edu.emory.mathcs.backport.java.util.concurrent
Class ConcurrentSkipListMap

java.lang.Object
  java.util.AbstractMap
      edu.emory.mathcs.backport.java.util.AbstractMap
          edu.emory.mathcs.backport.java.util.concurrent.ConcurrentSkipListMap

All Implemented Interfaces:

java.lang.Cloneable, ConcurrentMap, ConcurrentNavigableMap, java.util.Map, NavigableMap, java.io.Serializable, java.util.SortedMap

public class ConcurrentSkipListMap

extends AbstractMap

implements ConcurrentNavigableMap, java.lang.Cloneable, java.io.Serializable

A scalable concurrent ConcurrentNavigableMap implementation. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.

This class implements a concurrent variant of SkipLists providing expected average log(n) time cost for the containsKey, get, put and remove operations and their variants. Insertion, removal, update, and access operations safely execute concurrently by multiple threads. Iterators are weakly consistent, returning elements reflecting the state of the map at some point at or since the creation of the iterator. They do not throw ConcurrentModificationException, and may proceed concurrently with other operations. Ascending key ordered views and their iterators are faster than descending ones.

All Map.Entry pairs returned by methods in this class and its views represent snapshots of mappings at the time they were produced. They do not support the Entry.setValue method. (Note however that it is possible to change mappings in the associated map using put, putIfAbsent, or replace, depending on exactly which effect you need.)

Beware that, unlike in most collections, the size method is not a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires a traversal of the elements. Additionally, the bulk operations putAll, equals, and clear are not guaranteed to be performed atomically. For example, an iterator operating concurrently with a putAll operation might view only some of the added elements.

This class and its views and iterators implement all of the optional methods of the Map and Iterator interfaces. Like most other concurrent collections, this class does not permit the use of null keys or values because some null return values cannot be reliably distinguished from the absence of elements.

This class is a member of the Java Collections Framework.

Since:

1.6

Author:

Doug Lea

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class edu.emory.mathcs.backport.java.util.AbstractMap

AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

Nested classes inherited from class java.util.Map

java.util.Map.Entry

Constructor Summary

ConcurrentSkipListMap()
Constructs a new, empty map, sorted according to the natural ordering of the keys.

ConcurrentSkipListMap(java.util.Comparator comparator)
Constructs a new, empty map, sorted according to the specified comparator.

ConcurrentSkipListMap(java.util.Map m)
Constructs a new map containing the same mappings as the given map, sorted according to the natural ordering of the keys.

ConcurrentSkipListMap(java.util.SortedMap m)
Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.

Method Summary

java.util.Map.Entry	ceilingEntry(java.lang.Object 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 entry.
java.lang.Object	ceilingKey(java.lang.Object key) Returns the least key greater than or equal to the given key, or null if there is no such key.
void	clear() Removes all of the mappings from this map.
java.lang.Object	clone() Returns a shallow copy of this ConcurrentSkipListMap instance.
java.util.Comparator	comparator()
boolean	containsKey(java.lang.Object key) Returns true if this map contains a mapping for the specified key.
boolean	containsValue(java.lang.Object value) Returns true if this map maps one or more keys to the specified value.
java.util.Set	descendingEntrySet() Returns a Set view of the mappings contained in this map.
java.util.Set	descendingKeySet() Returns a Set view of the keys contained in this map.
java.util.Set	entrySet() Returns a Set view of the mappings contained in this map.
boolean	equals(java.lang.Object o) Compares the specified object with this map for equality.
java.util.Map.Entry	firstEntry() Returns a key-value mapping associated with the least key in this map, or null if the map is empty.
java.lang.Object	firstKey()
java.util.Map.Entry	floorEntry(java.lang.Object 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.
java.lang.Object	floorKey(java.lang.Object key) Returns the greatest key less than or equal to the given key, or null if there is no such key.
java.lang.Object	get(java.lang.Object key) Returns the value to which the specified key is mapped, or if this map contains no mapping for the key.
java.util.SortedMap	headMap(java.lang.Object toKey) Equivalent to ConcurrentNavigableMap.navigableHeadMap(java.lang.Object).
java.util.Map.Entry	higherEntry(java.lang.Object 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.
java.lang.Object	higherKey(java.lang.Object key) Returns the least key strictly greater than the given key, or null if there is no such key.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
java.util.Set	keySet() Returns a Set view of the keys contained in this map.
java.util.Map.Entry	lastEntry() Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
java.lang.Object	lastKey()
java.util.Map.Entry	lowerEntry(java.lang.Object 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.
java.lang.Object	lowerKey(java.lang.Object key) Returns the greatest key strictly less than the given key, or null if there is no such key.
NavigableMap	navigableHeadMap(java.lang.Object toKey) Returns a view of the portion of this map whose keys are strictly less than toKey.
NavigableMap	navigableSubMap(java.lang.Object fromKey, java.lang.Object toKey) Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive.
NavigableMap	navigableTailMap(java.lang.Object fromKey) Returns a view of the portion of this map whose keys are greater than or equal to fromKey.
java.util.Map.Entry	pollFirstEntry() Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.
java.util.Map.Entry	pollLastEntry() Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Associates the specified value with the specified key in this map.
java.lang.Object	putIfAbsent(java.lang.Object key, java.lang.Object value) If the specified key is not already associated with a value, associate it with the given value. This is equivalent to if (!map.containsKey(key)) return map.put(key, value); else return map.get(key); except that the action is performed atomically.
java.lang.Object	remove(java.lang.Object key) Removes the mapping for the specified key from this map if present.
boolean	remove(java.lang.Object key, java.lang.Object value) Removes the entry for a key only if currently mapped to a given value. This is equivalent to if (map.containsKey(key) && map.get(key).equals(value)) { map.remove(key); return true; } else return false; except that the action is performed atomically.
java.lang.Object	replace(java.lang.Object key, java.lang.Object value) Replaces the entry for a key only if currently mapped to some value. This is equivalent to if (map.containsKey(key)) { return map.put(key, value); } else return null; except that the action is performed atomically.
boolean	replace(java.lang.Object key, java.lang.Object oldValue, java.lang.Object newValue) Replaces the entry for a key only if currently mapped to a given value. This is equivalent to if (map.containsKey(key) && map.get(key).equals(oldValue)) { map.put(key, newValue); return true; } else return false; except that the action is performed atomically.
int	size() Returns the number of key-value mappings in this map.
java.util.SortedMap	subMap(java.lang.Object fromKey, java.lang.Object toKey) Equivalent to ConcurrentNavigableMap.navigableSubMap(java.lang.Object, java.lang.Object).
java.util.SortedMap	tailMap(java.lang.Object fromKey) Equivalent to ConcurrentNavigableMap.navigableTailMap(java.lang.Object).
java.util.Collection	values() Returns a Collection view of the values contained in this map.

Methods inherited from class java.util.AbstractMap

hashCode, putAll, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

hashCode, putAll

Constructor Detail

ConcurrentSkipListMap

public ConcurrentSkipListMap()

Constructs a new, empty map, sorted according to the natural ordering of the keys.

ConcurrentSkipListMap

public ConcurrentSkipListMap(java.util.Comparator comparator)

Constructs a new, empty map, sorted according to the specified comparator.

Parameters:

comparator - the comparator that will be used to order this map. If null, the natural ordering of the keys will be used.

ConcurrentSkipListMap

public ConcurrentSkipListMap(java.util.Map m)

Constructs a new map containing the same mappings as the given map, sorted according to the natural ordering of the keys.

Parameters:

m - the map whose mappings are to be placed in this map

Throws:

java.lang.ClassCastException - if the keys in m are not Comparable, or are not mutually comparable

java.lang.NullPointerException - if the specified map or any of its keys or values are null

ConcurrentSkipListMap

public ConcurrentSkipListMap(java.util.SortedMap m)

Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.

Parameters:

m - the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map

Throws:

java.lang.NullPointerException - if the specified sorted map or any of its keys or values are null

Method Detail

clone

public java.lang.Object clone()

Returns a shallow copy of this ConcurrentSkipListMap instance. (The keys and values themselves are not cloned.)

Returns:

a shallow copy of this map

containsKey

public boolean containsKey(java.lang.Object key)

Returns true if this map contains a mapping for the specified key.

Specified by:

containsKey in interface java.util.Map

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

get

public java.lang.Object get(java.lang.Object key)

Returns the value to which the specified key is mapped, or if this map contains no mapping for the key.

More formally, if this map contains a mapping from a key to a value such that compares equal to according to the map's ordering, then this method returns ; otherwise it returns . (There can be at most one such mapping.)

Specified by:

get in interface java.util.Map

Parameters:

key - key whose associated value is to be returned

Returns:

the value to which this map maps the specified key, or null if the map contains no mapping for the key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced.

Specified by:

put in interface java.util.Map

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key or value is null

remove

public java.lang.Object remove(java.lang.Object key)

Removes the mapping for the specified key from this map if present.

Specified by:

remove in interface java.util.Map

Parameters:

key - key for which mapping should be removed

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

containsValue

public boolean containsValue(java.lang.Object value)

Returns true if this map maps one or more keys to the specified value. This operation requires time linear in the map size.

Specified by:

containsValue in interface java.util.Map

Parameters:

value - value whose presence in this map is to be tested

Returns:

true if a mapping to value exists; false otherwise

Throws:

java.lang.NullPointerException - if the specified value is null

size

public int size()

Returns the number of key-value mappings in this map. If this map contains more than Integer.MAX_VALUE elements, it returns Integer.MAX_VALUE.

Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.

Specified by:

size in interface java.util.Map

Returns:

the number of elements in this map

isEmpty

public boolean isEmpty()

Returns true if this map contains no key-value mappings.

Specified by:

isEmpty in interface java.util.Map

Returns:

true if this map contains no key-value mappings

clear

public void clear()

Removes all of the mappings from this map.

Specified by:

clear in interface java.util.Map

keySet

public java.util.Set keySet()

Returns a Set 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. 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.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

Specified by:

keySet in interface java.util.Map

Overrides:

keySet in class AbstractMap

Returns:

a set view of the keys contained in this map, sorted in ascending order

descendingKeySet

public java.util.Set descendingKeySet()

Returns a Set 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. 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.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

Specified by:

descendingKeySet in interface NavigableMap

Returns:

a set view of the keys contained in this map, sorted in descending order

values

public java.util.Collection values()

Returns a Collection view of the values contained in this map. The collection's iterator returns the values in ascending order of the corresponding keys. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

Specified by:

values in interface java.util.Map

entrySet

public java.util.Set entrySet()

Returns a Set view of the mappings contained in this map. The set's iterator returns the entries in ascending key order. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. 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.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

The Map.Entry elements returned by iterator.next() do not support the setValue operation.

Specified by:

entrySet in interface java.util.Map

Returns:

a set view of the mappings contained in this map, sorted in ascending key order

descendingEntrySet

public java.util.Set descendingEntrySet()

Returns a Set view of the mappings contained in this map. The set's iterator returns the entries in descending key order. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. 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.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

The Map.Entry elements returned by iterator.next() do not support the setValue operation.

Specified by:

descendingEntrySet in interface NavigableMap

Returns:

a set view of the mappings contained in this map, sorted in descending key order

equals

public boolean equals(java.lang.Object o)

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This operation may return misleading results if either map is concurrently modified during execution of this method.

Specified by:

equals in interface java.util.Map

Parameters:

o - object to be compared for equality with this map

Returns:

true if the specified object is equal to this map

putIfAbsent

public java.lang.Object putIfAbsent(java.lang.Object key,
                                    java.lang.Object value)

If the specified key is not already associated with a value, associate it with the given value. This is equivalent to

   if (!map.containsKey(key))
       return map.put(key, value);
   else
       return map.get(key);

except that the action is performed atomically.

Specified by:

putIfAbsent in interface ConcurrentMap

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key or value is null

remove

public boolean remove(java.lang.Object key,
                      java.lang.Object value)

Removes the entry for a key only if currently mapped to a given value. This is equivalent to

   if (map.containsKey(key) && map.get(key).equals(value)) {
       map.remove(key);
       return true;
   } else return false;

except that the action is performed atomically.

Specified by:

remove in interface ConcurrentMap

Parameters:

key - key with which the specified value is associated

value - value expected to be associated with the specified key

Returns:

true if the value was removed

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

replace

public boolean replace(java.lang.Object key,
                       java.lang.Object oldValue,
                       java.lang.Object newValue)

Replaces the entry for a key only if currently mapped to a given value. This is equivalent to

   if (map.containsKey(key) && map.get(key).equals(oldValue)) {
       map.put(key, newValue);
       return true;
   } else return false;

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMap

Parameters:

key - key with which the specified value is associated

oldValue - value expected to be associated with the specified key

newValue - value to be associated with the specified key

Returns:

true if the value was replaced

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if any of the arguments are null

replace

public java.lang.Object replace(java.lang.Object key,
                                java.lang.Object value)

Replaces the entry for a key only if currently mapped to some value. This is equivalent to

   if (map.containsKey(key)) {
       return map.put(key, value);
   } else return null;

except that the action is performed atomically.

Specified by:

replace in interface ConcurrentMap

Parameters:

key - key with which the specified value is associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key or value is null

comparator

public java.util.Comparator comparator()

Specified by:

comparator in interface java.util.SortedMap

firstKey

public java.lang.Object firstKey()

Specified by:

firstKey in interface java.util.SortedMap

Throws:

java.util.NoSuchElementException

lastKey

public java.lang.Object lastKey()

Specified by:

lastKey in interface java.util.SortedMap

Throws:

java.util.NoSuchElementException

navigableSubMap

public NavigableMap navigableSubMap(java.lang.Object fromKey,
                                    java.lang.Object toKey)

Description copied from interface: NavigableMap

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.

Specified by:

navigableSubMap in interface ConcurrentNavigableMap

Throws:

java.lang.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.

java.lang.NullPointerException - if fromKey or toKey is null

java.lang.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

navigableHeadMap

public NavigableMap navigableHeadMap(java.lang.Object toKey)

Description copied from interface: NavigableMap

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.

Specified by:

navigableHeadMap in interface ConcurrentNavigableMap

Throws:

java.lang.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.

java.lang.NullPointerException - if toKey is null

java.lang.IllegalArgumentException - if this map itself has a restricted range, and toKey lies outside the bounds of the range

navigableTailMap

public NavigableMap navigableTailMap(java.lang.Object fromKey)

Description copied from interface: NavigableMap

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.

Specified by:

navigableTailMap in interface ConcurrentNavigableMap

Throws:

java.lang.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.

java.lang.NullPointerException - if fromKey is null

java.lang.IllegalArgumentException - if this map itself has a restricted range, and fromKey lies outside the bounds of the range

subMap

public java.util.SortedMap subMap(java.lang.Object fromKey,
                                  java.lang.Object toKey)

Equivalent to ConcurrentNavigableMap.navigableSubMap(java.lang.Object, java.lang.Object).

Specified by:

subMap in interface ConcurrentNavigableMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException - if fromKey or toKey is null

java.lang.IllegalArgumentException

headMap

public java.util.SortedMap headMap(java.lang.Object toKey)

Equivalent to ConcurrentNavigableMap.navigableHeadMap(java.lang.Object).

Specified by:

headMap in interface ConcurrentNavigableMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException - if toKey is null

java.lang.IllegalArgumentException

tailMap

public java.util.SortedMap tailMap(java.lang.Object fromKey)

Equivalent to ConcurrentNavigableMap.navigableTailMap(java.lang.Object).

Specified by:

tailMap in interface ConcurrentNavigableMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException - if fromKey is null

java.lang.IllegalArgumentException

lowerEntry

public java.util.Map.Entry lowerEntry(java.lang.Object 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. The returned entry does not support the Entry.setValue method.

Specified by:

lowerEntry in interface NavigableMap

Parameters:

key - the key

Returns:

an entry with the greatest key less than key, or null if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

lowerKey

public java.lang.Object lowerKey(java.lang.Object key)

Description copied from interface: NavigableMap

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

Specified by:

lowerKey in interface NavigableMap

Parameters:

key - the key

Returns:

the greatest key less than key, or null if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

floorEntry

public java.util.Map.Entry floorEntry(java.lang.Object 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. The returned entry does not support the Entry.setValue method.

Specified by:

floorEntry in interface NavigableMap

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:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

floorKey

public java.lang.Object floorKey(java.lang.Object key)

Description copied from interface: NavigableMap

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

Specified by:

floorKey in interface NavigableMap

Parameters:

key - the key

Returns:

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

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

ceilingEntry

public java.util.Map.Entry ceilingEntry(java.lang.Object 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 entry. The returned entry does not support the Entry.setValue method.

Specified by:

ceilingEntry in interface NavigableMap

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:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

ceilingKey

public java.lang.Object ceilingKey(java.lang.Object key)

Description copied from interface: NavigableMap

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

Specified by:

ceilingKey in interface NavigableMap

Parameters:

key - the key

Returns:

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

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

higherEntry

public java.util.Map.Entry higherEntry(java.lang.Object 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. The returned entry does not support the Entry.setValue method.

Specified by:

higherEntry in interface NavigableMap

Parameters:

key - the key

Returns:

an entry with the least key greater than key, or null if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

higherKey

public java.lang.Object higherKey(java.lang.Object key)

Description copied from interface: NavigableMap

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

Specified by:

higherKey in interface NavigableMap

Parameters:

key - the key

Returns:

the least key greater than key, or null if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null

firstEntry

public java.util.Map.Entry firstEntry()

Returns a key-value mapping associated with the least key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.

Specified by:

firstEntry in interface NavigableMap

Returns:

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

lastEntry

public java.util.Map.Entry lastEntry()

Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.

Specified by:

lastEntry in interface NavigableMap

Returns:

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

pollFirstEntry

public java.util.Map.Entry pollFirstEntry()

Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.

Specified by:

pollFirstEntry in interface NavigableMap

Returns:

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

pollLastEntry

public java.util.Map.Entry pollLastEntry()

Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.

Specified by:

pollLastEntry in interface NavigableMap

Returns:

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