com.hp.hpl.jena.sparql.expr.aggregate

Class AggNull

java.lang.Object

com.hp.hpl.jena.sparql.expr.aggregate.AggregatorBase

com.hp.hpl.jena.sparql.expr.aggregate.AggNull

All Implemented Interfaces:

Aggregator

public class AggNull
extends AggregatorBase

The null aggregate (which can't be written in SPARQL) calculates nothering but does help remember the group key

Constructor Summary

Constructors

Constructor and Description
AggNull()

Method Summary

Methods

Modifier and Type	Method and Description
Aggregator	copy(Expr expr)
static Accumulator	createAccNull()
Accumulator	createAccumulator() Create an accumulator for this aggregator
boolean	equals(Object other)
Expr	getExpr() Get the expression - may be null (e.g COUNT(*)) ;
Node	getValueEmpty() Value if there are no elements in any group : return null for no result
int	hashCode()
String	toPrefixString()
String	toString()

Methods inherited from class com.hp.hpl.jena.sparql.expr.aggregate.AggregatorBase

copyTransform, getValue, key

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AggNull

public AggNull()

Method Detail

copy

public Aggregator copy(Expr expr)

toString

public String toString()

Specified by:

toString in class AggregatorBase

toPrefixString

public String toPrefixString()

Specified by:

toPrefixString in interface Aggregator

Specified by:

toPrefixString in class AggregatorBase

createAccumulator

public Accumulator createAccumulator()

Description copied from interface: Aggregator

Create an accumulator for this aggregator

Specified by:

createAccumulator in interface Aggregator

Specified by:

createAccumulator in class AggregatorBase

getValueEmpty

public Node getValueEmpty()

Description copied from interface: Aggregator

Value if there are no elements in any group : return null for no result

Specified by:

getValueEmpty in interface Aggregator

Specified by:

getValueEmpty in class AggregatorBase

getExpr

public Expr getExpr()

Description copied from interface: Aggregator

Get the expression - may be null (e.g COUNT(*)) ;

hashCode

public int hashCode()

Specified by:

hashCode in interface Aggregator

Specified by:

hashCode in class AggregatorBase

equals

public boolean equals(Object other)

Specified by:

equals in interface Aggregator

Specified by:

equals in class AggregatorBase

createAccNull

public static Accumulator createAccNull()