java日期增加或減少天，當days為負數時為減少的天數，當days為正整數時為增加的天數

public static Date addDays(Date date, int days) {
   Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.add(Calendar.DAY_OF_MONTH, days);
   Date newDay = cal.getTime();
   return newDay;
}

java日期增加或減少月，當months為負數時為減少的月數，當days為正整數時為增加的月數

public static 
 
Date addMonths(Date date, int months) {
   Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.add(Calendar.MONTH, months);
   Date newDay = cal.getTime();
   return newDay;
}

java日期增加或減少小時，當months為負數時為減少的小時數，當days為正整數時為增加的小時數

public static Date addHours(Date date, int hours) {
   Calendar cal = Calendar.getInstance
 
();
   cal.setTime(date);
   cal.add(Calendar.HOUR_OF_DAY, hours);
   Date newDay = cal.getTime();
   return newDay;
}

java日期增加或減少分鐘，當months為負數時為減少的分鐘數，當days為正整數時為增加的分鐘數

public static Date addMinutes(Date date, int minutes) {
   Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.add(Calendar.MINUTE
 
, minutes);
   Date newDay = cal.getTime();
   return newDay;
}