code: private File createFilename(String filenamePrefix, File journalDirectory)
              throws JournalException {
          String filename =
                  JournalHelper.createTimestampedFilename(filenamePrefix,
                                                          new Date());
          File theFile = new File(journalDirectory, filename);
  
          if (theFile.exists()) {
              throw new JournalException("File '" + theFile.getPath()
                      + "' already exists.");
          }
  
          return theFile;
      }
docs: Create a <code>File</code> object with the name of this Journal file.
  Check to be sure that no such file already exists.