org.jboss.cache.util
Class DeltaMap<K,V>

java.lang.Object
  java.util.AbstractMap<K,V>
      org.jboss.cache.util.DeltaMap<K,V>

Type Parameters:

K - key type

V - value type

All Implemented Interfaces:

java.util.Map<K,V>

public class DeltaMap<K,V>
extends java.util.AbstractMap<K,V>

Wraps an existing map, which is not modified, reflecting modifications in an internal modification set.

This is to minimize the amount of data copying, for instance in the case few changes are applied.

Example usage:

 HashMap<String, String> hm = new HashMap<String, String>();
 hm.put("a", "apple");
 DeltaMap dm = DeltaMap.create(hm);
 dm.remove("a");
 assert hm.containsKey("a");
 assert !dm.containsKey("a");
 dm.commit();
 assert !hm.containsKey("a");
 

Author:

Elias Ross

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Method Summary

void	clear()
void	commit() Commits the changes to the original map.
boolean	containsKey(java.lang.Object key)
static <K,V> DeltaMap<K,V>	create() Creates and returns a DeltaMap for an empty map.
static <K,V> DeltaMap<K,V>	create(java.util.Map<K,V> original) Creates and returns a DeltaMap for an original map.
java.util.Set<java.util.Map.Entry<K,V>>	entrySet()
static <K,V> DeltaMap<K,V>	excludeKeys(java.util.Map<K,V> original, K... exclude) Creates and returns a DeltaMap for an original map, excluding some key mappings.
static <K,V> DeltaMap<K,V>	excludeKeys(java.util.Map<K,V> original, java.util.Set<K> exclude) Creates and returns a DeltaMap for an original map, excluding some key mappings.
V	get(java.lang.Object key)
java.util.Map<K,V>	getChanged() Returns a Map of the entries changed, not including those removed.
java.util.Map<K,V>	getOriginal() Returns the original wrapped Map.
java.util.Set<K>	getRemoved() Returns the entries removed, including entries excluded by the constructor.
boolean	isModified() Returns true if the internal map was modified.
V	put(K key, V value)
V	remove(java.lang.Object key)
void	setOriginal(java.util.Map<K,V> original) Sets the original values of this delta map.
int	size()
java.lang.String	toDebugString() Returns a debug string.

Methods inherited from class java.util.AbstractMap

clone, containsValue, equals, hashCode, isEmpty, keySet, putAll, toString, values

Methods inherited from class java.lang.Object

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

Method Detail

create

public static <K,V> DeltaMap<K,V> create(java.util.Map<K,V> original)

Creates and returns a DeltaMap for an original map.

Parameters:

original - will not be modified, except by commit()

Returns:

a new instance

create

public static <K,V> DeltaMap<K,V> create()

Creates and returns a DeltaMap for an empty map.

Returns:

a new instance

excludeKeys

public static <K,V> DeltaMap<K,V> excludeKeys(java.util.Map<K,V> original,
                                              java.util.Set<K> exclude)

Creates and returns a DeltaMap for an original map, excluding some key mappings.

Parameters:

original - will not be modified, except by commit()

exclude - entries not to include

Returns:

a new instance

excludeKeys

public static <K,V> DeltaMap<K,V> excludeKeys(java.util.Map<K,V> original,
                                              K... exclude)

Creates and returns a DeltaMap for an original map, excluding some key mappings.

entrySet

public java.util.Set<java.util.Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface java.util.Map<K,V>

Specified by:

entrySet in class java.util.AbstractMap<K,V>

size

public int size()

Specified by:

size in interface java.util.Map<K,V>

Overrides:

size in class java.util.AbstractMap<K,V>

containsKey

public boolean containsKey(java.lang.Object key)

Specified by:

containsKey in interface java.util.Map<K,V>

Overrides:

containsKey in class java.util.AbstractMap<K,V>

get

public V get(java.lang.Object key)

Specified by:

get in interface java.util.Map<K,V>

Overrides:

get in class java.util.AbstractMap<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface java.util.Map<K,V>

Overrides:

put in class java.util.AbstractMap<K,V>

remove

public V remove(java.lang.Object key)

Specified by:

remove in interface java.util.Map<K,V>

Overrides:

remove in class java.util.AbstractMap<K,V>

commit

public void commit()

Commits the changes to the original map. Clears the list of removed keys.

isModified

public boolean isModified()

Returns true if the internal map was modified.

toDebugString

public java.lang.String toDebugString()

Returns a debug string.

clear

public void clear()

Specified by:

clear in interface java.util.Map<K,V>

Overrides:

clear in class java.util.AbstractMap<K,V>

getOriginal

public java.util.Map<K,V> getOriginal()

Returns the original wrapped Map.

setOriginal

public void setOriginal(java.util.Map<K,V> original)

Sets the original values of this delta map.

getChanged

public java.util.Map<K,V> getChanged()

Returns a Map of the entries changed, not including those removed.

getRemoved

public java.util.Set<K> getRemoved()

Returns the entries removed, including entries excluded by the constructor.