Re: How to update JComboBox without Selected Item being changed

From:

Nigel Wade <nmw@ion.le.ac.uk>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 15 Dec 2006 12:12:15 +0000

Message-ID:

<elu3ev$9i3$1@south.jnrs.ja.net>

J??rgen Gerstacker wrote:

Hello,
I want to periodically update a Combobox due to changes in the OS
(available RS232 serial ports).
I started to fill the box every time the combobox becomes visible

setup_cbport.removeAllItems();
while () {
  ...
  setup_cbport.addItem(portId.getName());
  ...
}
setup_cbport.setSelectedItem(port); // previously selected item

But when the box is being filled, an actionPerformed is fired

public void actionPerformed(ActionEvent e) {
if (e.getSource()==setup_cbport) {
  Object obj=setup_cbport.getSelectedItem();
  port=(String)obj; // new selection
}

and the previous selected item is overwritten.

I could compare the items in the box with the new items and
'add'/'remove' individually but this would complicated the code. I
would like a simple solution, e.g. to allow the new selection only when
the user changes the ComboBox, not when the 'actionPerformed' is issued
by the System.
Any ideas?

Juergen

You could remove the listeners before updating the ComboBox, then restore them
after the update is complete:

ActionListener[] listeners = setup_cbport.getActionListeners();
for(ActionListener l:listeners) {
setup_cbport.removeActionListener(l);
}

// do whatever you need to here.

for(ActionListner l:listeners) {
setup_cbport.addActionListener(l);
}

--
Nigel Wade, System Administrator, Space Plasma Physics Group,
University of Leicester, Leicester, LE1 7RH, UK
E-mail : nmw@ion.le.ac.uk
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555