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