SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    
        Date d1 = null;
        Date d2 = null;
    
        try {
            d1 = format.parse(dateStart);
            d2 = format.parse(dateStop);
    
            //毫秒ms
            long diff = d2.getTime() - d1.getTime();
    
            long diffSeconds = diff / 1000 % 60;
            long diffMinutes = diff / (60 * 1000) % 60;
            long diffHours = diff / (60 * 60 * 1000) % 24;
            long diffDays = diff / (24 * 60 * 60 * 1000);
    
            System.out.print("兩個時間相差：");
            System.out.print(diffDays + " 天, ");
            System.out.print(diffHours + " 小時, ");
            System.out.print(diffMinutes + " 分鐘, ");
            System.out.print(diffSeconds + " 秒.");
    
        } catch (Exception e) {
            e.printStackTrace();
        }