public CFilenameFormatter(final File directory){
  Preconditions.checkArgument(directory.exists(),"Error: Direcctory must exist.");
  m_directory=directory;
}

public CFilenameFormatter ( final File directory ) { Preconditions . checkArgument ( directory . exists ( ) , "Error: Direcctory must exist." ) ; m_directory = directory ; }
filter for jformattedtextfield . ensures valid filenames . does not work for directories .
