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

[Sergey Bylokhov]

On 27/11/2017 23:45, Prasanta Sadhukhan wrote:
> Ok. I have added the check for scrollRectToVisible() too.
> 
> http://cr.openjdk.java.net/~psadhukhan/8191639/webrev.02

Should the test use some specific L&F? Currently it is pass on macOS and 
Aqua L&F before the fix.

> 
> 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
>>>>
>>>>
>>>
>>
>>
> 


-- 
Best regards, Sergey.