net.sf.ehcache.search
Class NullResults

java.lang.Object
  net.sf.ehcache.search.NullResults

All Implemented Interfaces:

Results

public class NullResults
extends Object
implements Results

An empty result instance

Author:

teck

Field Summary

static NullResults

INSTANCE A global instance that can be freely shared with the world since this type has no state

Constructor Summary

NullResults()

Method Summary

List<Result>	all() Retrieve all of the cache results in one shot.
void	discard() Discard this query result.
boolean	hasAggregators() Whether the results contains aggregates
boolean	hasAttributes() Whether the Results have cache attributes included.
boolean	hasKeys() Whether the Results have cache keys included.
boolean	hasValues() Whether the Results have cache values included.
List<Result>	range(int start, int count) Retrieve a subset of the cache results.
int	size() Results size

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final NullResults INSTANCE

A global instance that can be freely shared with the world since this type has no state

Constructor Detail

NullResults

public NullResults()

Method Detail

discard

public void discard()

Discard this query result. This call is not mandatory but is recommended after the caller is done with results. It can allow the cache, which may be distributed, to immediately free any resources associated with this result.

Multiple calls are ignored. Attempting to read results from this instance after this method has been called will produce SearchException

Specified by:

discard in interface Results

all

public List<Result> all()
                 throws SearchException

Retrieve all of the cache results in one shot. For large result sets this might consume large amount of memory

Specified by:

all in interface Results

Returns:

a List of all the matching cache entries

Throws:

SearchException

range

public List<Result> range(int start,
                          int count)
                   throws SearchException,
                          IndexOutOfBoundsException

Retrieve a subset of the cache results. This method is useful when showing "paged" results in a user interface or simply to keep memory overhead fixed

Specified by:

range in interface Results

Parameters:

start - starting index to access

count - the number of results to return

Returns:

a List of the given size. This list will be smaller than the requested size if no more results are available. If there are no more results an empty list will be returned.

Throws:

SearchException

IndexOutOfBoundsException

size

public int size()

Results size

Specified by:

size in interface Results

Returns:

number of results present

hasKeys

public boolean hasKeys()

Whether the Results have cache keys included. If so these can be extracted from the Result object.

Specified by:

hasKeys in interface Results

Returns:

true if keys are included

hasValues

public boolean hasValues()

Whether the Results have cache values included. If so these can be extracted from the Result object.

Specified by:

hasValues in interface Results

Returns:

true if values are included

hasAttributes

public boolean hasAttributes()

Whether the Results have cache attributes included. If so these can be extracted from the Result object.

Specified by:

hasAttributes in interface Results

Returns:

true if attributes are included

hasAggregators

public boolean hasAggregators()

Whether the results contains aggregates

Specified by:

hasAggregators in interface Results

Returns:

true if this is an aggregate