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Re: Strange JTable issue in Sun's Java code

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Jeff Higgins <jeff@invalid.invalid> wrote in
news:jf4v54$hd0$1@dont-email.me: 

> On 01/17/2012 05:21 PM, Novice wrote:
>> Jeff Higgins<jeff@invalid.invalid>  wrote in
>> news:jf3amd$1rr$1@dont-email.me:
>>
>>> 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.
>>>
>> Since Java 7 didn't change anything except the line number (the
>> failing line number is 400 in Java 7), I've reverted to running Java
>> 6.18. 
>>>>
>>>>       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?
>>>
>> I've looked around and I'm not finding any such settings. Can you
>> please be specific on which menu I should check and which specific
>> settings I'd have had to mess with? (I don't think I've EVER messed
>> with the debug settings but I might as well look, just in case I did
>> at some point and forgot. Or a new version of Eclipse had unexpected
>> values for some settings.)
> 
>  From the main menu:
> Project>Properties>Java Compiler>Classfile Generation
> 
When I go to the Java Compiler page, I see that everything below Enable 
Project Specific Settings is grayed out. "Use default compliance 
settings" is grayed out too but checked. "Generated classfile compliance 
is likewise grayed out but set to 1.6." I assume that is all as it should 
be; correct me if I'm wrong. 
>>
>>>>           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);
>>>>       }
>>>>
>> When I used your SSCCE, it crashed at line 44 (a = new int[n];) which
>> is just above that point. I'm not sure what the significance of that
>> is though.
> 
> Then you must spend some more time pondering it.
> 
> I'm really not quite sure what your SSCCE is trying to do.
> 
> I wrapped your method removeEntries() verbatim into a test class and 
> provided a int[]getSizes() and an int[]a at class scope - because that
> where they looked to be in relation to your removeEntries method. I 
> placed a call to your removeEntries method inside a try block inside
> an executable main method.
> 
> The intent was to provide you a free playground to experiment with the
> values of the variables - only you know what these values should be.
> 
> My SSCCE is currently trying desperately to break out of my scratch
> project. 
> 
>>
>> For what it's worth, I created my own SSCCE which is somewhat longer
>> than yours but more closely parallels what my problem code is
>> doing.It works fine though. It doesn't crash and I'm not getting any
>> of the "cannot be resolved to a variable" nonsense when I try to
>> debug. I put my SSCCE (and yours) in the same project as the one that
>> is blowing up so they must be using the same settings/compiler/etc.
>>
>>>>
>>>> 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.
>>>
>> Can you flesh that out a bit. I have used raw javac a long time ago
>> before I got my first proper editor but I'm not sure what that and
>> jdb will prove here. Are we just trying to establish whether Eclipse
>> and it's compiler are the culprits?
> 
> Yep.
> 
Another IDE would do that too. It might be easier to just download one of 
those, just to try this one program, then delete it again once we've 
figured out this problem.
>>
>>>>
>>>> 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?
>>
>> Your SSCCE has VERY different behavior than mine.
> 
> I am not VERY surprised.
> 
>>
>> Yours actually has values for all of the variables until well into
>> the method. 'start' and 'length' begin as 0 and 3 respectively.
>> getSizes() initially contains [1, 2, 3, 4, 5]. 'getSizes.length' is
>> 5. 'a' is empty. After "int[] sizes = getSize();", 'sizes' contains
>> [1,2,3,4,5]. 'a.length' is 0. 'length' remains 3. 'n' is -3. (0-3).
>> Not surprisingly, Java doesn't like the line "a = int[n]" when n is
>> -3 and this causes the exception just before we get to the first
>> loop. 
>>
>> I've just tried my code again but it's still doing the same nonsense
>> as before. 'getSizes()' actually returns a very reasonable array but
>> after assigning it to 'sizes', I get the "cannot be resolved to a
>> variable" message again. 'start' and 'length' have the same issues on
>> entry to the method. And so it goes until the first iteration of the
>> first loop when it crashes again on the
>> ArrayIndexOutOfBoundsException because the index is 0.
>>
>> I can't figure out if "cannot be resolved to a variable" proves that
>> the debugger is messed up or if it is only masking the underlying
>> error. Maybe something that should be in scope isn't for some
>> reason?? 
>>
>>> One question. Why arrays here, instead of ArrayLists? The answer
>>> would probably be obvious knowing the rest of your code.
>>
>> I don't honestly know. My table model actually consists of a Vector
>> of rows, not an array or a Vector of Vectors. The rows being stored
>> in the Vector have their own custom class that consists of three
>> String fields, one for each of the columns of the JTable. The list of
>> column names to be used in the header is an array but that's just
>> about the only one in the entire program, aside from some local ones
>> used to determine the widest values in each column.
> 
> You are trolling now.
> 
Typically, trolling means saying stuff you don't believe just to get a 
rise out of someone. Maybe you have something different in mind? 
Seriously, I am not making anything up here. The things I'm describing 
ARE happening as I've described.
>>
>> getSizes() is getting an array of 45 entries and that surely
>> corresponds to the number of rows in the table. From looking at
>> getSizes(), it seems as if it might be keeping track of sizes of
>> cells or something like that. 
>>
>>
>> One strange thing jumped out at me when I was debugging my code just
>> now. A System.out.println() that I'd put into another method for a
>> couple of minutes and then deleted is still being executed when I do
>> that method (which sets the column widths of the table). That is
>> REALLY bizarre and suggests that I'm executing a slightly older
>> version of the program. I don't see how that bears on exception I'm
>> getting but it may point to the solution anyway: if I actually
>> executed the code I want to execute, maybe the exception wouldn't be
>> happening. Why would the debugger execute a different version of the
>> code than it is displaying?? 
>>
> No rest for the weary.

You've got that right ;-) 
> 
> 





-- 
Novice

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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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