ERROR USING SET() ? GUI, Handles

Question

Paulo 2011-8-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14649-error-using-set-gui-handles

my code is like this: while microcontroller is connected

if(face detected) set(handles.statusLbl,'String','Capturing iris image . . .'); else set(handles.statusLbl,'String','Idle');

end while

statusLbl is a static text in the GUI

And When I exit the program, an error occurs...

 Error using
==> set
Invalid handle
object.

Error in ==> irisrecognition>irisrecognition_OpeningFcn at 124 set(handles.statusLbl,'String','Idle');

Error in ==> gui_mainfcn at 221 feval(gui_State.gui_OpeningFcn, gui_hFigure, [], guidata(gui_hFigure), varargin{:});

Error in ==> irisrecognition at 42 gui_mainfcn(gui_State, varargin{:});

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Jan 2011-8-27

What is your question?

You can use the debugger ("dbstop if error") to find out, why the opening function is called when you stop the program. But there is no chance, that we can guess the cause of the problem.

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Answer 1

Paulo Silva 2011-8-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14649-error-using-set-gui-handles#answer_19903

It looks like you have your code inside a while loop, when you exit your GUI the handles are deleted but the loop still tries to set the string of the static text (at least once), the fast solution would be:

try
    if(face detected)
       set(handles.statusLbl,'String','Capturing iris image . . .'); 
    else
         set(handles.statusLbl,'String','Idle')
    end
catch
end

The best solution would involve checking if the handles.statusLbl is still a valid handle before setting the text string.

Some functions that might be helpful

any(ismember(who,'handles')) %check if theres one handles variable
strcmp(class(handles),'struct') %check if handles is a structure
isfield(handles,'statusLbl') %check if handles got one field called statusLbl
ishandle(handles.statusLbl) %check if the statusLbl is a valid handle