code: @InterfaceAudience.Public
      public List<String> getAllDatabaseNames() {
          String[] databaseFiles = directoryFile.list(new FilenameFilter() {
  
              @Override
              public boolean accept(File dir, String filename) {
                  if (filename.endsWith(Manager.kDBExtension)) {
                      return true;
                  }
                  return false;
              }
          });
          List<String> result = new ArrayList<String>();
          for (String databaseFile : databaseFiles) {
              String trimmed = databaseFile.substring(0, databaseFile.length() - Manager.kDBExtension.length());
              String replaced = trimmed.replace(':', '/');
              result.add(replaced);
          }
          Collections.sort(result);
          return Collections.unmodifiableList(result);
      }
docs: An array of the names of all existing databases.