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

[Sergey Bylokhov]

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.
  - 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?

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.