[rules-users] NullPointerException in a simple test -- a Drools bug?

[Edson Tirelli]

   Christian,

   Yes, looks like a bug. Can you please open a JIRA for it?

   Thank you,
       Edson


2007/7/27, Christian Spurk <Christian.Spurk at dfki.de>:
>
> Hi all,
>
> I'm trying to migrate my JBoss v3.0.6 rules to the latest v4.0.0
> release. I could already resolve some issues but now I'm already stuck
> for hours with a NullPointerException that I can't get rid of. I broke
> the problem down to a relatively small set of test files that I'd like
> to show you here:
>
>
> /* SimpleTest.java */
> package com.sample;
> // ... imports removed for brevity
> public class SimpleTest {
>    public static final void main(String[] args) throws Exception {
>      PackageBuilder builder = new PackageBuilder();
>      builder.addPackageFromDrl(new InputStreamReader(SimpleTest.class
>          .getResourceAsStream("/rf1.drl")));
>      builder.addPackageFromDrl(new InputStreamReader(SimpleTest.class
>          .getResourceAsStream("/rf2.drl")));
>      RuleBase rb = RuleBaseFactory.newRuleBase();
>      rb.addPackage(builder.getPackage());
>      WorkingMemory wm = rb.newStatefulSession();
>      wm.insert(new Task()); // <-- crashes here
>      wm.fireAllRules();
>    }
> }
>
>
> /* Task.java */
> package com.sample;
> public class Task {
>    private String next = null;
>    public String getNext() {
>      return next;
>    }
>    public void setNext(String next) {
>      this.next = next;
>    }
> }
>
>
> // rf1.drl
> package com.sample
> rule "r0"
>    when
>         Task( next == null ); # <-- change to "x"
>    then
>         System.out.println("r0");
> end
> rule "r1"
>    when
>         Task( next == "1" );
>    then
>         System.out.println("r1");
> end
>
>
> // rf2.drl
> package com.sample
> rule "r2"
>    when
>         Task( next == "2" );
>    then
>         System.out.println("r1");
> end
>
>
> As you can see there are two Drools rule files and two Java classes. If
> I run the SimpleTest class, I get the following exception:
>
> Exception in thread "main" java.lang.NullPointerException
>         at
> org.drools.reteoo.CompositeObjectSinkAdapter$HashKey.equals(
> CompositeObjectSinkAdapter.java:608)
>         at
> org.drools.util.AbstractHashTable$EqualityEquals.equal(
> AbstractHashTable.java:345)
>         at org.drools.util.ObjectHashMap.get(ObjectHashMap.java:86)
>         at
> org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(
> CompositeObjectSinkAdapter.java:295)
>         at org.drools.reteoo.ObjectTypeNode.assertObject(
> ObjectTypeNode.java:168)
>         at org.drools.reteoo.Rete.assertObject(Rete.java:168)
>         at org.drools.reteoo.ReteooRuleBase.assertObject(
> ReteooRuleBase.java:190)
>         at
> org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java
> :70)
>         at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java
> :848)
>         at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java
> :822)
>         at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java
> :623)
>         at com.sample.SimpleTest.main(SimpleTest.java:22)
>
> I've marked the position in the source code at which the run crashes.
> Does anybody have an idea what's wrong here?
>
> Some more strange things relating to this problem:
>   * If I change the 'null' in rf1.drl to '""' (empty string), the
> problem remains.
>   * If I change the 'null' in rf1.drl to '"x"' (or some other non-empty
> string), then the exception is gone.
>   * If I remove any of the two rule files, the exception is gone, too.
>
> Any ideas? Should I file a bug?
>
> Thanks in advance!
>
> Cheers,
> Christian
>
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>
>
>


-- 
  Edson Tirelli
  Software Engineer - JBoss Rules Core Developer
  Office: +55 11 3529-6000
  Mobile: +55 11 9287-5646
  JBoss, a division of Red Hat @ www.jboss.com
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