uigetfile in appdesigner freezes MATLAB

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Biraj Khanal
Biraj Khanal on 13 Jun 2022
Edited: Co Melissant on 17 Apr 2023
In a button click function , I have the following lines of code
file=uigetfile;
app.fileToImport =file;
drawnow;pause(0.05);
The uigetfile somehow pauses the shell. I saw the following error:
Operation terminated by user during matlab.ui.internal.dialog.FileChooser/blockMATLAB (line 390)
In matlab.ui.internal.dialog.FileChooser/showPeerAndBlockMATLAB (line 115)
blockMATLAB(obj);
In matlab.ui.internal.dialog.FileChooser/show (line 122)
obj.showPeerAndBlockMATLAB();
In uigetputfile_helper (line 56)
ufd.show();
In uigetfile (line 130)
[filename, pathname, filterindex] = uigetputfile_helper(0, varargin{:});
In gui2/ImportDataButtonPushed (line 279)
file=uigetfile;
In appdesigner.internal.service.AppManagementService/tryCallback (line 362)
callback(app, event);
In matlab.apps.AppBase>@(source,event)tryCallback(appdesigner.internal.service.AppManagementService.instance(),app,callback,requiresEventData,event)
(line 37)
newCallback = @(source, event)tryCallback(appdesigner.internal.service.AppManagementService.instance(), ...
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 386)
Interrupt while evaluating Button PrivateButtonPushedFcn.
I added the drawnow and pause because I saw that solution somewhere but it does not seem to work. uigetfile worked everytime when I used it out of appdesigner but now it somehow causes the error everytime. I can resume the program somehow and it still works but I do not understand why it is freezing the operation.
I also found the following line
com.mathworks.mwswing.MJFileChooserPerPlatform.setUseSwingDialog(1)
But matlab does not suggest using it. What could be the reason for this and how can it be resolved?
  7 Comments
Biraj Khanal
Biraj Khanal on 15 Jun 2022
Edited: Biraj Khanal on 15 Jun 2022
The function getdata does return data for app.data after some manipulation on temp. I have just not included the line here.
So the function is something like
function data = getdata(app)
temp=importdata(app.fileToImport);
data = temp;
end
I think this is inline with what you wrote above.
"but you do need to load your global in synch with the button;" Sorry, I do not get what you mean by that.
dpb
dpb on 15 Jun 2022
Edited: dpb on 16 Jun 2022
In the code you posted the app.data variable was never being set so you weren't in synch with having data with the button callback...now it is it's there, but I'd not use importdata for this because it can return different formats of the data depending upon the file without notification -- and I'd also strongly recommend to use a fully-qualified file name. I don't know that either of those would trigger the symptoms you're seeing, but they're weak points in the existing code.
We can only see what you post; if that doesn't match the exact code in the app then it's easy (almost guaranteed?) to draw incorrect inferences.
I'd suggest building an independent app with just the uigetfile call and reading the file and then see if the symptom follows -- or if it is only tied into the specific app that indicates there's something elsewhere funky in it. If the symptom is repeated, that would imply something in the OS/Java/the MATLAB install itself.

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Answers (2)

Benjamin Thompson
Benjamin Thompson on 13 Jun 2022
uigetfile is supposed to open a file selection dialog box and let the user select a file? Do you not see that dialog box pop up? It is supposed to pause execution to wait for this input from the user.
  1 Comment
Biraj Khanal
Biraj Khanal on 15 Jun 2022
Yes, I do see the dialog box. It is after i press select/open in the dialog box that MATLAB freezes.

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Co Melissant
Co Melissant on 17 Apr 2023
Edited: Co Melissant on 17 Apr 2023
just add:
com.mathworks.mwswing.MJFileChooserPerPlatform.setUseSwingDialog(1)
The infamous other solution, that also worked for me, and proposed by Yair https://undocumentedmatlab.com/articles/solving-a-matlab-hang-problem
drawnow;
pause(0.5);
drawnow;

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