GUI to select a file if it exists else create a new one

Hi,

As part of my application, I need a GUI-based approach to select a file. It should basically allow the user to select a file, if it exists (return full file path similar to uigetfile) else return the fullpath of the filename entered manually in the file selection dialog (similar to uiputfile). All my application needs is a filepath for its operation.

I have tried uigetfile() but it throws an error if the filename entered does not exist. I tried putting it in try.. catch.. construct but I believe the error is handled internally in uigetfile. If I use uiputfile(), when an existing file is selected, it asks whether the file should be replaced.

I was wondering if there is a setting in either of these built-in functions to achieve what I'm trying to do.

If possible, I'd like to avoid generating a custom UI for something as simple as this.

Any pointers would be really appreciated.

Cheers,

sunny

[Sunny Talekar]

I know uiputfile() does not actually overwrite the file. However, the dialog box asking the user to confirm replacing the existing file can cause confusion.

Answer 1

[Luna]

Hi Sunny,

[fileName,pathName,index] = uiputfile({'*.xlsx';'*.xls'},'Please Select a file Location','My Default File Name.xlsx');
if index % if user selects a target location for his/her file no matter if it is a new file name(which does not exist) or existing file name index will be 1.
    fullfilePath = fullfile(pathName,fileName)
else % if user presses cancel and does not select anything, index will be 0.
    return % user didn't select so return
end

The natural behaviour of the replacement file is Window's behaviour. So if a file already exists, it will always ask for replacement.

You can also do that:

1. Ask for a file name with inputdlg function from user
2. Ask for a folder path name with uigetdir (it only allows selecting folder not a file) from user.
3. Combine pathName and fileName from those 2 inputs from user with fullfile function and continue working on it.

The third method you can apply is a java hack directly gets you the full file name with path:

parframe = com.mathworks.hg.peer.utils.DialogUtilities.createParentWindow;
obj = javahandle_withcallbacks.com.mathworks.mwswing.MJFileChooser;
obj.showOpenDialog(parframe);
filename = char(obj.getSelectedFile);

Note that if user selects an existing file, and you are going to save something on that full file name, it will definetely overwrite the existing file.

[Sunny Talekar]

Hi Luna

Thanks for the java snippet.

I just expanded that a bit and now it does exactly what I was looking for.

The replace existing message when using uiputfile() was causing a bit of confusion for the users so I wanted a way to get rid of it. And the java solutuin that you suggested was perfect.

[Luna]

Your welcome :)