public static String formatTimeStampString(Context context, long when) {
  return formatTimeStampString(context, when, false);
}
public static String formatTimeStampString(Context context, long when, boolean fullFormat) {
  Time then = new Time();
  then.set(when);
  Time now = new Time();
  now.setToNow();
  // Basic settings for formatDateTime() we want for all cases.
  int format_flags = DateUtils.FORMAT_NO_NOON_MIDNIGHT |
       DateUtils.FORMAT_ABBREV_ALL |
       DateUtils.FORMAT_CAP_AMPM;
  // If the message is from a different year, show the date and year.
  if (then.year != now.year) {
   format_flags |= DateUtils.FORMAT_SHOW_YEAR | DateUtils.FORMAT_SHOW_DATE;
  } else if (then.yearDay != now.yearDay) {
   // If it is from a different day than today, show only the date.
   format_flags |= DateUtils.FORMAT_SHOW_DATE;
  } else {
   // Otherwise, if the message is from today, show the time.
   format_flags |= DateUtils.FORMAT_SHOW_TIME;
  }
  // If the caller has asked for full details, make sure to show the date
  // and time no matter what we've determined above (but still make showing
  // the year only happen if it is a different year from today).
  if (fullFormat) {
   format_flags |= (DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_TIME);
  }
  return DateUtils.formatDateTime(context, when, format_flags);
}