如何计算从给定日期算起的X天数？

Question

我能到102天添加到任何日期我输入，但现在的问题是，它应该是102周天（不包括周末）。 我怎样才能做到这一点？

这是我仅增加102天的代码：

private void txtStartKeyReleased(java.awt.event.KeyEvent evt) {
    try {    
        Date date1 = new SimpleDateFormat("yyyy-MM-dd").parse(txtStart.getText());

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");     
        Calendar cal  = Calendar.getInstance();
        cal.setTime(date1);
        cal.add(Calendar.DATE, 102);
        String expDateString = sdf.format(cal.getTime());
        txtExpiry.setText(expDateString);
    } catch (ParseException ex) {
        Logger.getLogger(ClientInfo.class.getName()).log(Level.SEVERE, null, ex);
    } 
}

Answer 1

接下来呢？

for (int i = 1; i <= 102; i++)
{
    DateTime thisOne = DateTime.Parse("2012-03-13");

    string thisDay = thisOne.ToString("dddd");

    if (thisDay != "Saturday" && thisDay != "Sunday")
    {
        cal.add(Calendar.DATE, i);
    }
}

编辑：已更新自定义日期

Answer 2

我只是粘贴了仅排除周末的代码段。 请根据您的目的使用

int numberOfDays = 102;
int count = 1;
String expDateString = null;
Date temp = date1;
while(count != numberOfDays){
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");     
    Calendar cal  = Calendar.getInstance();
    cal.setTime(temp);
    int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK );
    if(!(dayOfWeek == Calendar.SATURDAY || dayOfWeek == Calendar.SUNDAY)){
        cal.add(Calendar.DATE, count);
        count++;
    }
    temp = cal.getTime();
    expDateString = sdf.format(cal.getTime());
}

Answer 3

这应该将weekdays工作日（忽略周末）添加到日期上。 如果您在weekdays通过0 ，它将获得下一个工作日。 因此， Saturday + 1 weekday = Tuesday 。

private static Date addWeekdaysToDate(Date date, int weekdays) {
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    int originalDayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
    int numWeeks = weekdays / 5;
    int remainderDays = weekdays % 5;
    cal.add(Calendar.DAY_OF_MONTH, numWeeks * 7 + remainderDays);

    int adjustmentDays = 0;
    if (originalDayOfWeek == Calendar.SUNDAY) {
        adjustmentDays = 1;
    } else if (originalDayOfWeek + remainderDays > Calendar.FRIDAY) {
        adjustmentDays = 2;
    }
    cal.add(Calendar.DAY_OF_MONTH, adjustmentDays);
    return cal.getTime();
}

编辑：

在您的代码中，只需替换为以下内容：

private static Date addWeekdaysToDate(Date date, int weekdays) {
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    int originalDayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
    int numWeeks = weekdays / 5;
    int remainderDays = weekdays % 5;
    cal.add(Calendar.DAY_OF_MONTH, numWeeks * 7 + remainderDays);

    int adjustmentDays = 0;
    if (originalDayOfWeek == Calendar.SUNDAY) {
        adjustmentDays = 1;
    } else if (originalDayOfWeek + remainderDays > Calendar.FRIDAY) {
        adjustmentDays = 2;
    }
    cal.add(Calendar.DAY_OF_MONTH, adjustmentDays);
    return cal.getTime();
}

private static SimpleDateFormat inputDateFormat = new SimpleDateFormat("yyyy-MM-dd");
private void txtStartKeyReleased(java.awt.event.KeyEvent evt) {
    try {
        txtExpiry.setText(
            inputDateFormat.format(
                addWeekdaysToDate(inputDateFormat.parse(txtStart.getText()), 102)
            )
        );
    } catch (ParseException ex) {
        Logger.getLogger(ClientInfo.class.getName()).log(Level.SEVERE, null, ex);
    } 
}