There is a simpler way in Android
DateFormat.getInstance().format(currentTimeMillis);
Moreover, Date is deprecated, so use DateFormat class.
DateFormat.getDateInstance().format(new Date(0));
DateFormat.getDateTimeInstance().format(new Date(0));
DateFormat.getTimeInstance().format(new Date(0));
The above three lines will give:
Dec 31, 1969
Dec 31, 1969 4:00:00 PM
4:00:00 PM 12:00:00 AM