[jboss-jira] [JBoss JIRA] Created: (JBRULES-1045) Predicate Null Pointer exception when using Java 5 Enum

[christopher barham (JIRA)]

Predicate Null Pointer exception when using Java 5 Enum
-------------------------------------------------------

                 Key: JBRULES-1045
                 URL: http://jira.jboss.com/jira/browse/JBRULES-1045
             Project: JBoss Rules
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions:  4.0.0.GA
         Environment: Windows XP sp2, Jboss Rules 4.0.0 GA, Sun Java 1.5.0_11 VM, Eclipse 3.3 with JBOss Rules IDE 4.0 
            Reporter: christopher barham
         Assigned To: Mark Proctor


Java 5 enums as column constraint do not work as expected.  Cqauses Null pointer exception in mvel.MVELPredicateExpression.evaluate.

Using modified Eclipse generated  Sample project to demonstrate:

DroolsTest now has an Enum for it's Message:

package com.sample;

import java.io.InputStreamReader;
import java.io.Reader;

import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.WorkingMemory;
import org.drools.compiler.PackageBuilder;
import org.drools.rule.Package;

/**
 * This is a sample file to launch a rule package from a rule source file.
 */
public class DroolsTest {

    public static final void main(String[] args) {
        try {
            RuleBase ruleBase = readRule();
            WorkingMemory workingMemory = ruleBase.newStatefulSession();
            workingMemory.insert(Message.HELLO);
            workingMemory.fireAllRules();
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }

    private static RuleBase readRule() throws Exception {
        // read in the source
        Reader source = new InputStreamReader(DroolsTest.class.getResourceAsStream("/Sample.drl"));
        PackageBuilder builder = new PackageBuilder();
        builder.addPackageFromDrl(source);
        Package pkg = builder.getPackage();
        RuleBase ruleBase = RuleBaseFactory.newRuleBase();
        ruleBase.addPackage(pkg);
        return ruleBase;
    }

    public enum Message {
        GOODBYE, HELLO;
    }

}


The Sample.drl rule is modified to:

package com.sample

import com.sample.DroolsTest.Message;

rule "Hello World"
  when
    m : Message( Message.HELLO )
  then
    System.out.println( m );
end

Stack trace given is:
org.drools.RuntimeDroolsException: Exception executing predicate org.drools.base.mvel.MVELPredicateExpression at 10382a9
	at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:197)
	at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:122)
	at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:20)
	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.DroolsTest.main(DroolsTest.java:21)
Caused by: java.lang.NullPointerException
	at org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:39)
	at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:191)
	... 10 more











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