按指定天数计算日期

Question

我使用 Android Studio。我想从我指定的日期计算280天后的那一天。

Calendar thatDay = Calendar.getInstance(); //today date
thatDay.set(Calendar.DAY_OF_MONTH,selectedday);
thatDay.set(Calendar.MONTH,selectedmonth-1); // 0-11 so 1 less
thatDay.set(Calendar.YEAR, selectedyear);


Calendar afterday= Calendar.getInstance(); //280 after date
afterday.set(Calendar.DAY_OF_MONTH,selectedday+10);
afterday.set(Calendar.MONTH,selectedmonth+8); 
afterday.set(Calendar.YEAR, selectedyear);

Log.e(" After Day: ", " days:" +  (afterday.getTimeInMillis()- thatDay.getTimeInMillis())/ (24 * 60 * 60 * 1000));

日志输出变量。有时285283279种

Answer 1

简单cal.add(Calendar.DATE, 280);

Answer 2

    LocalDate myDate = LocalDate.now();
    LocalDate datePlusDays = myDate.plusDays(280);
    System.out.println("Today Plus 280 Days: " + datePlusDays);