日期格式化

SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
String dateStr= formatter.format(new Date());

日期加減

SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
Date today = new Date();
Calendar c = Calendar.getInstance();
c.setTime(date);
c.add(Calendar.DAY_OF_MONTH, 1);  //日期加一天，減一隻需把1改為-1
Date tomorrow= c.getTime();
String tomorrowStr = formatter.format(tomorrow);