of the time of the call. They do not support mutation of the underlying map via the optional setValue method.

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, SortedMap.keySet() can be overridden 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 SortedMap<K, V>`	`headMap(K toKey)` Returns a view of the portion of this map whose keys are strictly less than `toKey`. Equivalent to `headMap(toKey, false)`.
`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 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.
`default NavigableMap<K, V>`	`reversed()` Returns a reverse-ordered view of this map. This method is equivalent to `descendingMap`.
`abstract SortedMap<K, V>`	`subMap(K fromKey, K toKey)` Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive. 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 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`.
`abstract SortedMap<K, V>`	`tailMap(K fromKey)` Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`. Equivalent to `tailMap(fromKey, true)`.

Inherited methods

From interface


        
          java.util.SortedMap

`abstract Comparator<? super K>`	`comparator()` Returns the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys.
`abstract Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`abstract K`	`firstKey()` Returns the first (lowest) key currently in this map.
`abstract SortedMap<K, V>`	`headMap(K toKey)` Returns a view of the portion of this map whose keys are strictly less than `toKey`.
`abstract Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`abstract K`	`lastKey()` Returns the last (highest) key currently in this map.
`default V`	`putFirst(K k, V v)` Throws `UnsupportedOperationException`.
`default V`	`putLast(K k, V v)` Throws `UnsupportedOperationException`.
`default SortedMap<K, V>`	`reversed()` Returns a reverse-ordered view of this map.
`abstract SortedMap<K, V>`	`subMap(K fromKey, K toKey)` Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive.
`abstract SortedMap<K, V>`	`tailMap(K fromKey)` Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`.
`abstract Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map.

From interface


        
          java.util.Map

`abstract void`	`clear()` Removes all of the mappings from this map (optional operation).
`default V`	`compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)` Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping).
`default V`	`computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction)` If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into this map unless `null`.
`default V`	`computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction)` If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
`abstract boolean`	`containsKey(Object key)` Returns `true` if this map contains a mapping for the specified key.
`abstract boolean`	`containsValue(Object value)` Returns `true` if this map maps one or more keys to the specified value.
`static <K, V> Map<K, V>`	`copyOf(Map<? extends K, ? extends V> map)` Returns an unmodifiable Map containing the entries of the given Map.
`static <K, V> Entry<K, V>`	`entry(K k, V v)` Returns an unmodifiable `Entry` containing the given key and value.
`abstract Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`abstract boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`default void`	`forEach(BiConsumer<? super K, ? super V> action)` Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
`abstract V`	`get(Object key)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
`default V`	`getOrDefault(Object key, V defaultValue)` Returns the value to which the specified key is mapped, or `defaultValue` if this map contains no mapping for the key.
`abstract int`	`hashCode()` Returns the hash code value for this map.
`abstract boolean`	`isEmpty()` Returns `true` if this map contains no key-value mappings.
`abstract Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`default V`	`merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction)` If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5)` Returns an unmodifiable map containing five mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4)` Returns an unmodifiable map containing four mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1)` Returns an unmodifiable map containing a single mapping.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8)` Returns an unmodifiable map containing eight mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2)` Returns an unmodifiable map containing two mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3)` Returns an unmodifiable map containing three mappings.
`static <K, V> Map<K, V>`	`of()` Returns an unmodifiable map containing zero mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9)` Returns an unmodifiable map containing nine mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6)` Returns an unmodifiable map containing six mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7)` Returns an unmodifiable map containing seven mappings.
`static <K, V> Map<K, V>`	`of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7, K k8, V v8, K k9, V v9, K k10, V v10)` Returns an unmodifiable map containing ten mappings.
`static <K, V> Map<K, V>`	`ofEntries(Entry...<? extends K, ? extends V> entries)` Returns an unmodifiable map containing keys and values extracted from the given entries.
`abstract V`	`put(K key, V value)` Associates the specified value with the specified key in this map (optional operation).
`abstract void`	`putAll(Map<? extends K, ? extends V> m)` Copies all of the mappings from the specified map to this map (optional operation).
`default V`	`putIfAbsent(K key, V value)` If the specified key is not already associated with a value (or is mapped to `null`) associates it with the given value and returns `null`, else returns the current value.
`default boolean`	`remove(Object key, Object value)` Removes the entry for the specified key only if it is currently mapped to the specified value.
`abstract V`	`remove(Object key)` Removes the mapping for a key from this map if it is present (optional operation).
`default boolean`	`replace(K key, V oldValue, V newValue)` Replaces the entry for the specified key only if currently mapped to the specified value.
`default V`	`replace(K key, V value)` Replaces the entry for the specified key only if it is currently mapped to some value.
`default void`	`replaceAll(BiFunction<? super K, ? super V, ? extends V> function)` Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
`abstract int`	`size()` Returns the number of key-value mappings in this map.
`abstract Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map.

From interface


        
          java.util.SequencedMap

`default Entry<K, V>`	`firstEntry()` Returns the first key-value mapping in this map, or `null` if the map is empty.
`default Entry<K, V>`	`lastEntry()` Returns the last key-value mapping in this map, or `null` if the map is empty.
`default Entry<K, V>`	`pollFirstEntry()` Removes and returns the first key-value mapping in this map, or `null` if the map is empty (optional operation).
`default Entry<K, V>`	`pollLastEntry()` Removes and returns the last key-value mapping in this map, or `null` if the map is empty (optional operation).
`default V`	`putFirst(K k, V v)` Inserts the given mapping into the map if it is not already present, or replaces the value of a mapping if it is already present (optional operation).
`default V`	`putLast(K k, V v)` Inserts the given mapping into the map if it is not already present, or replaces the value of a mapping if it is already present (optional operation).
`abstract SequencedMap<K, V>`	`reversed()` Returns a reverse-ordered view of this map.
`default SequencedSet<Entry<K, V>>`	`sequencedEntrySet()` Returns a `SequencedSet` view of this map's `entrySet`.
`default SequencedSet<K>`	`sequencedKeySet()` Returns a `SequencedSet` view of this map's `keySet`.
`default SequencedCollection<V>`	`sequencedValues()` Returns a `SequencedCollection` view of this map's `values` collection.

Public methods

ceilingEntry

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`Entry<K, V>`	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

ceilingKey

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`K`	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

descendingKeySet

Added in API level 9

public abstract 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 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
`NavigableSet<K>`	a reverse order navigable set view of the keys in this map

descendingMap

Added in API level 9

public abstract 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 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
`NavigableMap<K, V>`	a reverse order view of this map

firstEntry

Added in API level 9

public 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.

Returns
`Entry<K, V>`	an entry with the least key, or `null` if this map is empty

floorEntry

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`Entry<K, V>`	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

floorKey

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`K`	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

headMap

Added in API level 9

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

Returns a view of the portion of this map whose keys are strictly less than 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.

Equivalent to headMap(toKey, false).

Parameters
`toKey`	`K`: high endpoint (exclusive) of the keys in the returned map

Returns
`SortedMap<K, V>`	a view of the portion of this map whose keys are strictly less than `toKey`

Throws
`ClassCastException`
`NullPointerException`
`IllegalArgumentException`

headMap

Added in API level 9

public 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. 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`	`K`: high endpoint of the keys in the returned map
`inclusive`	`boolean`: `true` if the high endpoint is to be included in the returned view

Returns
`NavigableMap<K, V>`	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

higherEntry

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`Entry<K, V>`	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

higherKey

Added in API level 9

public abstract K higherKey (K key)

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

Parameters
`key`	`K`: the key

Returns
`K`	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

lastEntry

Added in API level 9

public 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.

Returns
`Entry<K, V>`	an entry with the greatest key, or `null` if this map is empty

lowerEntry

Added in API level 9

public 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.

Parameters
`key`	`K`: the key

Returns
`Entry<K, V>`	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

lowerKey

Added in API level 9

public abstract K lowerKey (K key)

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

Parameters
`key`	`K`: the key

Returns
`K`	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

navigableKeySet

Added in API level 9

public abstract 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 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
`NavigableSet<K>`	a navigable set view of the keys in this map

pollFirstEntry

Added in API level 9

public 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.

Returns
`Entry<K, V>`	the removed first entry of this map, or `null` if this map is empty

pollLastEntry

Added in API level 9

public 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.

Returns
`Entry<K, V>`	the removed last entry of this map, or `null` if this map is empty

reversed

Added in API level 35

public NavigableMap<K, V> reversed ()

Returns a reverse-ordered view of this map. The encounter order of mappings in the returned view is the inverse of the encounter order of mappings in this map. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the implementation permits modifications to this view, the modifications "write through" to the underlying map. Changes to the underlying map might or might not be visible in this reversed view, depending upon the implementation.

This method is equivalent to descendingMap.

Implementation Requirements:

The implementation in this interface returns the result of calling the descendingMap method.

Returns
`NavigableMap<K, V>`	a reverse-ordered view of this map, as a `NavigableMap`

subMap

Added in API level 9

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

Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. (If fromKey and toKey are equal, the returned map is empty.) 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.

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

Parameters
`fromKey`	`K`: low endpoint (inclusive) of the keys in the returned map
`toKey`	`K`: high endpoint (exclusive) of the keys in the returned map

Returns
`SortedMap<K, V>`	a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive

Throws
`ClassCastException`
`NullPointerException`
`IllegalArgumentException`

subMap

Added in API level 9

public 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. If fromKey and toKey are equal, the returned map is empty unless fromInclusive and 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 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`	`K`: low endpoint of the keys in the returned map
`fromInclusive`	`boolean`: `true` if the low endpoint is to be included in the returned view
`toKey`	`K`: high endpoint of the keys in the returned map
`toInclusive`	`boolean`: `true` if the high endpoint is to be included in the returned view

Returns
`NavigableMap<K, V>`	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

tailMap

Added in API level 9

public 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. 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`	`K`: low endpoint of the keys in the returned map
`inclusive`	`boolean`: `true` if the low endpoint is to be included in the returned view

Returns
`NavigableMap<K, V>`	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

tailMap

Added in API level 9

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

Returns a view of the portion of this map whose keys are greater than or equal to 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.

Equivalent to tailMap(fromKey, true).

Parameters
`fromKey`	`K`: low endpoint (inclusive) of the keys in the returned map

Returns
`SortedMap<K, V>`	a view of the portion of this map whose keys are greater than or equal to `fromKey`

Throws
`ClassCastException`
`NullPointerException`
`IllegalArgumentException`