1,
Calendar calendar = Calendar.getInstance();
String now = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(calendar.getTime());
2,
String now = new SimpleDateFormat(("yyyy-MM-dd HH:mm:ss").format(new Date());
3,
String now = new SimpleDateFormat(("yyyy-MM-dd HH:mm:ss").format(System.currentTimeMillis());