Max number of checked checkboxes/radiobuttons

Hi i have GUI with 18 checkboxes/radiobuttons. Dont know what is better for me...Is there way to set that only two of them can be checked at the same time?? Thanks.

Answer 1

[Walter Roberson]

Only by using the callbacks to check and enforce it.

[Jakub]

And if i use radiobuttons instead of checkboxes? is there any difference?

[Walter Roberson]

No difference. radiobuttons can be managed by a uibuttongroup() but uibuttongroup() allows either 0 or 1 item to be selected.

[Jakub]

Ok, thanks. Can you give me a siplme example please. How to check how many checkboxes are checked. and if two are checked, uncheck one and check another which i clicked on.

[Image Analyst]

If you don't use a button group you can have each checkbox or radio button's callback call the same function, let's say it's called "CountSelectedStates(handles)". Then in that function, you check the state of each checkbox or radio button. The trouble comes in when you have three selected. You're going to have to remember the last state, say an 1 by 18 array of booleans, and figure out which of the two "old" states should be turned off now that the user has selected a third button or box. So if two are selected, and they select a third, how do you decide which one of the two to turn off?

[Walter Roberson]

If you use something like

function CountSelectedStates(hobject, event, handles)

then hobject will be the handle of the box that was just checked or un-checked; by get(hobject, 'Value') you can figure out if it was just turned on; if it was, then you could set() it off again. In this way you do not need to remember the order of the boxes being checked, you just refuse to let the third one be checked.

Or another approach, using the same calling sequence, would be when the second box was checked, to set() all of the "off" boxes to 'enable', 'off' so that no more can be checked until one of the two active ones is unchecked (at which point you would re-enable all of them.)

[Jakub]

Thank you for advices, i think ill do that when third chechbox is going to be checked, the previous two will be unchecked.

[Jakub]

I dont know how to deal with the function to count selected states...I would appreciate a help, thank you.

[Image Analyst]

function CountSelectedStates(hobject, event, handles)
  % Get states of all the checkboxes.
  selectedStates(1) = get(handles.checkbox1, 'value');
  selectedStates(2) = get(handles.checkbox2, 'value');
  selectedStates(3) = get(handles.checkbox3, 'value');
  selectedStates(4) = get(handles.checkbox4, 'value');
  % Count how many are checked right now.
  totalNumberSelected = sum(selectedStates);
  % Check which one was just toggled
  if hObjects = handles.checkbox1
    % If you want to implement Walter's suggestion.
    % They just clicked on checkbox 1.
    % more code.....
  end
  if totalNumberSelected >= 3
    % Clear states of all the checkboxes, like you wanted.
    selectedStates(1) = get(handles.checkbox1, 'value');
    selectedStates(2) = get(handles.checkbox2, 'value');
    selectedStates(3) = get(handles.checkbox3, 'value');
    selectedStates(4) = get(handles.checkbox4, 'value');
    % Keep the one they clicked on checked.
    set(hObject, 'value', 'on');
  end

and so on.

[Walter Roberson]

Some small corrections to the above:

if hobject == handles.checkbox1

and to clear the check boxes, do not get() the values, instead

set(handles.checkbox1, 'value', 0);