[rules-users] NullPointerException with Wrapper objects

[Shannon Lal]

I am no expert on drools; however, you might want to retract loanDeduction
from the Working Memory if it is null.  Your first rule determines that it
is null and then you set the value (ld = 0f); however, you should be using
an insert to put this into working memory.  The other alternative is to
retract the loan Deduction  from working memory and add a logic check in the
Nett Salary rule to see if loan Dedcution is null.

I am working on some Drools stuff today if you need some more help on this.

Shannon


On Wed, May 13, 2009 at 1:14 AM, dhai <sdhari at hotmail.com> wrote:

>
> I am facing problems which many have encountered in the past. I searched
> forums but could not get precise answer. The problem is with null values in
> Wrapper objects. See the following code:
>
> rule "Null Check " salience 100
>        when
>                Salary ( ld : loanDeduction==null || < 0f ) // loanDeduction
> is java.lang.Float
>        then
>                log("Load return is null"); //Global function
>                ld = 0f;
> end
>
> rule "Nett Salary" salience 70
>        when
>                Salary ( nett != ( gross – loanDeduction – pf) )
>        then
>                log("Invalid nett salary amount");
> end
>
> You may have idea what I am trying to do. But I get NullPointerException in
> “Nett Salary” rule when I fire the rules having fact with null in the
> loanDeduction attribute. I believe my “Null Check” exception should execute
> first and it does when I put negative value in loadDeduction. What is
> solution in such a case?
> --
> View this message in context:
> http://www.nabble.com/NullPointerException-with-Wrapper-objects-tp23515500p23515500.html
> Sent from the drools - user mailing list archive at Nabble.com.
>
>
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