org.compass.core.util.backport.java.util.concurrent
Class ConcurrentSkipListMap

java.lang.Object
  java.util.AbstractMap
      org.compass.core.util.backport.java.util.AbstractMap
          org.compass.core.util.backport.java.util.concurrent.ConcurrentSkipListMap

All Implemented Interfaces:

Serializable, Cloneable, Map, SortedMap, ConcurrentMap, ConcurrentNavigableMap, NavigableMap

public class ConcurrentSkipListMap
extends AbstractMap
implements ConcurrentNavigableMap, Cloneable, 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

(package private) static class	ConcurrentSkipListMap.ComparableUsingComparator Represents a key with a comparator as a Comparable.
(package private) class	ConcurrentSkipListMap.EntryIterator
(package private) static class	ConcurrentSkipListMap.EntrySet
(package private) static class	ConcurrentSkipListMap.HeadIndex Nodes heading each level keep track of their level.
(package private) static class	ConcurrentSkipListMap.Index Index nodes represent the levels of the skip list.
(package private) class	ConcurrentSkipListMap.Iter Base of iterator classes:
(package private) class	ConcurrentSkipListMap.KeyIterator
(package private) static class	ConcurrentSkipListMap.KeySet
(package private) static class	ConcurrentSkipListMap.Node Nodes hold keys and values, and are singly linked in sorted order, possibly with some intervening marker nodes.
(package private) static class	ConcurrentSkipListMap.SubMap Submaps returned by ConcurrentSkipListMap submap operations represent a subrange of mappings of their underlying maps.
(package private) class	ConcurrentSkipListMap.ValueIterator
(package private) static class	ConcurrentSkipListMap.Values

Nested classes/interfaces inherited from class org.compass.core.util.backport.java.util.AbstractMap

AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

Constructor Summary

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

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

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

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

Method Summary

Map.Entry	ceilingEntry(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.
Object	ceilingKey(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.
Object	clone() Returns a shallow copy of this ConcurrentSkipListMap instance.
Comparator	comparator()
(package private) int	compare(Object k1, Object k2) Compares using comparator or natural ordering.
boolean	containsKey(Object key) Returns true if this map contains a mapping for the specified key.
boolean	containsValue(Object value) Returns true if this map maps one or more keys to the specified value.
NavigableSet	descendingKeySet() Returns a reverse order NavigableSet view of the keys contained in this map.
NavigableMap	descendingMap() Returns a reverse order view of the mappings contained in this map.
(package private) Object	doRemove(Object okey, Object value) Main deletion method.
(package private) Map.Entry	doRemoveFirstEntry() Removes first entry; returns its snapshot.
(package private) Map.Entry	doRemoveLastEntry() Removes last entry; returns its snapshot.
(package private) Iterator	entryIterator()
Set	entrySet() Returns a Set view of the mappings contained in this map.
boolean	equals(Object o) Compares the specified object with this map for equality.
(package private) ConcurrentSkipListMap.Node	findFirst() Specialized variant of findNode to get first valid node.
(package private) ConcurrentSkipListMap.Node	findLast() Specialized version of find to get last valid node.
(package private) ConcurrentSkipListMap.Node	findNear(Object kkey, int rel) Utility for ceiling, floor, lower, higher methods.
Map.Entry	firstEntry() Returns a key-value mapping associated with the least key in this map, or null if the map is empty.
Object	firstKey()
Map.Entry	floorEntry(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.
Object	floorKey(Object key) Returns the greatest key less than or equal to the given key, or null if there is no such key.
Object	get(Object key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
(package private) AbstractMap.SimpleImmutableEntry	getNear(Object key, int rel) Returns SimpleImmutableEntry for results of findNear.
SortedMap	headMap(Object toKey) Equivalent to headMap(toKey, false).
NavigableMap	headMap(Object 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.
Map.Entry	higherEntry(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.
Object	higherKey(Object key) Returns the least key strictly greater than the given key, or null if there is no such key.
(package private) boolean	inHalfOpenRange(Object key, Object least, Object fence) Returns true if given key greater than or equal to least and strictly less than fence, bypassing either test if least or fence are null.
(package private) void	initialize() Initializes or resets state.
(package private) boolean	inOpenRange(Object key, Object least, Object fence) Returns true if given key greater than or equal to least and less or equal to fence.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
(package private) Iterator	keyIterator()
Set	keySet() Returns a NavigableSet view of the keys contained in this map.
Map.Entry	lastEntry() Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
Object	lastKey()
Map.Entry	lowerEntry(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.
Object	lowerKey(Object key) Returns the greatest key strictly less than the given key, or null if there is no such key.
NavigableSet	navigableKeySet() Returns a NavigableSet view of the keys contained in this map.
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.
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.
Object	put(Object key, Object value) Associates the specified value with the specified key in this map.
Object	putIfAbsent(Object key, Object value) If the specified key is not already associated with a value, associate it with the given value.
Object	remove(Object key) Removes the mapping for the specified key from this map if present.
boolean	remove(Object key, Object value) Removes the entry for a key only if currently mapped to a given value.
Object	replace(Object key, Object value) Replaces the entry for a key only if currently mapped to some value.
boolean	replace(Object key, Object oldValue, Object newValue) Replaces the entry for a key only if currently mapped to a given value.
int	size() Returns the number of key-value mappings in this map.
NavigableMap	subMap(Object fromKey, boolean fromInclusive, Object toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range from fromKey to toKey.
SortedMap	subMap(Object fromKey, Object toKey) Equivalent to subMap(fromKey, true, toKey, false).
SortedMap	tailMap(Object fromKey) Equivalent to tailMap(fromKey, true).
NavigableMap	tailMap(Object 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.
(package private) Iterator	valueIterator()
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

Constructor Detail

ConcurrentSkipListMap

public ConcurrentSkipListMap()

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

ConcurrentSkipListMap

public ConcurrentSkipListMap(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(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:

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

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

ConcurrentSkipListMap

public ConcurrentSkipListMap(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:

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

Method Detail

initialize

final void initialize()

Initializes or resets state. Needed by constructors, clone, clear, readObject. and ConcurrentSkipListSet.clone. (Note that comparator must be separately initialized.)

compare

int compare(Object k1,
            Object k2)
      throws ClassCastException

Compares using comparator or natural ordering. Used when the ComparableUsingComparator approach doesn't apply.

Throws:

ClassCastException

inHalfOpenRange

boolean inHalfOpenRange(Object key,
                        Object least,
                        Object fence)

Returns true if given key greater than or equal to least and strictly less than fence, bypassing either test if least or fence are null. Needed mainly in submap operations.

inOpenRange

boolean inOpenRange(Object key,
                    Object least,
                    Object fence)

Returns true if given key greater than or equal to least and less or equal to fence. Needed mainly in submap operations.

doRemove

final Object doRemove(Object okey,
                      Object value)

Main deletion method. Locates node, nulls value, appends a deletion marker, unlinks predecessor, removes associated index nodes, and possibly reduces head index level. Index nodes are cleared out simply by calling findPredecessor. which unlinks indexes to deleted nodes found along path to key, which will include the indexes to this node. This is done unconditionally. We can't check beforehand whether there are index nodes because it might be the case that some or all indexes hadn't been inserted yet for this node during initial search for it, and we'd like to ensure lack of garbage retention, so must call to be sure.

Parameters:

okey - the key

value - if non-null, the value that must be associated with key

Returns:

the node, or null if not found

findFirst

ConcurrentSkipListMap.Node findFirst()

Specialized variant of findNode to get first valid node.

Returns:

first node or null if empty

doRemoveFirstEntry

Map.Entry doRemoveFirstEntry()

Removes first entry; returns its snapshot.

Returns:

null if empty, else snapshot of first entry

findLast

ConcurrentSkipListMap.Node findLast()

Specialized version of find to get last valid node.

Returns:

last node or null if empty

doRemoveLastEntry

Map.Entry doRemoveLastEntry()

Removes last entry; returns its snapshot. Specialized variant of doRemove.

Returns:

null if empty, else snapshot of last entry

findNear

ConcurrentSkipListMap.Node findNear(Object kkey,
                                    int rel)

Utility for ceiling, floor, lower, higher methods.

Parameters:

kkey - the key

rel - the relation -- OR'ed combination of EQ, LT, GT

Returns:

nearest node fitting relation, or null if no such

getNear

AbstractMap.SimpleImmutableEntry getNear(Object key,
                                         int rel)

Returns SimpleImmutableEntry for results of findNear.

Parameters:

key - the key

rel - the relation -- OR'ed combination of EQ, LT, GT

Returns:

Entry fitting relation, or null if no such

clone

public Object clone()

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

Overrides:

clone in class AbstractMap

Returns:

a shallow copy of this map

containsKey

public boolean containsKey(Object key)

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

Specified by:

containsKey in interface Map

Overrides:

containsKey in class AbstractMap

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:

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

NullPointerException - if the specified key is null

get

public Object get(Object key)

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

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

Specified by:

get in interface Map

Overrides:

get in class AbstractMap

Throws:

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

NullPointerException - if the specified key is null

put

public Object put(Object key,
                  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 Map

Overrides:

put in class AbstractMap

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:

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

NullPointerException - if the specified key or value is null

remove

public Object remove(Object key)

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

Specified by:

remove in interface Map

Overrides:

remove in class AbstractMap

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:

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

NullPointerException - if the specified key is null

containsValue

public boolean containsValue(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 Map

Overrides:

containsValue in class AbstractMap

Parameters:

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

Returns:

true if a mapping to value exists; false otherwise

Throws:

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 Map

Overrides:

size in class AbstractMap

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 Map

Overrides:

isEmpty in class AbstractMap

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 Map

Overrides:

clear in class AbstractMap

keySet

public Set keySet()

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. 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.

This method is equivalent to method navigableKeySet.

Specified by:

keySet in interface Map

Specified by:

keySet in interface ConcurrentNavigableMap

Overrides:

keySet in class AbstractMap

Returns:

a navigable set view of the keys in this map

navigableKeySet

public NavigableSet navigableKeySet()

Description copied from interface: ConcurrentNavigableMap

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. 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:

navigableKeySet in interface ConcurrentNavigableMap

Specified by:

navigableKeySet in interface NavigableMap

Returns:

a navigable set view of the keys in this map

values

public 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 Map

Overrides:

values in class AbstractMap

entrySet

public 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 Map

Specified by:

entrySet in class AbstractMap

Returns:

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

descendingMap

public NavigableMap descendingMap()

Description copied from interface: ConcurrentNavigableMap

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.

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.

Specified by:

descendingMap in interface ConcurrentNavigableMap

Specified by:

descendingMap in interface NavigableMap

Returns:

a reverse order view of this map

descendingKeySet

public NavigableSet descendingKeySet()

Description copied from interface: ConcurrentNavigableMap

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. 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 ConcurrentNavigableMap

Specified by:

descendingKeySet in interface NavigableMap

Returns:

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

equals

public boolean equals(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 Map

Overrides:

equals in class AbstractMap

Parameters:

o - object to be compared for equality with this map

Returns:

true if the specified object is equal to this map

putIfAbsent

public Object putIfAbsent(Object key,
                          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:

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

NullPointerException - if the specified key or value is null

remove

public boolean remove(Object key,
                      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:

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

NullPointerException - if the specified key is null

replace

public boolean replace(Object key,
                       Object oldValue,
                       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:

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

NullPointerException - if any of the arguments are null

replace

public Object replace(Object key,
                      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:

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

NullPointerException - if the specified key or value is null

comparator

public Comparator comparator()

Specified by:

comparator in interface SortedMap

firstKey

public Object firstKey()

Specified by:

firstKey in interface SortedMap

Throws:

NoSuchElementException

lastKey

public Object lastKey()

Specified by:

lastKey in interface SortedMap

Throws:

NoSuchElementException

subMap

public NavigableMap subMap(Object fromKey,
                           boolean fromInclusive,
                           Object toKey,
                           boolean toInclusive)

Description copied from interface: NavigableMap

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.

Specified by:

subMap in interface ConcurrentNavigableMap

Specified by:

subMap in interface NavigableMap

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

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

headMap

public NavigableMap headMap(Object toKey,
                            boolean inclusive)

Description copied from interface: NavigableMap

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.

Specified by:

headMap in interface ConcurrentNavigableMap

Specified by:

headMap in interface NavigableMap

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

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

tailMap

public NavigableMap tailMap(Object fromKey,
                            boolean inclusive)

Description copied from interface: NavigableMap

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.

Specified by:

tailMap in interface ConcurrentNavigableMap

Specified by:

tailMap in interface NavigableMap

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

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

subMap

public SortedMap subMap(Object fromKey,
                        Object toKey)

Description copied from interface: NavigableMap

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

Specified by:

subMap in interface SortedMap

Specified by:

subMap in interface ConcurrentNavigableMap

Specified by:

subMap in interface NavigableMap

Throws:

ClassCastException

NullPointerException - if fromKey or toKey is null

IllegalArgumentException

headMap

public SortedMap headMap(Object toKey)

Description copied from interface: NavigableMap

Equivalent to headMap(toKey, false).

Specified by:

headMap in interface SortedMap

Specified by:

headMap in interface ConcurrentNavigableMap

Specified by:

headMap in interface NavigableMap

Throws:

ClassCastException

NullPointerException - if toKey is null

IllegalArgumentException

tailMap

public SortedMap tailMap(Object fromKey)

Description copied from interface: NavigableMap

Equivalent to tailMap(fromKey, true).

Specified by:

tailM