Jess can be used in many scenarios but you must guard against the consequences, e.g., whatever results from Swing's use of a thread for dealing with dispatched events. A paint() executing asynchronously while some other thread changes the component's (backing) data is dangerous, Jess or no Jess. -W
On Fri, Nov 13, 2009 at 7:38 AM, Patricia Charlton < [email protected]> wrote: > Hi there, > > Thanks for this. Sorry about the lack of details but the error occurred in > a number of places and not consistently with testing. So while it seemed > like a "null pointer" of sorts it didn't seem to be from the JESS code and > seemed to be some protege/owl problem. > > Further testing and reviewing of the log file from Protege shows some > conflict between running JESS from protege and calling JAVA SWING methods. > It might be the way I call these methods but it seems to be a protege/SWING > problem and not JESS itself. When I run my engine via Java methods or from > the JESS command line without protege the problems don't appear (at least > for now). > > I'm guessing that calling SWING methods from JESS via the protege > environment was never intended? > > Kind regards, > Patricia > > > On 12 Nov 2009, at 09:15, Wolfgang Laun wrote: > > Without any information about your facts (shadow or not) and rules only > very general suggestions are possible. > > NPE's may come up when a slot usually holding an object is null and you > call a method. > > Less obvious are cases when a java.lang.Integer (or similar) is null and > the value is used in an arithmetic operation or a comparison; then unboxing > causes the NPE. > > -W > > > On Mon, Nov 9, 2009 at 10:29 AM, Patricia Charlton < > [email protected]> wrote: > >> Hi there, >> >> I'm developing an inference engine using JESS. I am using protege and JESS >> TAB integration and running JESS from the protege environment. >> >> Occasionally I get an error nested exception is: null. It does not happen >> each time I run the application and I have tested each part independently. >> It is also not always with the same inference about a particular concept. >> >> Is there a known problem between the integration environment where for >> example concept pointers may get dropped? >> >> I am currently at a loss as to how to fix this. It maybe a problem with >> protege/jess or jess tab. >> >> (current environment is MAC, Protege 3.4 and Jess 7.1) >> >> Any help or pointers at this stage would be great. >> >> Kind regards, >> Patricia >> >> >> >> -------------------------------------------------------------------- >> To unsubscribe, send the words 'unsubscribe jess-users [email protected]' >> in the BODY of a message to [email protected], NOT to the list >> (use your own address!) List problems? Notify [email protected] >> . >> -------------------------------------------------------------------- >> >> > >
