DateUtils should use the user's 12/24-hour preference, not the locale's.

     */

    public static Formatter formatDateRange(Context context, Formatter formatter, long startMillis,

                                            long endMillis, int flags, String timeZone) {

        // icu4c will fall back to the locale's preferred 12/24 format,

        // but we want to fall back to the user's preference.

        if ((flags & (FORMAT_12HOUR | FORMAT_24HOUR)) == 0) {

            flags |= DateFormat.is24HourFormat(context) ? FORMAT_24HOUR : FORMAT_12HOUR;

        }

        String range = DateIntervalFormat.formatDateRange(startMillis, endMillis, flags, timeZone);

        try {

            formatter.out().append(range);