<Swing Dev> [10] RFR JDK-8191639:NPE from BasicListUI.Actions.getNextPageIndex

[Prasanta Sadhukhan]

Ok. I have added the check for scrollRectToVisible() too.

http://cr.openjdk.java.net/~psadhukhan/8191639/webrev.02/

Regards
Prasanta
On 11/28/2017 1:01 PM, Sergey Bylokhov wrote:
> On 27/11/2017 22:40, Prasanta Sadhukhan wrote:
>> On 11/28/2017 3:33 AM, Sergey Bylokhov wrote:
>>> Hi, Prasanta.
>>> A few notes about the fix:
>>>  - Can we get an NPE in adjustScrollPositionIfNecessary at
>>>        2391 list.scrollRectToVisible(cellBounds); Not sure that 
>>> scrollRectToVisible is ready for null.
>> cellBounds is not null for this call due to this check in
>>
>> 2308             if (cellBounds != null && 
>> !visRect.contains(cellBounds)) {
>
> In the fix you added a check at line
> 2384 if (cellBounds != null) {
>
> And later you will pass the cellBounds as a parameter:
> 2393                 list.scrollRectToVisible(cellBounds);
>
> So either cellBounds can be null or the new check is not needed.
>
>
>>
>>>  - I think the assignment below can be simplified
>>>        cellBounds = startRect != null ? startRect : null;
>>>  - In the getNextPageIndex() probably we can "return index" 
>>> immediately instead of additional indentation?
>>>
>> Done. Modified webrev
>> http://cr.openjdk.java.net/~psadhukhan/8191639/webrev.01/
>>
>> Regards
>> Prasanta
>>> On 22/11/2017 03:05, Prasanta Sadhukhan wrote:
>>>> Hi All,
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8191639
>>>>
>>>> It is seen that when JList.locationToIndex() or getCellBounds() is 
>>>> overridden to return -1 or null respectively,
>>>> it causes NPE when PageUp/PageDown is pressed in JList.
>>>>
>>>>  From the spec 
>>>> [https://docs.oracle.com/javase/9/docs/api/javax/swing/JList.html#getCellBounds-int-int-] 
>>>>
>>>> of getCellBounds(), it is seen that it can return null under some 
>>>> circumstances. But, JList jdk code assumes it is always non-null.
>>>>
>>>> Proposed fix is to check for null return value of getCellBounds() 
>>>> and bail out.
>>>> webrev: http://cr.openjdk.java.net/~psadhukhan/8191639/webrev.00/
>>>>
>>>> Regards
>>>> Prasanta
>>>
>>>
>>
>
>