org.apache.jena.atlas.lib

Class RefCountingMap<K,T>

java.lang.Object

org.apache.jena.atlas.lib.RefCountingMap<K,T>

Type Parameters:

K -

T -

public class RefCountingMap<K,T>
extends Object

A key -> value 'map' which reference counts entries.

The same (key,value) pair can be added to the map several times and then removed several times. A reference count is incremented for each addition and, provided the count is greater than 0, decremented on removal.

The pair is removed from the map when a remove decrements the reference count to 0.

This class is thread safe.

Constructor Summary

Constructors

Constructor and Description
RefCountingMap()

Method Summary

Modifier and Type	Method and Description
void	add(K key, T value) Add a key value pair to the map.
void	clear() Clear the map of all keys regardless of reference counts.
boolean	contains(K key)
boolean	containsKey(Object key)
T	get(Object key) Return the value associated with a key in the map.
boolean	isEmpty()
Collection<K>	keys()
Set<K>	keySet()
int	refCount(K key) Return the reference count for the entry corresponding to a key in the map.
void	remove(K key) Decrement the reference count for a key, and remove the corresponding entry from the map if the result is 0.
void	removeAll(K key) Remove the entry corresponding to the key from the map completely.
int	size()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RefCountingMap

public RefCountingMap()

Method Detail

contains

public boolean contains(K key)

keys

public Collection<K> keys()

size

public int size()

isEmpty

public boolean isEmpty()

clear

public void clear()

Clear the map of all keys regardless of reference counts.

keySet

public Set<K> keySet()

containsKey

public boolean containsKey(Object key)

add

public void add(K key,
                T value)

Add a key value pair to the map.

if there is no entry in the map for the key, then a key value pair is added to the map with a reference count of 1.

If there is already an entry in the map for the same key and value, the reference count for that entry is incremented.

if there is an entry in the map for the key, but with a different value, then that entry is replaced with a new entry for the key and value with a reference count of 1.

Parameters:

key -

value -

remove

public void remove(K key)

Decrement the reference count for a key, and remove the corresponding entry from the map if the result is 0.

Do nothing if there is no entry in the map corresponding to the key.

Parameters:

key -

removeAll

public void removeAll(K key)

Remove the entry corresponding to the key from the map completely.

This method ignores the reference count.

Parameters:

key -

refCount

public int refCount(K key)

Return the reference count for the entry corresponding to a key in the map.

Returns 0 if there is no entry in the map corresponding to the key.

Parameters:

key -

Returns:

the reference count for the entry corresponding to key in the map, or 0 if there is no corresponding entry.

get

public T get(Object key)

Return the value associated with a key in the map.

Parameters:

key -

Returns:

the value associated with the key, or null if there is no such value.