public class Flat3Map extends java.lang.Object implements IterableMap, java.io.Serializable, java.lang.Cloneable
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.
Note that Flat3Map is not synchronized and is not thread-safe.
If you wish to use this map from multiple threads concurrently, you must use
appropriate synchronization. The simplest approach is to wrap this map
using Collections.synchronizedMap(Map)
. This class may throw
exceptions when accessed by concurrent threads without synchronization.
Constructor and Description |
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Flat3Map()
Constructor.
|
Flat3Map(java.util.Map map)
Constructor copying elements from another map.
|
Modifier and Type | Method and Description |
---|---|
void |
clear()
Clears the map, resetting the size to zero and nullifying references
to avoid garbage collection issues.
|
java.lang.Object |
clone()
Clones the map without cloning the keys or values.
|
boolean |
containsKey(java.lang.Object key)
Checks whether the map contains the specified key.
|
boolean |
containsValue(java.lang.Object value)
Checks whether the map contains the specified value.
|
java.util.Set |
entrySet()
Gets the entrySet view of the map.
|
boolean |
equals(java.lang.Object obj)
Compares this map with another.
|
java.lang.Object |
get(java.lang.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.
|
java.util.Set |
keySet()
Gets the keySet view of the map.
|
MapIterator |
mapIterator()
Gets an iterator over the map.
|
java.lang.Object |
put(java.lang.Object key,
java.lang.Object value)
Puts a key-value mapping into this map.
|
void |
putAll(java.util.Map map)
Puts all the values from the specified map into this map.
|
java.lang.Object |
remove(java.lang.Object key)
Removes the specified mapping from this map.
|
int |
size()
Gets the size of the map.
|
java.lang.String |
toString()
Gets the map as a String.
|
java.util.Collection |
values()
Gets the values view of the map.
|
public Flat3Map()
public Flat3Map(java.util.Map map)
map
- the map to copyjava.lang.NullPointerException
- if the map is nullpublic java.lang.Object get(java.lang.Object key)
get
in interface java.util.Map
key
- the keypublic int size()
size
in interface java.util.Map
public boolean isEmpty()
isEmpty
in interface java.util.Map
public boolean containsKey(java.lang.Object key)
containsKey
in interface java.util.Map
key
- the key to search forpublic boolean containsValue(java.lang.Object value)
containsValue
in interface java.util.Map
value
- the value to search forpublic java.lang.Object put(java.lang.Object key, java.lang.Object value)
put
in interface java.util.Map
key
- the key to addvalue
- the value to addpublic void putAll(java.util.Map map)
putAll
in interface java.util.Map
map
- the map to addjava.lang.NullPointerException
- if the map is nullpublic java.lang.Object remove(java.lang.Object key)
remove
in interface java.util.Map
key
- the mapping to removepublic void clear()
clear
in interface java.util.Map
public 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 IterableMap
public java.util.Set entrySet()
mapIterator()
.entrySet
in interface java.util.Map
public java.util.Set keySet()
mapIterator()
.keySet
in interface java.util.Map
public java.util.Collection values()
mapIterator()
.values
in interface java.util.Map
public java.lang.Object clone()
clone
in class java.lang.Object
public boolean equals(java.lang.Object obj)
equals
in interface java.util.Map
equals
in class java.lang.Object
obj
- the object to compare topublic int hashCode()
hashCode
in interface java.util.Map
hashCode
in class java.lang.Object
public java.lang.String toString()
toString
in class java.lang.Object
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