code: public final static DateFormat getDateTimeInstance(
          int dateStyle, int timeStyle, ULocale locale)
      {
          return get(dateStyle, timeStyle, locale, null);
      }
docs: Returns the date/time formatter with the given formatting styles
  for the given locale.
  @param dateStyle the given date formatting style. As currently implemented, relative date
  formatting only affects a limited range of calendar days before or after the
  current date, based on the CLDR &lt;field type="day"&gt;/&lt;relative&gt; data: For example,
  in English, "Yesterday", "Today", and "Tomorrow". Outside of this range, relative
  dates are formatted using the corresponding non-relative style.
  @param timeStyle the given time formatting style. Relative time styles are not
  currently supported, and behave just like the corresponding non-relative style.
  @param locale the given ulocale.
  @return a date/time formatter.