[jboss-jira] [JBoss JIRA] Updated: (JBRULES-1045) Predicate Null Pointer exception when using Java 5 Enum
[ http://jira.jboss.com/jira/browse/JBRULES-1045?page=all ]
christopher barham updated JBRULES-1045:
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With guidance from Rikkola on IRC, amending the Enum to have a getter returning itself
enabled it to work:
public enum Message {GOODBYE, HELLO; private Message type; public Message getType() {
return this; } }
then the drl rule became:
m : Message( type == Message.HELLO )
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@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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