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

java.lang.Object
  extended by com.hp.hpl.jena.sparql.expr.aggregate.AggregatorBase
      extended by 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
AggNull()
           
 
Method Summary
 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(*)) ;
 com.hp.hpl.jena.graph.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 com.hp.hpl.jena.graph.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()


Licenced under the Apache License, Version 2.0