<Swing Dev> 6179357: Generics: JList: Constructors & Model

[Pavel Porvatov]

Hi Florian,

I'd like more consistent variant #2 because of the 
javax.swing.ComboBoxModel#setSelectedItem() method prevents to use 
construction like "<? extends E>" in the JComboBox class (as you noticed 
before)...

Regards, Pavel.

> This one is still open...
> Opinions?
> 
> -Florian
> 
> Am Donnerstag, 26. Februar 2009 schrieb Florian Brunner:
>> So, which approach do we take? I'm tending now more towards approach 1) but
>> approach 2) would be fine for me, too?
>>
>> Pavel? Anyone else?
>>
>> -Florian
>>
>> Am Samstag, 21. Februar 2009 schrieb Florian Brunner:
>>> In the case of JComboBox I think it's not even possible to define
>>> something like:
>>>
>>>  class JComboBox<E>{
>>>  ComboBoxModel<? extends E> getModel();
>>>  setModel(ComboBoxModel<? extends E>);
>>>  }
>>>
>>> because JComboBox internally uses the ComboBoxModel.setSelectedItem
>>> method.
>>>
>>> So the question is what do you think is better:
>>>
>>> 1) To look at each component individually and try to make each as
>>> flexible as possible. So in the JList/ JComboBox case this would mean:
>>>
>>>  class JList<E>{
>>>  ListModel<? extends E> getModel();
>>>  setModel(ListModel<? extends E>);
>>>  }
>>>
>>> but
>>>
>>>  class JComboBox<E>{
>>>  ComboBoxModel<E> getModel();
>>>  setModel(ComboBoxModel<E>);
>>>  }
>>>
>>> 2) Make the interfaces as consistent as possible over all components.
>>> This would mean for the JList case to use somethink like:
>>>  class JList<E>{
>>>  ListModel<E> getModel();
>>>  setModel(ListModel<E>);
>>>  }
>>>
>>> This approach is slightly less flexible than the approach 1), but cases
>>> where one could benefit from approach 1) are probably rare and there are
>>> various work-arounds (like: wrapping the model/ use a common base class
>>> for the generic parameter/ use raw type/... )
>>>
>>> So what do you think? Approach 1) or 2)?
>>>
>>> -Florian
>>>
>>> Am Donnerstag, 19. Februar 2009 schrieb Florian Brunner:
>>>> Well, there is probably no big issue with JList, because the ListModel
>>>> is immutable.
>>>>
>>>> But when we add generics to JComboBox, which is similar to JList, the
>>>> situation is a bit more controversial, because the ComboBoxModel is
>>>> mutable.
>>>>
>>>> So if we have something like this:
>>>> class JComboBox<E>{
>>>> ComboBoxModel<? extends E> getModel();
>>>> setModel(ComboBoxModel<? extends E>);
>>>> }
>>>>
>>>> then something like this is not possible:
>>>> JComboBox<Foo> cb = new JComboBox<Foo>(...);
>>>> ...
>>>> Foo foo;
>>>> ComboBoxModel<? extends Foo> model = cb.getModel();
>>>> model.setSelectedItem(foo); -> compile time error
>>>>
>>>> You would need to do an unchecked (-> not type-safe) cast first:
>>>> ComboBoxModel<Foo> model = (ComboBoxModel<Foo>) cb.getModel();
>>>>
>>>> And type-safty is what generics is all about.
>>>>
>>>> -Florian
>>>>
>>>> Am Dienstag, 3. Februar 2009 schrieb Pavel Porvatov:
>>>>> Hi Florian,
>>>>>
>>>>>> ----------------------------------------
>>>>>>
>>>>>> public JList(ListModel dataModel)
>>>>>>
>>>>>> {
>>>>>>
>>>>>> if (dataModel == null) {
>>>>>>
>>>>>> throw new IllegalArgumentException("dataModel must be non null");
>>>>>>
>>>>>> }
>>>>>>
>>>>>> // Register with the ToolTipManager so that tooltips from the
>>>>>>
>>>>>> // renderer show through.
>>>>>>
>>>>>> ToolTipManager toolTipManager = ToolTipManager.sharedInstance();
>>>>>>
>>>>>> toolTipManager.registerComponent(this);
>>>>>>
>>>>>> layoutOrientation = VERTICAL;
>>>>>>
>>>>>> this.dataModel = dataModel;
>>>>>>
>>>>>> selectionModel = createSelectionModel();
>>>>>>
>>>>>> setAutoscrolls(true);
>>>>>>
>>>>>> setOpaque(true);
>>>>>>
>>>>>> updateUI();
>>>>>>
>>>>>> }
>>>>>>
>>>>>> --->
>>>>>>
>>>>>> public JList(ListModel<E> dataModel)
>>>>>>
>>>>>> {
>>>>>>
>>>>>> if (dataModel == null) {
>>>>>>
>>>>>> throw new IllegalArgumentException("dataModel must be non null");
>>>>>>
>>>>>> }
>>>>>>
>>>>>> // Register with the ToolTipManager so that tooltips from the
>>>>>>
>>>>>> // renderer show through.
>>>>>>
>>>>>> ToolTipManager toolTipManager = ToolTipManager.sharedInstance();
>>>>>>
>>>>>> toolTipManager.registerComponent(this);
>>>>>>
>>>>>> layoutOrientation = VERTICAL;
>>>>>>
>>>>>> this.dataModel = dataModel;
>>>>>>
>>>>>> selectionModel = createSelectionModel();
>>>>>>
>>>>>> setAutoscrolls(true);
>>>>>>
>>>>>> setOpaque(true);
>>>>>>
>>>>>> updateUI();
>>>>>>
>>>>>> }
>>>>>>
>>>>>> We could define the signature also like this:
>>>>>>
>>>>>> public JList(ListModel<? extends E> dataModel)
>>>>>>
>>>>>> but then we would have to define the dataModel-field also with:
>>>>>>
>>>>>> private ListModel<? extends E> dataModel
>>>>>>
>>>>>> as well as the model-property. I don't think this would be a good
>>>>>> idea and thus define the signature as:
>>>>>>
>>>>>> public JList(ListModel<E> dataModel)
>>>>>>
>>>>>> What do you think?
>>>>> Why do you think that "private ListModel<? extends E> dataModel" is
>>>>> not a very good idea?
>>>>>
>>>>> Regards, Pavel
> 
>