Look closely at your stack trace: it says "Message: Called method
threw an exception." If you called getCause() on the JessException,
it would return a NullPointerException, and if you looked at that
NPE's stack trace, you'd see it was thrown by the getA() method of
your Test class. Here are the relevant lines from your code:
private Integer a = null;
...
public int getA() {
return a;
}
Note that the type of variable "a" is Integer, but getA() is
returning an int. That means that, due to auto-unboxing, the Java
compiler is going to emit code as if you had written something like
public int getA() {
return a.intValue();
}
and since "a" is null, this line throws a NullPointerException. It's
not Jess's fault if your getter methods throw NPEs when called!
On Aug 3, 2007, at 2:51 PM, Skeptic 2000 wrote:
Hi and thanks a lot for helping, the details are here :
That's the ShadowFact :
public class Test {
private Integer a = null;
private Integer b = 4;
public Test() {
}
public int getA() {
return a;
}
public int getB() {
return b;
}
}
That's the .CLP file :
(defclass Test xxx.yyy.zzz.Test)
(defrule testrule
(Test (a ?a) (b ?b))
=>
(printout t "testrule ok")
)
That's the java code :
void functionX() {
...
jessEngine.add(new Test());
...
}
That's the exception :
Jess reported an error in routine DefinstanceList.updateMultipleSlots.
Message: Called method threw an exception.
at jess.DefinstanceList.getSlotValueFromObject(DefinstanceList.java:
371)
at jess.DefinstanceList.setAllSlotValuesFromObject
(DefinstanceList.java:353)
at jess.DefinstanceList.createNewShadowFact(DefinstanceList.java:332)
at jess.DefinstanceList.definstance(DefinstanceList.java:111)
at jess.Rete.definstance(Rete.java:1903)
at jess.Rete.definstance(Rete.java:1883)
at jess.Rete.add(Rete.java:2023)
...
JFL
> From: [EMAIL PROTECTED]
> Subject: Re: JESS: dealing with shadow facts having null properties
> Date: Fri, 3 Aug 2007 10:48:15 -0400
> To: jess-users@sandia.gov
>
> I can't reproduce anything like this; can you show me a stack trace
> (run jess.Main with -stacktrace to see a full error trace).
>
> On Aug 2, 2007, at 6:12 PM, Skeptic 2000 wrote:
>
> >
> > When I add a shadow fact with a property having a null value, I
get
> > an exception (in updateMultiSlot IRRC).
> >
> > JFL
> >
> > > From: [EMAIL PROTECTED]
> > > Subject: Re: JESS: dealing with shadow facts having null
properties
> > > Date: Thu, 2 Aug 2007 15:57:55 -0400
> > > To: jess-users@sandia.gov
> > >
> > > Jess has been able to handle null properties for a long time;
6.1p8
> > > can handle them, as can the current versions. What problem
are you
> > > having, exactly?
> > >
> > > On Aug 2, 2007, at 2:19 PM, Skeptic 2000 wrote:
> > >
> > > >
> > > > Hi,
> > > >
> > > > I need to add in the working memory some shadow facts with
> > > > properties whose values are null. Currently, my workaround
is to
> > > > use a "NullObject" to prevent Jess from crashing upon
finding a
> > > > null value.
> > > >
> > > > Is it the recommended way to do it ?
> > > >
> > > > JFL
> > > >
> > > > Soyez parmi les premiers à essayer Windows Live Mail.
> > >
> > > ---------------------------------------------------------
> > > Ernest Friedman-Hill
> > > Advanced Software Research Phone: (925) 294-2154
> > > Sandia National Labs FAX: (925) 294-2234
> > > PO Box 969, MS 9012 [EMAIL PROTECTED]
> > > Livermore, CA 94550 http://www.jessrules.com
> > >
> > >
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> > > in the BODY of a message to [EMAIL PROTECTED], NOT to the
list
> > > (use your own address!) List problems? Notify owner-jess-
> > [EMAIL PROTECTED]
> > >
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> > >
> >
> >
> > Soyez parmi les premiers à essayer Windows Live Mail.
>
> ---------------------------------------------------------
> Ernest Friedman-Hill
> Advanced Software Research Phone: (925) 294-2154
> Sandia National Labs FAX: (925) 294-2234
> PO Box 969, MS 9012 [EMAIL PROTECTED]
> Livermore, CA 94550 http://www.jessrules.com
>
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[EMAIL PROTECTED]'
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Soyez parmi les premiers à essayer Windows Live Mail.
---------------------------------------------------------
Ernest Friedman-Hill
Advanced Software Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://www.jessrules.com
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