net.fortytwo.sesametools
Class ValueComparator

java.lang.Object
  net.fortytwo.sesametools.ValueComparator

All Implemented Interfaces:

Comparator<org.openrdf.model.Value>

public class ValueComparator
extends Object
implements Comparator<org.openrdf.model.Value>

Implements a Comparator for OpenRDF Value objects where:

the order for Values is: * Blank Node's * URI's * Literals

with null Values sorted before others

Author:

Peter Ansell p_ansell@yahoo.com

Field Summary

static int	AFTER
static int	BEFORE
static int	EQUALS

Constructor Summary

ValueComparator()

Method Summary

int

compare(org.openrdf.model.Value first, org.openrdf.model.Value second) Sorts in the order nulls>BNodes>URIs>Literals This is due to the fact that nulls are only applicable to contexts, and according to the OpenRDF documentation, the type of the null cannot be sufficiently distinguished from any other Value to make an intelligent comparison to other Values http://www.openrdf.org/doc/sesame2/api/org/openrdf/OpenRDFUtil.html#verifyContextNotNull(org.openrdf.model.Resource...) BNodes are sorted according to the lexical compare of their identifiers, which provides a way to sort statements with the same BNodes in the same positions, near each other BNode sorting is not specified across sessions

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Field Detail

BEFORE

public static final int BEFORE

See Also:

Constant Field Values

EQUALS

public static final int EQUALS

See Also:

Constant Field Values

AFTER

public static final int AFTER

See Also:

Constant Field Values

Constructor Detail

ValueComparator

public ValueComparator()

Method Detail

compare

public int compare(org.openrdf.model.Value first,
                   org.openrdf.model.Value second)

Sorts in the order nulls>BNodes>URIs>Literals

This is due to the fact that nulls are only applicable to contexts, and according to the OpenRDF documentation, the type of the null cannot be sufficiently distinguished from any other Value to make an intelligent comparison to other Values

http://www.openrdf.org/doc/sesame2/api/org/openrdf/OpenRDFUtil.html#verifyContextNotNull(org.openrdf.model.Resource...)

BNodes are sorted according to the lexical compare of their identifiers, which provides a way to sort statements with the same BNodes in the same positions, near each other

BNode sorting is not specified across sessions

Specified by:

compare in interface Comparator<org.openrdf.model.Value>