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java.lang.Object | +--java.util.AbstractMap | +--java.util.TreeMap | +--org.apache.commons.collections.FastTreeMap
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 Declartion.
Constructor Summary | |
FastTreeMap()
Construct a an empty map. |
|
FastTreeMap(java.util.Comparator comparator)
Construct an empty map with the specified comparator. |
|
FastTreeMap(java.util.Map map)
Construct a new map with the same mappings as the specified map, sorted according to the keys's natural order |
|
FastTreeMap(java.util.SortedMap map)
Construct a new map with the same mappings as the specified map, sorted according to the same ordering |
Method Summary | |
void |
clear()
Remove all mappings from this map. |
java.lang.Object |
clone()
Return a shallow copy of this FastTreeMap instance. |
java.util.Comparator |
comparator()
Return the comparator used to order this map, or null
if this map uses its keys' natural order. |
boolean |
containsKey(java.lang.Object key)
Return true if this map contains a mapping for the
specified key. |
boolean |
containsValue(java.lang.Object value)
Return true if this map contains one or more keys mapping
to the specified value. |
java.util.Set |
entrySet()
Return a collection view of the mappings contained in this map. |
boolean |
equals(java.lang.Object o)
Compare the specified object with this list for equality. |
java.lang.Object |
firstKey()
Return the first (lowest) key currently in this sorted map. |
java.lang.Object |
get(java.lang.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. |
java.util.SortedMap |
headMap(java.lang.Object key)
Return a view of the portion of this map whose keys are strictly less than the specified key. |
boolean |
isEmpty()
Test if this list has no elements. |
java.util.Set |
keySet()
Return a set view of the keys contained in this map. |
java.lang.Object |
lastKey()
Return the last (highest) key currently in this sorted map. |
java.lang.Object |
put(java.lang.Object key,
java.lang.Object value)
Associate the specified value with the specified key in this map. |
void |
putAll(java.util.Map in)
Copy all of the mappings from the specified map to this one, replacing any mappings with the same keys. |
java.lang.Object |
remove(java.lang.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. |
java.util.SortedMap |
subMap(java.lang.Object fromKey,
java.lang.Object toKey)
Return a view of the portion of this map whose keys are in the range fromKey (inclusive) to toKey (exclusive). |
java.util.SortedMap |
tailMap(java.lang.Object key)
Return a view of the portion of this map whose keys are greater than or equal to the specified key. |
java.util.Collection |
values()
Return a collection view of the values contained in this map. |
Methods inherited from class java.util.AbstractMap |
toString |
Methods inherited from class java.lang.Object |
getClass, notify, notifyAll, wait, wait, wait |
Constructor Detail |
public FastTreeMap()
public FastTreeMap(java.util.Comparator comparator)
comparator
- The comparator to use for ordering tree elementspublic FastTreeMap(java.util.Map map)
map
- The map whose mappings are to be copiedpublic FastTreeMap(java.util.SortedMap map)
map
- The map whose mappings are to be copiedMethod Detail |
public boolean getFast()
public void setFast(boolean fast)
fast
- true if this map should operate in fast modepublic void clear()
clear
in interface java.util.Map
clear
in class java.util.TreeMap
public java.lang.Object clone()
FastTreeMap
instance.
The keys and values themselves are not copied.
clone
in class java.util.TreeMap
public java.util.Comparator comparator()
null
if this map uses its keys' natural order.
comparator
in interface java.util.SortedMap
comparator
in class java.util.TreeMap
public boolean containsKey(java.lang.Object key)
true
if this map contains a mapping for the
specified key.
containsKey
in interface java.util.Map
containsKey
in class java.util.TreeMap
key
- Key to be searched forpublic boolean containsValue(java.lang.Object value)
true
if this map contains one or more keys mapping
to the specified value.
containsValue
in interface java.util.Map
containsValue
in class java.util.TreeMap
value
- Value to be searched forpublic java.util.Set entrySet()
Map.Entry
.
entrySet
in interface java.util.Map
entrySet
in class java.util.TreeMap
public boolean equals(java.lang.Object o)
Map.equals
method.
equals
in interface java.util.Map
equals
in class java.util.AbstractMap
o
- Object to be compared to this listpublic java.lang.Object firstKey()
firstKey
in interface java.util.SortedMap
firstKey
in class java.util.TreeMap
public java.lang.Object get(java.lang.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.
get
in interface java.util.Map
get
in class java.util.TreeMap
key
- Key whose value is to be returnedpublic int hashCode()
Map.hashCode
method.
hashCode
in interface java.util.Map
hashCode
in class java.util.AbstractMap
public java.util.SortedMap headMap(java.lang.Object key)
headMap
in interface java.util.SortedMap
headMap
in class java.util.TreeMap
key
- Key higher than any in the returned mappublic boolean isEmpty()
isEmpty
in interface java.util.Map
isEmpty
in class java.util.AbstractMap
public java.util.Set keySet()
keySet
in interface java.util.Map
keySet
in class java.util.TreeMap
public java.lang.Object lastKey()
lastKey
in interface java.util.SortedMap
lastKey
in class java.util.TreeMap
public java.lang.Object put(java.lang.Object key, java.lang.Object value)
put
in interface java.util.Map
put
in class java.util.TreeMap
key
- The key with which the value is to be associatedvalue
- The value to be associated with this keypublic void putAll(java.util.Map in)
putAll
in interface java.util.Map
putAll
in class java.util.TreeMap
in
- Map whose mappings are to be copiedpublic java.lang.Object remove(java.lang.Object key)
remove
in interface java.util.Map
remove
in class java.util.TreeMap
key
- Key whose mapping is to be removedpublic int size()
size
in interface java.util.Map
size
in class java.util.TreeMap
public java.util.SortedMap subMap(java.lang.Object fromKey, java.lang.Object toKey)
subMap
in interface java.util.SortedMap
subMap
in class java.util.TreeMap
fromKey
- Lower limit of keys for the returned maptoKey
- Upper limit of keys for the returned mappublic java.util.SortedMap tailMap(java.lang.Object key)
tailMap
in interface java.util.SortedMap
tailMap
in class java.util.TreeMap
key
- Key less than or equal to any in the returned mappublic java.util.Collection values()
values
in interface java.util.Map
values
in class java.util.TreeMap
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