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Creating comboboxes dynamically
I have a panel which i need to add combo boxes as needed.
e.g. start with a blank panel and through an increment and decrement button on a seperate panel, create/remove new comboboxes on the blank panel.
e.g. start with a blank panel and through an increment and decrement button on a seperate panel, create/remove new comboboxes on the blank panel.
Last Comment
CEHJ
Use a vertical BoxLayout and just add/remove them as needed. Call validate and repaint after doing so
ASKER
That's my problem. I don't know how to dynamically create them.
try something like this:
JComboBox combo =new JComboBox();
// initilise combo
panel.add(combo);
panel.revalidate();
panel.repaint();
you'd call it from your buttons action listener
JComboBox combo =new JComboBox();
// initilise combo
panel.add(combo);
panel.revalidate();
panel.repaint();
you'd call it from your buttons action listener
ASKER
the name of all the comboboxes will be 'combo'. How do I differentiate between them?
You need something like
void addCombo(ComboBoxModel model) {
JComboBox cb = new JComboBox(model);
combosList.add(cb);// Keep in collection so the reference not lost
panel.add(cb);
validate();
repaint();
}
void addCombo(ComboBoxModel model) {
JComboBox cb = new JComboBox(model);
combosList.add(cb);// Keep in collection so the reference not lost
panel.add(cb);
validate();
repaint();
}
>>How do I differentiate between them?
Rather than use a List as i suggested, you could also use a Map
Rather than use a List as i suggested, you could also use a Map
> validate();
should be revalidate()
see the code i posted above
should be revalidate()
see the code i posted above
> You need something like
and thats already been mention, please have read of all other comments before posting to avoid confusing the asker
and thats already been mention, please have read of all other comments before posting to avoid confusing the asker
ASKER
>> combosList.add(cb)
what is actually being stored here? And how would I use it to gain access to the combobox.
what is actually being stored here? And how would I use it to gain access to the combobox.
> what is actually being stored here? And how would I use it to gain access to the combobox.
the combo, but its unnecessary and makes it harder to maintain.
You should avoid references to every component in your gui to make your app easier to manage.
Instead use listeners that react when a change occurs in the gui.
the combo, but its unnecessary and makes it harder to maintain.
You should avoid references to every component in your gui to make your app easier to manage.
Instead use listeners that react when a change occurs in the gui.
ASKER
but I still need to attach data to the combobox (datamodel?) in the first instance then retrieve at some point.
My question is (and this is where I show myself up as a begineer) how do I know which combo box it is as they are all havethe same name. Or am i missing a trick here ;)
My question is (and this is where I show myself up as a begineer) how do I know which combo box it is as they are all havethe same name. Or am i missing a trick here ;)
>>what is actually being stored here? And how would I use it to gain access to the combobox.
The reference to the combo so that it can be accessed. Listeners, btw, are there to provide messaging capabilities between components, *not* to provide references, which you will need to use for direct access. Furthermore, if you don't have a reference to the component in the GUI, it will actually disappear
The reference to the combo so that it can be accessed. Listeners, btw, are there to provide messaging capabilities between components, *not* to provide references, which you will need to use for direct access. Furthermore, if you don't have a reference to the component in the GUI, it will actually disappear
>>how do I know which combo box it is as they are all havethe same name. Or am i missing a trick here ;)
A name and a reference are different things. How do you *want* to differentiate between them? IOW how do you know by looking which is which?
A name and a reference are different things. How do you *want* to differentiate between them? IOW how do you know by looking which is which?
typically you create your model when you create the combo, even if its empty.
You can then get the state from the model. You rarely need to access the combo directly once it has been added to your combo.
Plus references to the combo (and model) are passed to the listner when a change occurs.
(and the panel also stores references to the combos if you're desperate)
You can then get the state from the model. You rarely need to access the combo directly once it has been added to your combo.
Plus references to the combo (and model) are passed to the listner when a change occurs.
(and the panel also stores references to the combos if you're desperate)
ASKER
Your underestimating my ignorance.
Say, I have pressed the 'add' button three times and created 3 comboboxes. For argumants sake they all contain lists of countries. My user has selected three different countries (one for each combo) and I now need to do something with it.
Because I know how many there are I could loop through the List I created, has you suggested CEHJ, is it a case of
Class comboHolder;
comboHolder = comboList(i);
Does the Class (comboHolder) I created now behave as the class JCombobox??
Please excuse the poor terminlogy!!
Say, I have pressed the 'add' button three times and created 3 comboboxes. For argumants sake they all contain lists of countries. My user has selected three different countries (one for each combo) and I now need to do something with it.
Because I know how many there are I could loop through the List I created, has you suggested CEHJ, is it a case of
Class comboHolder;
comboHolder = comboList(i);
Does the Class (comboHolder) I created now behave as the class JCombobox??
Please excuse the poor terminlogy!!
ASKER
objects - I wrotemy reply before refreshing and didn't see you comment.
If I use a listener - then again I need to know which combo i am listening to - that's the bit I don't understand. All I know is that is belongs to a certain panel. I have no means of establishing which it may be.
If I use a listener - then again I need to know which combo i am listening to - that's the bit I don't understand. All I know is that is belongs to a certain panel. I have no means of establishing which it may be.
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