Java中JESS的输出

Question

I want to send a "fact" to a JESS file within java and get the results back. I basicly batch the JESS file and then send my data (structure in here) into the engine by .add(). I tried to get the JESS results, which should be a string, into a "Value".

Rete engine = new Rete();
engine.batch("file.clp");
Value = AAAnull;
try{
   engine.add(structure)
   AAA = engine.eval("(run)");
   } catch ...

System.out.println(AAA);

The result is always a number, although the result should be a string. I have worked it out in a simple java project and the AAA is returning the string, but here it is not working.

Answer 1

The (run) function returns the number of rules fired; that's the number you're seeing here.

The real results of running your program are the side effects it causes; getting the result in Java depends on what side effects you're expecting. That may mean anything from collecting output printed to the screen , finding newly created facts in working memory , or having your Jess program call Java methods that effect the outside world . Without seeing the contents of file.clp I can't say what you're expecting, but all of these things listed are covered in the Jess manual; the phrases above are links to the appropriate sections. I'm happy to answer any followup questions you might have.