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java.lang.Objectorg.apache.commons.collections.map.Flat3Map
A Map implementation that stores data in simple fields until
the size is greater than 3.
This map is designed for performance and can outstrip HashMap. It also has good garbage collection characteristics.
The performance gains on puts are due to not needing to create a Map Entry object. This is a large saving not only in performance but in garbage collection.
Whilst in flat mode this map is also easy for the garbage collector to dispatch. This is because it contains no complex objects or arrays which slow the progress.
Do not use Flat3Map if the size is likely to grow beyond 3.
| Nested Class Summary |
| Nested classes inherited from class java.util.Map |
Map.Entry |
| Constructor Summary | |
Flat3Map()
Constructor. |
|
Flat3Map(Map map)
Constructor copying elements from another map. |
|
| Method Summary | |
void |
clear()
Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues. |
Object |
clone()
Clones the map without cloning the keys or values. |
boolean |
containsKey(Object key)
Checks whether the map contains the specified key. |
boolean |
containsValue(Object value)
Checks whether the map contains the specified value. |
protected AbstractHashedMap |
createDelegateMap()
Create an instance of the map used for storage when in delegation mode. |
Set |
entrySet()
Gets the entrySet view of the map. |
boolean |
equals(Object obj)
Compares this map with another. |
Object |
get(Object key)
Gets the value mapped to the key specified. |
int |
hashCode()
Gets the standard Map hashCode. |
boolean |
isEmpty()
Checks whether the map is currently empty. |
Set |
keySet()
Gets the keySet view of the map. |
MapIterator |
mapIterator()
Gets an iterator over the map. |
Object |
put(Object key,
Object value)
Puts a key-value mapping into this map. |
void |
putAll(Map map)
Puts all the values from the specified map into this map. |
Object |
remove(Object key)
Removes the specified mapping from this map. |
int |
size()
Gets the size of the map. |
String |
toString()
Gets the map as a String. |
Collection |
values()
Gets the values view of the map. |
| Methods inherited from class java.lang.Object |
finalize, getClass, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
public Flat3Map()
public Flat3Map(Map map)
map - the map to copy
NullPointerException - if the map is null| Method Detail |
public Object get(Object key)
get in interface Mapkey - the key
public int size()
size in interface Mappublic boolean isEmpty()
isEmpty in interface Mappublic boolean containsKey(Object key)
containsKey in interface Mapkey - the key to search for
public boolean containsValue(Object value)
containsValue in interface Mapvalue - the value to search for
public Object put(Object key,
Object value)
put in interface Mapkey - the key to addvalue - the value to add
public void putAll(Map map)
putAll in interface Mapmap - the map to add
NullPointerException - if the map is nullprotected AbstractHashedMap createDelegateMap()
This can be overridden by subclasses to provide a different map implementation. Not every AbstractHashedMap is suitable, identity and reference based maps would be poor choices.
public Object remove(Object key)
remove in interface Mapkey - the mapping to remove
public void clear()
clear in interface Mappublic MapIterator mapIterator()
A MapIterator returns the keys in the map. It also provides convenient methods to get the key and value, and set the value. It avoids the need to create an entrySet/keySet/values object. It also avoids creating the Map Entry object.
mapIterator in interface IterableMappublic Set entrySet()
mapIterator().
entrySet in interface Mappublic Set keySet()
mapIterator().
keySet in interface Mappublic Collection values()
mapIterator().
values in interface Mappublic Object clone()
public boolean equals(Object obj)
equals in interface Mapobj - the object to compare to
public int hashCode()
hashCode in interface Mappublic String toString()
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