Re: Need a few debugging pointers (no pun intended :)

From: Chuck Hill (chil..lobal-village.net)
Date: Tue Aug 24 2004 - 23:31:32 EDT

  • Next message: Guido Neitzer: "Re: Need a few debugging pointers (no pun intended :)"

    That is really a very odd error. I've never seen anything quite like that.
     Congratulations! ;-)

    Some more of the stack trace might help, but I suspect something is wrong
    with your form bindings.

    Chuck

    At 11:00 PM 24/08/2004 -0400, womai..ac.com wrote:
    >>>>
    I'm working my way through Apple's Web Apps book, and have run into my
    first debugging challenge. I'm in Chapter 7, the Component Communication
    exercise.

    I'm getting a java.lang.NullPointerException when I hit the submit button,
    but that's not really the problem. The problem is that I'm trying to
    figure out how to debug this, and it's eluding me. I had no problems with
    the basic stuff, setting breakpoints and stepping through code. But I'm
    not sure what to do with this error.

    I have a function called submitChanges bound to the submit button, and I
    put a breakpoint on the first line, but it's never getting there. The
    stack trace in the console window (I'm using Eclipse 3) looks like this
    (there's more of it but I figured this was enough):

    [2004-08-24 22:33:08 EDT] <WorkerThread0>
    <com.webobjects.appserver._private.WOComponentRequestHandler>: Exception
    occurred while handling request:
    java.lang.NullPointerException
    [2004-08-24 22:33:08 EDT] <WorkerThread0> java.lang.NullPointerException
            at
    com.webobjects.appserver._private.WOForm._enterFormInContext(WOForm.java:58)
            at
    com.webobjects.appserver._private.WOForm.takeValuesFromRequest(WOForm.java:69)

    The source for WOForm.class and WOComponent.class aren't able to be found
    by Eclipse, and I don't know if it's a configuration snafu on my part or if
    we just treat those as magic black boxes.

    So my question is, how do I go about figuring out where my error is? I'll
    gladly RTFM, I just can't find an appropriate FM to R. I have already
    looked at the debugging help in Eclipse but it wasn't detailed enough for
    this situation (or for my state of newbieness, take your pick :).

    thanks,

    janine

    PS thanks to the several people who posted and e-mailed me about how to get
    past the "does not contain a main type" error. Baby steps... ;)
    <<<< 

    --

    Chuck Hill                                 chil..lobal-village.net
Global Village Consulting Inc.             http://www.global-village.net

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