[rules-users] Multiple Object Referencing problem

[David Sinclair]

This has nothing to do with Drools. It looks like you are giving Writer bad
input perhaps??

Exception in thread "main" *java.lang.NullPointerException*

      at java.io.Writer.write(Unknown Source)

      at com.org.RulesTest.main(*RulesTest.java:58*)




2010/6/7 Fnu Mahalakshmi <FMahalakshmi at nyx.com>

>  Hi,
>
>
>
> I am trying out this example from the book :
>
> public class Room {
>
>     private String name
>
>     // getter and setter methods here
>
> }
>
> public classs Sprinkler {
>
>     private Room room;
>
>     private boolean on;
>
>     // getter and setter methods here
>
> }
>
> public class Fire {
>
>     private Room room;
>
>     // getter and setter methods here
>
> }
>
>
>
> I load 2 input files: 1. with data of fire and Room { f1, r1;f2, r2}
>
>                            2. with data of sprinkler and Room { “ “, r1; “
> “ , r2}
>
>
>
> I am writing rule “ if fire exists in room start sprinkler” { so if f1 and
> r1 in this case: I should get s1, r1 }
>
> when
>
>     Fire($room : room)
>
>     $sprinkler : Sprinkler( room == $room, modified == false )
>
> Then
>
>     $sprinkler.setmodified(true);
>
>     modify( $sprinkler ) { setSprinkle( “s1” ) };
>
> end
>
>
>
> But this gives me error:
>
> Exception in thread "main" *java.lang.NullPointerException*
>
>       at java.io.Writer.write(Unknown Source)
>
>       at com.org.RulesTest.main(*RulesTest.java:58*)
>
>
>
> From what I observed this rule is not getting fired at all.
>
> I want this rule to be fired on the data in my second input file.
>
> The rules for my first input file get executed properly.
>
>
>
> Can any1 tell me where I am going wrong??
>
> Is there any way in which we can use the modified data { after rules are
> fired on the first input data and it is  modified}to fire another set of
> rules on the same input depending on the next input file???
>
>
>
> Thank you.
>
>
>
> -M
>
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