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

[Semyon Sadetsky]

On 01/16/2018 09:47 AM, Sergey Bylokhov wrote:
> On 08/01/2018 08:25, Semyon Sadetsky wrote:
>>> On 05/01/2018 18:01, Semyon Sadetsky wrote:
>>>> Can you explain what is wrong with the suggested  approach?  It is 
>>>> flexible to handle both null and non-null containing JList.
>>>
>>> Because it is wrong direction try to support some approach which is 
>>> undefined behavior. The null has a special meaning in 
>>> JList.getSelectedValue/setSelectedValue() as well as in a few other 
>>> methods mentioned below. The usage of unspecified null values may 
>>> result in a run time exception either immediately or at some later 
>>> time.
>> I didn't find any spec that mentions null as a special value
>
> I already listed a methods which use null as an absent of the value. 
> And current methods were implemented with this intention.
But JList is fully usable without them.
>
>>  as well as any pointer that JList couldn't contain null.
>
> There are no references to null in the javadoc which means that null 
> is unsupported. By default the null value is unsupported, and it can 
> be considered as supported only if spec accept that.
That is a good argument that proves that null is not considered as a 
special value.
>
>> getSelectedValue() may not be an indicator because there are several 
>> replacements setSelectedIndex(), setSelectedIndices(), 
>> getSelectedValues(), getSelectedValuesList() which supports null.
>> Other components are unrelated.
> Why JComboBox.setSelectedItem() and JList.setSelectedValue() are 
> unrelated? Both are quite similar and have similar logic. Moreover 
> JComboBox.setSelectedItem() has much more detailed description which 
> we should use as an example.
>
Those are different type of controls. For example, in JComboBox 
setSelectedIndex(-1) clears selection unlike JList. Why you don't 
propose to fix the current issue by making setSelectedIndex(-1) clearing 
selection in JList?
And JComboBox may contain null as well.
If we look at JFX ListView it may also contain null.