I'm sure that JFileChooser is quite capable of choosing directories.
However, the documentation is sufficiently obtuse as to make it hard
to figure out, and the things I'm trying just don't cut the mustard.

  JFileChooser dir_chooser = new JFileChooser(".");
  dir_chooser.setDialogType(JFileChooser.DIRECTORIES_ONLY);
  FileFilter ff = new FileFilter() {
public boolean accept(File f) {
if (f.isDirectory()) {
return true;
}
return false;
}
public String getDescription() {
return "Directories";
}
  };
  dir_chooser.setFileFilter(ff);
  dir_chooser.addChoosableFileFilter(ff);

The resulting dialog only shows directories .. however when I double-click
on the dialog, or if I single-click and click the OPEN button, all that
happens is the directory is opened.

It's a highly normal thing to desire to open a directory.

Here's what I've observed on my way to deciding to file this:

1- In the javadoc the sections covering the ChoosableFileFilter list
are horribly inadequately described. Nothing, nada, zip, is there in
the way of describing what the ChoosableFileFilter list is. If just
says circularly referential statements like "Adds a filter to the
list of choosable file filters", without further discussing what
this means.

2- I finally found the trick:

     dir_chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);

However, the claim still is that the documentation is obtuse.

3- The Swing tutorial referenced by the JFileChooser javadoc does not
cover this highly common scenario.