RE: [drools-user] Strange Exception

[Leo van den Berg]

List is an Interface and not a concrete class, You should use a "real
class" such as LinkedList and instantiate it first --> List list = new
LinkedList();




-----Mensaje original-----
De: Charles Lee [mailto:[EMAIL PROTECTED] 
Enviado el: miércoles, 26 de abril de 2006 15:33
Para: user@drools.codehaus.org
Asunto: [drools-user] Strange Exception

Hi,

I have written a simple rule:

#list any import classes here.
import test.Person

rule "check pete"
        when
                fet : Person( name == "pete");
        then
                System.out.println("fet name " + fet.getName());
end


When I run this it passes;

But If I run the same rule but in the RHS I add the person to the list,

like so:

#list any import classes here.
import test.Person


#declare any global variables here
global java.util.List list


rule "check pete"
        when
                fet : Person( name == "pete");
        then
                list.add( fet );                
end

I am getting the following error

org.drools.spi.ConsequenceException: java.lang.NullPointerException
        at org.drools.common.Agenda.fireActivation(Agenda.java:316)
        at org.drools.common.Agenda.fireNextItem(Agenda.java:290)
        at  
org.drools.reteoo.WorkingMemoryImpl.fireAllRules(WorkingMemoryImpl.java:
253)
        at  
org.drools.reteoo.WorkingMemoryImpl.fireAllRules(WorkingMemoryImpl.java:
266)
        at client.test.RuleBootStrap.runRules(RuleBootStrap.java:51)
        at client.test.RuleTest.testGetEmbo(RuleTest.java:10)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at  
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.jav
a:39)
        at  
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessor
Impl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at junit.framework.TestCase.runTest(TestCase.java:154)
        at junit.framework.TestCase.runBare(TestCase.java:127)
        at junit.framework.TestResult$1.protect(TestResult.java:106)
        at junit.framework.TestResult.runProtected(TestResult.java:124)
        at junit.framework.TestResult.run(TestResult.java:109)
        at junit.framework.TestCase.run(TestCase.java:118)
        at junit.framework.TestSuite.runTest(TestSuite.java:208)
        at junit.framework.TestSuite.run(TestSuite.java:203)
        at  
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTe
stRunner.java:481)
        at  
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRun
ner.java:347)
        at  
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRu
nner.java:197)
Caused by: java.lang.NullPointerException
        at  
uk.ac.ebi.submission.rules.Rule_add_new_gene_symbol_0.consequence(Rule_a
dd_new_gene_symbol_0.java:6)
        at  
uk.ac.ebi.submission.rules.Rule_add_new_gene_symbol_0ConsequenceInvoker.
evaluate(Rule_add_new_gene_symbol_0ConsequenceInvoker.java:21)
        at org.drools.common.Agenda.fireActivation(Agenda.java:313)
        ... 20 more

Any ideas?

Thanks in advance


-- 
Charlie