org.apache.commons.collections4.map

Class AbstractReferenceMap.ReferenceEntry<K,V>

java.lang.Object

org.apache.commons.collections4.map.AbstractHashedMap.HashEntry<K,V>

org.apache.commons.collections4.map.AbstractReferenceMap.ReferenceEntry<K,V>

All Implemented Interfaces:

Map.Entry<K,V>, KeyValue<K,V>

Enclosing class:

AbstractReferenceMap<K,V>

protected static class AbstractReferenceMap.ReferenceEntry<K,V>
extends AbstractHashedMap.HashEntry<K,V>

A MapEntry implementation for the map.

If getKey() or getValue() returns null, it means the mapping is stale and should be removed.

Since:

3.1

Field Summary

Fields inherited from class org.apache.commons.collections4.map.AbstractHashedMap.HashEntry

hashCode, key, next, value

Constructor Summary

Constructors

Constructor and Description
ReferenceEntry(AbstractReferenceMap<K,V> parent, AbstractHashedMap.HashEntry<K,V> next, int hashCode, K key, V value) Creates a new entry object for the ReferenceMap.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj) Compares this map entry to another.
K	getKey() Gets the key from the entry.
V	getValue() Gets the value from the entry.
int	hashCode() Gets the hashcode of the entry using temporary hard references.
protected AbstractReferenceMap.ReferenceEntry<K,V>	next() Gets the next entry in the bucket.
protected void	nullValue() This method can be overriden to provide custom logic to purge value
protected void	onPurge() This is the callback for custom "after purge" logic
protected boolean	purge(Reference<?> ref) Purges the specified reference
V	setValue(V obj) Sets the value of the entry.
protected <T> Object	toReference(AbstractReferenceMap.ReferenceStrength type, T referent, int hash) Constructs a reference of the given type to the given referent.

Methods inherited from class org.apache.commons.collections4.map.AbstractHashedMap.HashEntry

toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map.Entry

comparingByKey, comparingByKey, comparingByValue, comparingByValue

Constructor Detail

ReferenceEntry

public ReferenceEntry(AbstractReferenceMap<K,V> parent,
                      AbstractHashedMap.HashEntry<K,V> next,
                      int hashCode,
                      K key,
                      V value)

Creates a new entry object for the ReferenceMap.

Parameters:

parent - the parent map

next - the next entry in the hash bucket

hashCode - the hash code of the key

key - the key

value - the value

Method Detail

getKey

public K getKey()

Gets the key from the entry. This method dereferences weak and soft keys and thus may return null.

Specified by:

getKey in interface Map.Entry<K,V>

Specified by:

getKey in interface KeyValue<K,V>

Overrides:

getKey in class AbstractHashedMap.HashEntry<K,V>

Returns:

the key, which may be null if it was garbage collected

getValue

public V getValue()

Gets the value from the entry. This method dereferences weak and soft value and thus may return null.

Specified by:

getValue in interface Map.Entry<K,V>

Specified by:

getValue in interface KeyValue<K,V>

Overrides:

getValue in class AbstractHashedMap.HashEntry<K,V>

Returns:

the value, which may be null if it was garbage collected

setValue

public V setValue(V obj)

Sets the value of the entry.

Specified by:

setValue in interface Map.Entry<K,V>

Overrides:

setValue in class AbstractHashedMap.HashEntry<K,V>

Parameters:

obj - the object to store

Returns:

the previous value

equals

public boolean equals(Object obj)

Compares this map entry to another.

This implementation uses isEqualKey and isEqualValue on the main map for comparison.

Specified by:

equals in interface Map.Entry<K,V>

Overrides:

equals in class AbstractHashedMap.HashEntry<K,V>

Parameters:

obj - the other map entry to compare to

Returns:

true if equal, false if not

hashCode

public int hashCode()

Gets the hashcode of the entry using temporary hard references.

This implementation uses hashEntry on the main map.

Specified by:

hashCode in interface Map.Entry<K,V>

Overrides:

hashCode in class AbstractHashedMap.HashEntry<K,V>

Returns:

the hashcode of the entry

toReference

protected <T> Object toReference(AbstractReferenceMap.ReferenceStrength type,
                                 T referent,
                                 int hash)

Constructs a reference of the given type to the given referent. The reference is registered with the queue for later purging.

Type Parameters:

T - the type of the referenced object

Parameters:

type - HARD, SOFT or WEAK

referent - the object to refer to

hash - the hash code of the key of the mapping; this number might be different from referent.hashCode() if the referent represents a value and not a key

Returns:

the reference to the object

onPurge

protected void onPurge()

This is the callback for custom "after purge" logic

purge

protected boolean purge(Reference<?> ref)

Purges the specified reference

Parameters:

ref - the reference to purge

Returns:

true or false

next

protected AbstractReferenceMap.ReferenceEntry<K,V> next()

Gets the next entry in the bucket.

Returns:

the next entry in the bucket

nullValue

protected void nullValue()

This method can be overriden to provide custom logic to purge value