Package org.eclipse.rdf4j.query

Interface QueryResultHandler

All Known Subinterfaces:

BooleanQueryResultHandler, BooleanQueryResultWriter, QueryResultWriter, TupleQueryResultHandler, TupleQueryResultWriter

All Known Implementing Classes:

AbstractQueryResultWriter, AbstractTupleQueryResultHandler, BackgroundTupleResult, BinaryQueryResultWriter, BooleanTextWriter, ConsoleQueryResultWriter, DAWGTestResultSetWriter, QueryResultCollector, SPARQLBooleanJSONWriter, SPARQLBooleanXMLWriter, SPARQLResultsCSVWriter, SPARQLResultsJSONWriter, SPARQLResultsTSVWriter, SPARQLResultsXMLWriter, SPARQLStarResultsJSONWriter, SPARQLStarResultsTSVWriter, SPARQLStarResultsXMLWriter, TupleQueryResultBuilder

public interface QueryResultHandler

The super class of all handlers for processing query results.

This interface contains methods for optionally processing both boolean and tuple results sets simultaneously, but there are no guarantees that an implementation will be able to process these values together. If a method is not supported then an UnsupportedOperationException will be thrown to indicate this failure. This failure may be prevented by checking for whether the class implements BooleanQueryResultHandler or TupleQueryResultHandler, for boolean and tuple results support respectively.

If both boolean and tuple results are supported but they are not able to to be processed simultaneously, then a checked exception, either BooleanQueryResultHandlerException or TupleQueryResultHandlerException, will be thrown to indicate this failure when the relevant methods are called.

Author:

Peter Ansell

Method Summary

Modifier and Type	Method	Description
void	endQueryResult()	Indicates the end of a sequence of solutions.
void	handleBoolean(boolean value)	Handles the specified boolean value.
void	handleLinks(List<String> linkUrls)	Handles the links elements which are present in SPARQL Results JSON and SPARQL Results XML documents in the header.
void	handleSolution(BindingSet bindingSet)	Handles a solution.
void	startQueryResult(List<String> bindingNames)	Indicates the start of a sequence of Solutions.

Method Details

handleBoolean

void handleBoolean(boolean value)
            throws QueryResultHandlerException

Handles the specified boolean value.

Parameters:

value - The boolean value to handle.

Throws:

QueryResultHandlerException - If there was an error during the handling of this value. This exception may be thrown if the startQueryResult(List), handleSolution(BindingSet) or endQueryResult() methods were called before this method was called, and the handler cannot process both boolean and tuple results simultaneously.

UnsupportedOperationException - If this method is not supported

handleLinks

void handleLinks(List<String> linkUrls)
          throws QueryResultHandlerException

Handles the links elements which are present in SPARQL Results JSON and SPARQL Results XML documents in the header.

NOTE: If the format does not support links, it must silently ignore a call to this method.

An accumulating handler should accumulate these links.

Parameters:

linkUrls - The URLs of the links to handle.

Throws:

QueryResultHandlerException - If there was an error handling the set of link URLs. This error is not thrown in cases where links are not supported.

See Also:

• "link"

startQueryResult

void startQueryResult(List<String> bindingNames)
               throws TupleQueryResultHandlerException

Indicates the start of a sequence of Solutions. The supplied bindingNames are an indication of the values that are in the Solutions. For example, a SPARQL query like select ?X ?Y where { ?X ?P ?Y } will have binding names X and Y.

Parameters:

bindingNames - An ordered set of binding names.

Throws:

TupleQueryResultHandlerException - If there was an error during the starting of the query result handler. This exception may be thrown if the handleBoolean(boolean) method was called before this method and the handler cannot process both boolean and tuple results simultaneously.

UnsupportedOperationException - If this method is not supported

IllegalStateException - If the handleSolution(BindingSet) or endQueryResult() methods were called before this method and the handler cannot process multiple sets of tuple results simultaneously.

endQueryResult

void endQueryResult()
             throws TupleQueryResultHandlerException

Indicates the end of a sequence of solutions.

Throws:

TupleQueryResultHandlerException - If there was an error during the ending of the query result handler. This exception may be thrown if the handleBoolean(boolean) method was called before this method and the handler cannot process both boolean and tuple results simultaneously.

UnsupportedOperationException - If this method is not supported

IllegalStateException - If the endQueryResult() was previously called for this handler or startQueryResult(List) was NOT called before this method.

handleSolution

void handleSolution(BindingSet bindingSet)
             throws TupleQueryResultHandlerException

Handles a solution.

Parameters:

bindingSet - A single set of tuple results, with binding names bound to values. Each of the binding names in the solution must have previously been registered with the startQueryResult(List) method.

Throws:

TupleQueryResultHandlerException - If there was an error during the handling of the query solution. This exception may be thrown if the handleBoolean(boolean) method was called before this method and the handler cannot process both boolean and tuple results simultaneously.

UnsupportedOperationException - If this method is not supported

IllegalStateException - If the endQueryResult() method was called before this method or startQueryResult(List) was NOT called before this method.