com.tangosol.util
Class InvocableMapHelper.SimpleEntry

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.InvocableMapHelper.SimpleEntry

All Implemented Interfaces:

InvocableMap.Entry, QueryMap.Entry, Map.Entry

Enclosing class:

InvocableMapHelper

public static class InvocableMapHelper.SimpleEntry
extends Base
implements InvocableMap.Entry

Simple implementation of the InvocableMap.Entry interface. This assumes that the underlying Map content does not change while a reference to the SimpleEntry is alive and may cache the entry's value to avoid an extra map lookup.

Field Summary

protected Map

m_map The map.

Constructor Summary

InvocableMapHelper.SimpleEntry(Map map, Object oKey, boolean fReadOnly)
Construct a SimpleEntry for a given map and a key.

InvocableMapHelper.SimpleEntry(Object oKey, Object oValue)
Construct a SimpleEntry for a given key and value.

Method Summary

protected void	checkMutable() Verify that this SimpleEntry is mutable.
boolean	equals(Object o) Compare this SimpleEntry with another object for equality.
Object	extract(ValueExtractor extractor) Extract a value out of the Entry's value.
Object	getKey() Return the key corresponding to this entry.
Object	getValue() Return the value corresponding to this entry.
int	hashCode() Return a hash code value for the SimpleEntry object.
boolean	isPresent() Determine if this Entry exists in the Map.
void	remove(boolean fSynthetic) Remove this Entry from the Map if it is present in the Map.
Object	setValue(Object oValue) Store the value corresponding to this entry.
void	setValue(Object oValue, boolean fSynthetic) Store the value corresponding to this entry.
String	toString() Provide a human-readable representation of the SimpleEntry object.
void	update(ValueUpdater updater, Object oValue) Update the Entry's value.

Field Detail

m_map

protected Map m_map

The map.

Constructor Detail

InvocableMapHelper.SimpleEntry

public InvocableMapHelper.SimpleEntry(Map map,
                                      Object oKey,
                                      boolean fReadOnly)

Construct a SimpleEntry for a given map and a key.

Parameters:

map - the parent Map for this entry

oKey - the entry's key

fReadOnly - if true, the entry will be marked as read-only, preventing the setValue() and remove() methods from modifying the underlying map's content

InvocableMapHelper.SimpleEntry

public InvocableMapHelper.SimpleEntry(Object oKey,
                                      Object oValue)

Construct a SimpleEntry for a given key and value. The entry will be marked as read-only.

Parameters:

oKey - the entry's key

oValue - the entry's value

Method Detail

getKey

public Object getKey()

Return the key corresponding to this entry. The resultant key does not necessarily exist within the containing Map, which is to say that InvocableMap.this.containsKey(getKey) could return false. To test for the presence of this key within the Map, use InvocableMap.Entry.isPresent(), and to create the entry for the key, use InvocableMap.Entry.setValue(java.lang.Object).

Specified by:

getKey in interface InvocableMap.Entry

Specified by:

getKey in interface Map.Entry

Returns:

the key corresponding to this entry; may be null if the underlying Map supports null keys

getValue

public Object getValue()

Return the value corresponding to this entry. If the entry does not exist, then the value will be null. To differentiate between a null value and a non-existent entry, use InvocableMap.Entry.isPresent().

Note: any modifications to the value retrieved using this method are not guaranteed to persist unless followed by a InvocableMap.Entry.setValue(java.lang.Object) or InvocableMap.Entry.update(com.tangosol.util.ValueUpdater, java.lang.Object) call.

Specified by:

getValue in interface InvocableMap.Entry

Specified by:

getValue in interface Map.Entry

Returns:

the value corresponding to this entry; may be null if the value is null or if the Entry does not exist in the Map

setValue

public Object setValue(Object oValue)

Store the value corresponding to this entry. If the entry does not exist, then the entry will be created by invoking this method, even with a null value (assuming the Map supports null values).

Specified by:

setValue in interface InvocableMap.Entry

Specified by:

setValue in interface Map.Entry

Parameters:

oValue - the new value for this Entry

Returns:

the previous value of this Entry, or null if the Entry did not exist

setValue

public void setValue(Object oValue,
                     boolean fSynthetic)

Store the value corresponding to this entry. If the entry does not exist, then the entry will be created by invoking this method, even with a null value (assuming the Map supports null values).

Unlike the other form of setValue, this form does not return the previous value, and as a result may be significantly less expensive (in terms of cost of execution) for certain Map implementations.

Specified by:

setValue in interface InvocableMap.Entry

Parameters:

oValue - the new value for this Entry

fSynthetic - pass true only if the insertion into or modification of the Map should be treated as a synthetic event

extract

public Object extract(ValueExtractor extractor)

Extract a value out of the Entry's value. Calling this method is semantically equivalent to extractor.extract(entry.getValue()), but this method may be significantly less expensive. For example, the resultant value may be obtained from a forward index, avoiding a potential object de-serialization.

Specified by:

extract in interface QueryMap.Entry

Parameters:

extractor - a ValueExtractor to apply to the Entry's value

Returns:

the extracted value

update

public void update(ValueUpdater updater,
                   Object oValue)

Update the Entry's value. Calling this method is semantically equivalent to:

   Object oTarget = entry.getValue();
   updater.update(oTarget, oValue);
   entry.setValue(oTarget, false);
 

The benefit of using this method is that it may allow the Entry implementation to significantly optimize the operation, such as for purposes of delta updates and backup maintenance.

Specified by:

update in interface InvocableMap.Entry

Parameters:

updater - a ValueUpdater used to modify the Entry's value

isPresent

public boolean isPresent()

Determine if this Entry exists in the Map. If the Entry is not present, it can be created by calling InvocableMap.Entry.setValue(java.lang.Object) or InvocableMap.Entry.setValue(java.lang.Object). If the Entry is present, it can be destroyed by calling InvocableMap.Entry.remove(boolean).

Specified by:

isPresent in interface InvocableMap.Entry

Returns:

true iff this Entry is existent in the containing Map

remove

public void remove(boolean fSynthetic)

Remove this Entry from the Map if it is present in the Map.

This method supports both the operation corresponding to Map.remove(java.lang.Object) as well as synthetic operations such as eviction. If the containing Map does not differentiate between the two, then this method will always be identical to InvocableMap.this.remove(getKey()).

Specified by:

remove in interface InvocableMap.Entry

Parameters:

fSynthetic - pass true only if the removal from the Map should be treated as a synthetic event

equals

public boolean equals(Object o)

Compare this SimpleEntry with another object for equality.

Specified by:

equals in interface Map.Entry

Parameters:

o - an object reference or null

Returns:

true iff the passed object reference is a SimpleEntry object with the same key

hashCode

public int hashCode()

Return a hash code value for the SimpleEntry object.

Specified by:

hashCode in interface Map.Entry

toString

public String toString()

Provide a human-readable representation of the SimpleEntry object.

Returns:

a String representation of this SimpleEntry object

checkMutable

protected void checkMutable()

Verify that this SimpleEntry is mutable.