Help Solve Reset Listbox Error?

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Tom Irvine
Tom Irvine 2012-12-11
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

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采纳的回答

Tom Irvine
Tom Irvine 2012-12-11
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

更多回答（1 个）

Image Analyst
Image Analyst 2012-12-11
编辑：Image Analyst 2012-12-11
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.

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