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Groups > comp.lang.java.gui > #4950

Re: Strange JTable issue in Sun's Java code

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On 01/16/2012 08:48 PM, Novice wrote:

>
> I've just stepped through the whole removeEntries() method until it
> crashed.

OK, your program crashes inside the removeEntries method - just as the 
stack trace indicated.

I should mention that I downloaded a Java 1.7 JDK and JRE and I'm
> using _that_ version now. The code for this method looks the same but I
> might be missing a subtle difference. Here's the code, along with what I
> saw as I stepped through it:

One way to decide on an update - I'm using Java 6.

>
>      public void removeEntries(int start, int length) {
> //Before executing the following line, start and length both show "cannot
> //be resolved to a variable". When I tried setting them as expressions in
> //the expressions monitor, I got "<error(s)_during_the_evaluation>" for
> //both variables

Have you disabled debug information in your project build settings?

>          int sizes[] = getSizes();
> //getSizes() returns an int array of 45 items; each item has a value of
> //21
> //when I inspect or inspect 'sizes' (without the brackets), I get "sizes
> //cannot be resolved to a variable. It's not clear if the assignment has
> //worked!
> //Before this next line, 'start' and 'length' are still "cannot be
> //resolved to a variable."
>          int end = start + length;
> //After the assignment, 'end' "cannot be resolved to a variable"
> //Before this next line, 'a' is an int array of 45 diverse integers and
> //'a.length is 45. 'length' "cannot be resolved to a variable"
>          int n = a.length - length;
> //After the preceding statement is executed, 'n' "cannot be resolved to a
> //variable"
>          a = new int[n];
> //After the preceding statement is executed, 'a' has a value of "[]" (!!)
>          for (int i = 0; i<  start; i++) {
> //Before the following line is executed the first time, 'i' should be zero
> //but Eclipse says "i cannot be resolved to a variable". 'sizes[i] cannot
> //be resolved to a variable".
>              a[i] = sizes[i] ;
> //Upon executing the preceding line the first time through the loop, we get
> //the ArrayIndexOutOfBoundsException for an index value of 0

Using the SSCCE that I provided elsethread, I can get your method to 
crash at the above line also. I cannot remember with what combinations 
of values.

>          }
>          for (int i = start; i<  n; i++) {
>              a[i] = sizes[i+length] ;
>          }
>          setSizes(a);
>      }
>
>
> This seems REALLY messed up to me. I don't understand why all these
> variables "cannot be resolved to a variable". If they really don't have
> values, why doesn't it crash long before we get to the line where we get
> the exception? But if the variables do have values, why can't Eclipse show
> them to me?
>
> Since a newer JDK/JRE didn't resolve the problem and it happens
> consistently, I'm leaning toward Eclipse as being the problem here. I can't
> think of anything inappropriate that I'm doing in my code and I have to
> believe that the Java team tests these methods pretty thoroughly before
> putting them in a JDK.

You could try another IDE, but that seems drastic.
Another option, you could employ javac and jdb outside the IDE.

>
> Am I thinking along the right lines here? If so, what do I do next? I'd
> like my program to work without getting this apparently inappropriate
> exception but I'm not sure how to accomplish that....

I'd take a deep breath, relax, become intimate with my debugger, and enjoy.
Really, try compiling and running the SSCCE I provided - do you get the 
variable not resolved?
One question. Why arrays here, instead of ArrayLists? The answer would 
probably be obvious knowing the rest of your code.

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Thread

Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-16 18:34 +0000
  Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-16 14:48 -0500
    Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-16 14:55 -0500
    Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-16 15:19 -0500
      Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-16 15:31 -0500
        Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-16 17:57 -0500
    Re: Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-17 01:48 +0000
      Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 03:22 -0500
        Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 03:29 -0500
        Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 03:49 -0500
        Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 03:55 -0500
        Re: Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-17 22:21 +0000
          Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 18:18 -0500
            Re: Strange JTable issue in Sun's Java code Jeff Higgins <jeff@invalid.invalid> - 2012-01-17 20:56 -0500
              Re: Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-18 05:24 +0000
                Re: Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-18 17:40 +0000
            Re: Strange JTable issue in Sun's Java code Novice <novice@example..com> - 2012-01-18 05:37 +0000
  Re: Strange JTable issue in Sun's Java code Christian Kaufhold <chka@ucuri.chka.de> - 2012-01-19 21:00 +0100

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