Details
-
Bug
-
Status: Closed
-
Major
-
Resolution: Fixed
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Jena 3.4.0
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None
Description
As reported by Chris Dollin on users mailing list:
I was experimenting with the query builder and hit a problem
when I was attempting to construct an Expr. This example:
package com.epimorphics.scratch;
import org.apache.jena.arq.querybuilder.ConstructBuilder;
import org.apache.jena.sparql.expr.E_GreaterThan;
import org.apache.jena.sparql.expr.Expr;
import org.apache.jena.sparql.expr.ExprVar;
import org.apache.jena.sparql.expr.nodevalue.NodeValueInteger;
import org.junit.Test;
public class Example {
@Test public void tryBuilding()
{ ConstructBuilder cb = new ConstructBuilder(); Expr x = new NodeValueInteger(1); Expr y = new ExprVar("y"); Expr e = new E_GreaterThan(x, y); cb.addFilter(e); System.err.println(cb.buildString()); }}
when run fails with a null pointer exception:
java.lang.NullPointerException
at org.apache.jena.arq.querybuilder.rewriters.
AbstractRewriter.changeNode(AbstractRewriter.java:126)
at org.apache.jena.arq.querybuilder.rewriters.NodeValueRewriter.visit(
NodeValueRewriter.java:64)
at org.apache.jena.sparql.expr.nodevalue.NodeValueInteger.
visit(NodeValueInteger.java:78)
at org.apache.jena.arq.querybuilder.rewriters.ExprRewriter.visit(
ExprRewriter.java:127)
at org.apache.jena.sparql.expr.NodeValue.visit(NodeValue.java:1205)
at org.apache.jena.arq.querybuilder.rewriters.ExprRewriter.visit(
ExprRewriter.java:65)
at org.apache.jena.sparql.expr.ExprFunction2.visit(
ExprFunction2.java:109)
at org.apache.jena.arq.querybuilder.rewriters.ElementRewriter.visit(
ElementRewriter.java:70)
at org.apache.jena.sparql.syntax.ElementFilter.visit(
ElementFilter.java:35)
at org.apache.jena.arq.querybuilder.rewriters.ElementRewriter.visit(
ElementRewriter.java:141)
at org.apache.jena.sparql.syntax.ElementGroup.visit(
ElementGroup.java:120)
at org.apache.jena.arq.querybuilder.handlers.WhereHandler.addAll(
WhereHandler.java:81)
at org.apache.jena.arq.querybuilder.handlers.HandlerBlock.addAll(
HandlerBlock.java:218)
at org.apache.jena.arq.querybuilder.handlers.HandlerBlock.addAll(
HandlerBlock.java:245)
at org.apache.jena.arq.querybuilder.AbstractQueryBuilder.build(
AbstractQueryBuilder.java:555)
at org.apache.jena.arq.querybuilder.AbstractQueryBuilder.buildString(
AbstractQueryBuilder.java:522)
at com.epimorphics.scratch.Example.tryBuilding(Example.java:20)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(
NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(
DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(
FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(
ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(
FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.
evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(
BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(
BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(
JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.
startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(
JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(
JUnitStarter.java:70)
Replacing the addFilter line with
cb.addFilter("1 > ?y");
does not fail, terminating with the expected print-out
of a construct query
CONSTRUCT
{
}
WHERE
I tried poking around with the debugger but couldn't see anyhting
obvious. However, /sometimes/ stepping through the code
results in it working and sometimes not, presumably depending
on exactly when I give up through-stepping.
Am I doing anything obviously wrong (like misunderstanding
how to use the Expr functionality) or should I file a JIRA?
This is Jena 3.4.0.
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