code: public String readLine(String format, Object... args) {
          synchronized (CONSOLE_LOCK) {
              format(format, args);
              return readLine();
          }
      }
docs: Reads a line from this console, using the specified prompt.
  The prompt is given as a format string and optional arguments.
  Note that this can be a source of errors: if it is possible that your
  prompt contains {@code %} characters, you must use the format string {@code "%s"}
  and pass the actual prompt as a parameter.
  
  @param format the format string (see {@link java.util.Formatter#format})
  @param args
  the list of arguments passed to the formatter. If there are
  more arguments than required by {@code format},
  additional arguments are ignored.
  @return the line, or null at EOF.