code: public static boolean exists(@NonNull String name, @NonNull File directory) {
          if (name == null) { throw new IllegalArgumentException("name cannot be null."); }
          if (directory == null) { throw new IllegalArgumentException("directory cannot be null."); }
          return getDatabasePath(directory, name).exists();
      }
docs: Checks whether a database of the given name exists in the given directory or not.
  
  @param name      the database's name
  @param directory the path where the database is located.
  @return true if exists, false otherwise.