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From: Jeff Higgins <jeff@invalid.invalid>
Newsgroups: comp.lang.java.gui
Subject: Re: Strange JTable issue in Sun's Java code
Date: Mon, 16 Jan 2012 15:31:55 -0500
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On 01/16/2012 03:19 PM, Jeff Higgins wrote:
> On 01/16/2012 02:48 PM, Jeff Higgins wrote:
>> On 01/16/2012 01:34 PM, Novice wrote:
>>> I'm getting an exception I don't understand when I attempt to delete all
>>> the data in a small Jtable (46 rows, 3 columns).
>>>
>>> Here's the stacktrace; the "rowCount = 45" is a diagnostic I'm writing:
>>> ========================================================================
>>> rowCount = 45
>>> Exception in thread "AWT-EventQueue-0"
>>> java.lang.ArrayIndexOutOfBoundsException: 0
>>> at javax.swing.SizeSequence.removeEntries(SizeSequence.java:383)
>>
>>> ... When I get to line 383 of that method, I get the same "cannot be
>>> resolved to a variable" notation on EVERY variable in that line, even
>>> variable i, which has just been explicitly set to 0.
>>
> The java.lang.ArrayIndexOutOfBoundsException: 0
> would seem to indicate a null reference to the array in question.
Oops! wrong again. Should be an empty array.
> I cannot say which one it might be because:
>> I don't see any line numbers in the code you have provided.
> getSizes() might have initialized sizes to null, or a may be null.
getSizes() might have returned an empty array or a might be empty.
>> I don't see a variable i in the code you have provided.
>>>
>>> Here's the complete code for this method:
>>>
>>> ========================================================================
>>> /**
>>> * Removes a contiguous group of entries
>>> * from this<code>SizeSequence</code>.
>>> * Note that the values of<code>start</code> and
>>> *<code>length</code> must satisfy the following
>>> * conditions:<code>(0<= start< getSizes().length)
>>> * AND (length>= 0)</code>. If these conditions are
>>> * not met, the behavior is unspecified and an exception
>>> * may be thrown.
>>
>> Where are you checking these?
>>
>>> *
>>> * @param start the index of the first entry to be removed
>>> * @param length the number of entries to be removed
>>> */
>>> public void removeEntries(int start, int length) {
>>> int sizes[] = getSizes();
>>
>> I would set a break point just above.
>>
>>> int end = start + length;
>>> int n = a.length - length;
>>> a = new int[n];
>>
>> What is a?
>>
>>> for (int i = 0; i< start; i++) {
>>> a[i] = sizes[i] ;
>>> }
>>> for (int i = start; i< n; i++) {
>>> a[i] = sizes[i+length] ;
>>> }
>>> setSizes(a);
>>> }
>>> ========================================================================
>>
>