This is a bug. The problem is that new NodeValueInteger(1); does not set the Node value that the rewriter is trying to rewrite and thus the null pointer exception.
I will get a fix out shortly. Claude On Fri, Nov 17, 2017 at 4:14 PM, Chris Dollin <[email protected]> wrote: > Hi, > > 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 > { FILTER ( 1 > ?y )} > > 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. > > Chris > > > > > -- > "What I don't understand is this ..." Trevor Chaplin, /The Beiderbeck > Affair/ > > Epimorphics Ltd, http://www.epimorphics.com > Registered address: Court Lodge, 105 High Street, Portishead, Bristol BS20 > 6PT > Epimorphics Ltd. is a limited company registered in England (number > 7016688) > -- I like: Like Like - The likeliest place on the web <http://like-like.xenei.com> LinkedIn: http://www.linkedin.com/in/claudewarren
