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

[Alexander Potochkin]

> 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)...

I second Pavel, "<? extends E>" doesn't work well for getters/setters

#2 is preferable

Thanks
alexp

> 
> 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
>>
>>
>