android: long number to date format

The function is as follows:

    public String test(String beginDate) {
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String sd = sdf.format(new Date(Long.parseLong(beginDate)));
        return sd;
    }

transfer:

 update_at.setText(test(“20110219”));

end～