code: @Override
      public void prepareToWriteJournalEntry() throws JournalException {
          if (open) {
              currentJournal.closeIfAppropriate();
  
              if (!currentJournal.isOpen()) {
                  currentJournal =
                          new JournalOutputFile(this,
                                                filenamePrefix,
                                                journalDirectory,
                                                sizeLimit,
                                                ageLimit);
              }
          }
      }
docs: Before writing an entry, check to see whether we need to close the
  current file and/or open a new one.