如何从java中减去当前日期的n天？

Question

我想在Java中减去当前日期的n天。

我该怎么做？

Answer 1

您不必使用日历。你可以玩时间戳：

Date d = initDate();//intialize your date to any date 
Date dateBefore = new Date(d.getTime() - n * 24 * 3600 * 1000 l ); //Subtract n days   

<强>更新 不要忘记在1000年底之前长期添加“l”。

请考虑以下警告：

在闰秒，夏令时等情况下，将1000*60*60*24毫秒添加到java日期将在很长一段时间内向原始日期添加零天或两天。如果您需要100％确定只添加一天，则此解决方案不是使用的解决方案。

Answer 2

这将减去当前日期的十天（在Java 8之前）：

int x = -10;
Calendar cal = GregorianCalendar.getInstance();
cal.add( Calendar.DAY_OF_YEAR, x);
Date tenDaysAgo = cal.getTime();

如果您使用的是Java 8，则可以使用新的日期和版本。时间API（http://www.oracle.com/technetwork/articles/java/jf14-date-time-2125367.html）：

LocalDate tenDaysAgo = LocalDate.now().minusDays(10);

要将新版本转换为旧版本，反之亦然，请参阅：Converting between java.time.LocalDateTime and java.util.Date

Answer 3

我找到了这个完美的解决方案并且可能很有用，您可以根据需要直接获取格式：

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -90); // I just want date before 90 days. you can give that you want.

SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd"); // you can specify your format here...
Log.d("DATE","Date before 90 Days: " + s.format(new Date(cal.getTimeInMillis())));

感谢。

Answer 4

供将来使用查找星期几，扣除日期并使用日期显示扣除的日期。

public static void main(String args[]) throws ParseException {

String[] days = { "Sunday", "Monday", "Tuesday", "Wednesday",
        "Thursday", "Friday", "Saturday" };
SimpleDateFormat format1 = new SimpleDateFormat("dd/MM/yyyy");
Date dt1 = format1.parse("20/10/2013");

Calendar c = Calendar.getInstance();
c.setTime(dt1);
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK);
long diff = Calendar.getInstance().getTime().getTime() ;
System.out.println(dayOfWeek);

switch (dayOfWeek) {

case 6:
    System.out.println(days[dayOfWeek - 1]);
    break;
case 5:

    System.out.println(days[dayOfWeek - 1]);
    break;      
case 4:
    System.out.println(days[dayOfWeek - 1]);
    break;
case 3:

    System.out.println(days[dayOfWeek - 1]);
    break;
case 2:
    System.out.println(days[dayOfWeek - 1]);
    break;
case 1:

    System.out.println(days[dayOfWeek - 1]);

     diff = diff -(dt1.getTime()- 3 );
     long valuebefore = dt1.getTime();
     long valueafetr = dt1.getTime()-2;
     System.out.println("DATE IS befor subtraction :"+valuebefore);
     System.out.println("DATE IS after subtraction :"+valueafetr);

     long x= dt1.getTime()-(2 * 24 * 3600 * 1000);
     System.out.println("Deducted date to find firday is - 2 days form Sunday :"+new Date((dt1.getTime()-(2*24*3600*1000))));
     System.out.println("DIffrence from now on is :"+diff);
        if(diff > 0) {

            diff = diff / (1000 * 60 * 60 * 24);
            System.out.println("Diff"+diff);
            System.out.println("Date is Expired!"+(dt1.getTime() -(long)2));
        }

    break;
}
}

Answer 5

正如@Houcem Berrayana所说

如果您想使用n>24，则可以使用以下代码：

Date dateBefore = new Date((d.getTime() - n * 24 * 3600 * 1000) - n * 24 * 3600 * 1000); 

假设您要查找最近30天的日期，那么您将使用：

Date dateBefore = new Date((d.getTime() - 24 * 24 * 3600 * 1000) - 6 * 24 * 3600 * 1000);