public class FastTreeMap extends TreeMap
A customized implementation of java.util.TreeMap
designed
to operate in a multithreaded environment where the large majority of
method calls are read-only, instead of structural changes. When operating
in "fast" mode, read calls are non-synchronized and write calls perform the
following steps:
When first created, objects of this class default to "slow" mode, where
all accesses of any type are synchronized but no cloning takes place. This
is appropriate for initially populating the collection, followed by a switch
to "fast" mode (by calling setFast(true)
) after initialization
is complete.
NOTE: If you are creating and accessing a
TreeMap
only within a single thread, you should use
java.util.TreeMap
directly (with no synchronization), for
maximum performance.
NOTE: This class is not cross-platform. Using it may cause unexpected failures on some architectures. It suffers from the same problems as the double-checked locking idiom. In particular, the instruction that clones the internal collection and the instruction that sets the internal reference to the clone can be executed or perceived out-of-order. This means that any read operation might fail unexpectedly, as it may be reading the state of the internal collection before the internal collection is fully formed. For more information on the double-checked locking idiom, see the Double-Checked Locking Idiom Is Broken Declaration.
AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry
Modifier and Type | Field and Description |
---|---|
protected boolean |
fast
Are we operating in "fast" mode?
|
protected TreeMap |
map
The underlying map we are managing.
|
Constructor and Description |
---|
FastTreeMap()
Construct a an empty map.
|
FastTreeMap(Comparator comparator)
Construct an empty map with the specified comparator.
|
FastTreeMap(Map map)
Construct a new map with the same mappings as the specified map,
sorted according to the keys's natural order
|
FastTreeMap(SortedMap map)
Construct a new map with the same mappings as the specified map,
sorted according to the same ordering
|
Modifier and Type | Method and Description |
---|---|
void |
clear()
Remove all mappings from this map.
|
Object |
clone()
Return a shallow copy of this
FastTreeMap instance. |
Comparator |
comparator()
Return the comparator used to order this map, or
null
if this map uses its keys' natural order. |
boolean |
containsKey(Object key)
Return
true if this map contains a mapping for the
specified key. |
boolean |
containsValue(Object value)
Return
true if this map contains one or more keys mapping
to the specified value. |
Set |
entrySet()
Return a collection view of the mappings contained in this map.
|
boolean |
equals(Object o)
Compare the specified object with this list for equality.
|
Object |
firstKey()
Return the first (lowest) key currently in this sorted map.
|
Object |
get(Object key)
Return the value to which this map maps the specified key.
|
boolean |
getFast()
Returns true if this map is operating in fast mode.
|
int |
hashCode()
Return the hash code value for this map.
|
SortedMap |
headMap(Object key)
Return a view of the portion of this map whose keys are strictly
less than the specified key.
|
boolean |
isEmpty()
Return
true if this map contains no mappings. |
Set |
keySet()
Return a set view of the keys contained in this map.
|
Object |
lastKey()
Return the last (highest) key currently in this sorted map.
|
Object |
put(Object key,
Object value)
Associate the specified value with the specified key in this map.
|
void |
putAll(Map in)
Copy all of the mappings from the specified map to this one, replacing
any mappings with the same keys.
|
Object |
remove(Object key)
Remove any mapping for this key, and return any previously
mapped value.
|
void |
setFast(boolean fast)
Sets whether this map is operating in fast mode.
|
int |
size()
Return the number of key-value mappings in this map.
|
SortedMap |
subMap(Object fromKey,
Object toKey)
Return a view of the portion of this map whose keys are in the
range fromKey (inclusive) to toKey (exclusive).
|
SortedMap |
tailMap(Object key)
Return a view of the portion of this map whose keys are greater than
or equal to the specified key.
|
Collection |
values()
Return a collection view of the values contained in this map.
|
ceilingEntry, ceilingKey, descendingKeySet, descendingMap, firstEntry, floorEntry, floorKey, headMap, higherEntry, higherKey, lastEntry, lowerEntry, lowerKey, navigableKeySet, pollFirstEntry, pollLastEntry, subMap, tailMap
toString
protected TreeMap map
protected boolean fast
public FastTreeMap()
public FastTreeMap(Comparator comparator)
comparator
- the comparator to use for ordering tree elementspublic FastTreeMap(Map map)
map
- the map whose mappings are to be copiedpublic FastTreeMap(SortedMap map)
map
- the map whose mappings are to be copiedpublic boolean getFast()
public void setFast(boolean fast)
fast
- true if this map should operate in fast modepublic Object get(Object key)
null
if the map contains no mapping for this key, or if
there is a mapping with a value of null
. Use the
containsKey()
method to disambiguate these cases.public int size()
public boolean isEmpty()
true
if this map contains no mappings.isEmpty
in interface Map
isEmpty
in class AbstractMap
public boolean containsKey(Object key)
true
if this map contains a mapping for the
specified key.containsKey
in interface Map
containsKey
in class TreeMap
key
- the key to be searched forpublic boolean containsValue(Object value)
true
if this map contains one or more keys mapping
to the specified value.containsValue
in interface Map
containsValue
in class TreeMap
value
- the value to be searched forpublic Comparator comparator()
null
if this map uses its keys' natural order.comparator
in interface SortedMap
comparator
in class TreeMap
public Object firstKey()
public Object lastKey()
public Object put(Object key, Object value)
public void putAll(Map in)
public Object remove(Object key)
public void clear()
public boolean equals(Object o)
Map.equals
method.equals
in interface Map
equals
in class AbstractMap
o
- the object to be compared to this listpublic int hashCode()
Map.hashCode
method.hashCode
in interface Map
hashCode
in class AbstractMap
public Object clone()
FastTreeMap
instance.
The keys and values themselves are not copied.public SortedMap headMap(Object key)
public SortedMap subMap(Object fromKey, Object toKey)
public SortedMap tailMap(Object key)
public Set entrySet()
Map.Entry
.public Set keySet()
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