Making a dialog where the user can choose either a file or a folder

In MATLAB, there's a function that prompts the user to choose one or more files - uigetfile, and there's another function which allows the user to choose a folder - uigetdir.

I would like to provide the user an ability to choose either a file or a folder, using a single window, as this is important for the UX I'm trying to create.

So far, the only solution I found that uses the above functions¹ requires an additional step of asking the user what type of entity they would like to select, in advance, and calling the appropriate function accordingly - which I find inconvenient.

So how can I have a dialog which allows me to select either one?

We can use a Java component for this, specifically JFileChooser, and make sure that we provide it with the FILES_AND_DIRECTORIES selection flag.

%% Select entity:
jFC = javax.swing.JFileChooser(pwd);
jFC.setFileSelectionMode(jFC.FILES_AND_DIRECTORIES);
returnVal = jFC.showOpenDialog([]);
switch returnVal
  case jFC.APPROVE_OPTION
    fName = string(jFC.getSelectedFile());
  case jFC.CANCEL_OPTION
    % do something with cancel
  case jFC.ERROR_OPTION
    % do something with error
  otherwise
    throw(MException("fileFolderChooser:unsupportedResult", ...
                     "Unsupported result returned from JFileChooser: " + returnVal + ...
                     ". Please consult the documentation of the current Java version (" + ...
                     string(java.lang.System.getProperty("java.version")) + ")."));
end

%% Process selection:
switch true % < this is just some trick to avoid if/elseif
  case isfolder(fName)
    % Do something with folder
  case isfile(fName)
    % Do something with file
  otherwise
    throw(MException('fileFolderChooser:invalidSelection',...
                     'Invalid selection, cannot proceed!'));
end

This produces a familiar-looking dialog as follows, which works exactly as expected:

JFileChooser has a variety of interesting settings like multi-selection and showing hidden files/folders, as well as standard settings like changing the dialog title, the button texts and tooltips, etc. It can also be used as either an "Open" dialog or a "Save" dialog simply by setting a value.

Tested on R2018a, with Java 1.8.0_144 (output of java.lang.System.getProperty("java.version")).