Setting a limit on number of items selected in a JList

Question

hi guys,
I have a JList in my swing application. The default Selection mode is Multiple-interval Selection.
But actually i want to select a maximum of only 3 items at a time from the list, so can anyone help how to fine tune this selection criteria.
Thanks,
vishal

Answer 1

The 'proper' way would be to implement ListSelectionModel (either directly or through DefaultListSelectionModel) and implement the functionality you want. You will need to override the setSelection methods (i.e. addSelectionInterval, setSelectionInterval etc) with something like:
public void setSelectionInterval(int index0, int index1) {
   if ((index1 - index0) < maxSelectionCount) {
      super.setSelectionInterval(index0, index1);
// ... etcYou will need to decide what you want to happen when a user tries to select a fourth item, you could either ignore the request (probably the easiest) or you could deselect one of their other choices.
As a side note, I dont think that limiting the number of selections on a list is a very intuaive interface design. I don't know what the ideal solution would be, maybe a collection of three combo boxes or something like that.