Help Solve Reset Listbox Error?

I have a script that resets two secondary listboxes depending on the value selected from the primary listbox.

Here is a code snippet:

% --- Executes on selection change in toplistbox.
function toplistbox_Callback(hObject, eventdata, handles,output_index)
% hObject    handle to toplistbox (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns toplistbox contents as cell array
%        contents{get(hObject,'Value')} returns selected item from toplistbox

set(handles.Answer,'String',' ');

calculation=get(hObject,'value');

handles.top_index=calculation;

if(calculation==1)  % natural frequency
    clear string;
    set(handles.left_text,'String','Mass');
    string{1}='lbm';
    string{2}='lbf sec^2/in';
    string{3}='kg';
    set(handles.leftlistbox,'String',string)

      set(handles.right_text,'String','Stiffness');
      clear string;
      string{1}='lbf/in';
      string{2}='lbf/ft';
      string{3}='N/m';
      string{4}='N/mm';
      set(handles.rightlistbox,'String',string)

end
if(calculation==2)  % mass
    set(handles.left_text,'String','Natural Frequency');
    clear string;
    string{1}='Hz';
    string{2}='rad/sec';
    set(handles.leftlistbox,'String',string)  

      set(handles.right_text,'String','Stiffness');
      clear string;
      string{1}='lbf/in';
      string{2}='lbf/ft';
      string{3}='N/m';
      string{4}='N/mm';
      set(handles.rightlistbox,'String',string)
  end
  if(calculation==3)  % stiffness
      set(handles.left_text,'String','Natural Frequency');
      clear string;
      string{1}='Hz';
      string{2}='rad/sec';
      set(handles.leftlistbox,'String',string) 

      set(handles.right_text,'String','Mass');
      clear string;
      string{1}='lbm';
      string{2}='lbf sec^2/in';
      string{3}='kg';
      set(handles.rightlistbox,'String',string)
  end    

handles.toplistbox = get(hObject,'value');
guidata(hObject, handles);

• * *The script runs perfectly fine if I run it and exercise various permutations of options a dozen or so times within the run. But eventually, I get an error message such as:

Error using handle.handle/set Invalid or deleted object.

Error in sdof_fn>toplistbox_Callback (line 162) set(handles.leftlistbox,'String',string)

So after a number of times, the leftlistbox becomes invalid. Please help. The full script and figure is available at:

www.vibrationdata.com/matlab2/sdof_fn.zip

Thank you, Tom Irvine

Answer 1

[Tom Irvine]

Thank you Image Analyst.

I found the error. I was inadvertently deleting the secondary listboxes in other Callback functions due to a programmer inexperience/nuance.

Thank you, Tom

Answer 2

[Image Analyst]

handle.handle??? Set "dbstop if error" and examine what handles is when it stops. You could have a problem if the listbox has item 3 selected and then you make it into a list that has only 3 items. Best case the listbox will vanish, worst case it will throw an exception. Make sure you set the value property to 1 before you set the string property.