<Swing Dev> [10] RFR: 8182577: Crash when Tab key moves focus to a JCheckbox with a custom ButtonModel

[Luke Usherwood]

Hi Semyon,

I'm felling guilty & would like to apologise once again for nit-picking. 
The ButtonModel basically defines some observable properties which do 
not otherwise have behaviour (unless someone has gone and created some 
horrendous mix-in abomination with it - unlikely). So I am being 
unreasonable to be concerned about this point.

Please do proceed with either the original text or your suggestion! :-)

Kind regards,
Luke


On 03/07/2017 12:42, Luke wrote:
> Hi Semyon,
>
> On 30/06/2017 17:45, Semyon Sadetsky wrote:
>> I would change the spec to
>>
>> +    * @return the <code>ButtonGroup</code> that the button belongs 
>> to or null otherwise
>>
>> Because if the getter returns null the button doesn't actually belong 
>> to any group, and this is true for both legacy and after 
>> implementations.
>> But the current spec looks ok to me as well.
>>
> FYI: this sentence contains the logical mistake that I could see users 
> falling for.  A legacy ButtonModel may continue to hold a non-null 
> ButtonGroup reference and implement its behaviour accordingly: that it 
> is now in a group. A caller that assumes getGroup() == null means 
> _only_ that the model is not in a group would be mislead.  
> Occasionally callers might need to handle the legacy case to ensure 
> everything behaves consistently - such as by maintaining their own 
> reference to the ButtonGroup externally. But I accept the need to 
> distinguish would be seldom.
>
> I'm sorry I was not able to describe this better in my earlier emails 
> - only by discussing it I reached clarity on what initially "bugged" 
> me about the default implementation myself.
>
> Anyway, I will leave this thought with you.
>
> Kind regards,
> Luke
>