<Swing Dev> [11] Review Request: JDK-5076761 : JList.setSelectedValue(null, ...) doesn't do anything

[Semyon Sadetsky]

Can you explain what is wrong with the suggested  approach?  It is 
flexible to handle both null and non-null containing JList.


On 01/05/2018 04:25 PM, Sergey Bylokhov wrote:
> I doubt that support of null values in the data model is intentional 
> because JList is "A component that displays a list of *objects* and 
> allows the user to select one or more items."
>
> The null behavior was not specified and work in most cases because 
> some of the getXXX methods in ListModel sub-classes and JList have a 
> special meaning of null:
>
> JList.getSelectedValue(): Returns {@code null} if there is no selection.
> ListModel.getElementAt(int index): In most cases implemented to return 
> null if index is incorrect.
>
> Similar method TableModel.getValueAt(int,int) is also usually 
> implemented to return null if value is not found or some error occured.
>
> JComboBox.setSelectedItem(): use <code>null</code> to clear the selection
> ComboBoxModel.setSelectedItem(): <code>null</code> to clear the selection
> ComboBoxModel.getSelectedItem(): <code>null</code> if there is no 
> selection
>
> So I suggest to follow initial intention here, because it is too late 
> to add validation of the values.
>  - The null value in get() will mean no-selection.
>  - The null value passed to set() will clear selection.
>
> On 05/01/2018 02:15, Pankaj Bansal wrote:
>> Hi Semyon/Sergey,
>>
>> Yes, JList can contain null elements as it can be added to data 
>> model. I think this changes a lot in this bug. I think the selection 
>> needs to be cleared when the object passed is not present in the 
>> list, irrespective of it being null or not. I have made code changes. 
>> Please have a look.
>>
>> Webrev: http://cr.openjdk.java.net/~pbansal/5076761/webrev.02/
>>
>> Regards,
>> Pankaj Bansal
>>
>> -----Original Message-----
>> From: Semyon Sadetsky
>> Sent: Friday, January 5, 2018 6:59 AM
>> To: Pankaj Bansal; swing-dev at openjdk.java.net
>> Subject: Re: <Swing Dev> [11] Review Request: JDK-5076761 : 
>> JList.setSelectedValue(null, ...) doesn't do anything
>>
>> Hi Pankaj,
>>
>> Can JList contain null value?
>>
>> --Semyon
>>
>>
>> On 01/02/2018 11:26 PM, Pankaj Bansal wrote:
>>> Hi Sergey,
>>>
>>> Thanks for the review.
>>>
>>> I have made the suggested changes. Please have a look.
>>> webrev: http://cr.openjdk.java.net/~pbansal/5076761/webrev.01/
>>>
>>> Regards,
>>> Pankaj Bansal
>>>
>>>
>>> -----Original Message-----
>>> From: Sergey Bylokhov
>>> Sent: Wednesday, January 3, 2018 3:31 AM
>>> To: Pankaj Bansal; swing-dev at openjdk.java.net; Prasanta Sadhukhan
>>> Subject: Re: [11] Review Request: JDK-5076761 :
>>> JList.setSelectedValue(null, ...) doesn't do anything
>>>
>>> Hi, Pankaj.
>>> The fix looks fine, but I suggest to update the spec as well and 
>>> describe the behavior if "null" value is passed.
>>>
>>> On 02/01/2018 02:07, Pankaj Bansal wrote:
>>>> Hi All,
>>>>
>>>> Please review the fix for JDK 11.
>>>>
>>>> Bug:
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-5076761
>>>>
>>>> Webrev:
>>>>
>>>> http://cr.openjdk.java.net/~pbansal/5076761/webrev.00/
>>>>
>>>> Issue:
>>>>
>>>> When setSelectedValue is called on JList with null object, it should
>>>> clear all selection. But it is not doing anything.
>>>>
>>>> Fix:
>>>>
>>>> In setSelectedValue if the object is null, the setSelectedIndex is
>>>> called with -1. but this does not clear the selection. We should be
>>>> calling clearSelection instead of SetSelectedIndex.
>>>>
>>>> Regards,
>>>>
>>>> Pankaj Bansal
>>>>
>>>
>>> -- 
>>> Best regards, Sergey.
>>
>
>