在java中获取以天为单位的日期之间的差异
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getting the difference between date in days in java
提问by Charanraj Golla
Possible Duplicate:
how to calculate difference between two dates using java
可能的重复：
如何使用 java 计算两个日期之间的差异
I'm trying something like this, where I'm trying to get the date from comboboxes
我正在尝试这样的事情，我试图从组合框中获取日期
Calendar start = Calendar.getInstance();
Calendar end = Calendar.getInstance();
int Sdate=Integer.parseInt(cmbSdate.getSelectedItem().toString());
int Smonth=cmbSmonth.getSelectedIndex();
int Syear=Integer.parseInt(cmbSyear.getSelectedItem().toString());
int Edate=Integer.parseInt(cmbEdate.getSelectedItem().toString());
int Emonth=cmbEmonth.getSelectedIndex();
int Eyear=Integer.parseInt(cmbEyear.getSelectedItem().toString());
start.set(Syear,Smonth,Sdate);
end.set(Eyear,Emonth,Edate);
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
String startdate=dateFormat.format(start.getTime());
String enddate=dateFormat.format(end.getTime());
I'm not able to subtract the end and start date How do I get the difference between the start date and end date??
我无法减去结束日期和开始日期 如何获得开始日期和结束日期之间的差异？
采纳答案by hd42
Calendar start = Calendar.getInstance();
Calendar end = Calendar.getInstance();
start.set(2010, 7, 23);
end.set(2010, 8, 26);
Date startDate = start.getTime();
Date endDate = end.getTime();
long startTime = startDate.getTime();
long endTime = endDate.getTime();
long diffTime = endTime - startTime;
long diffDays = diffTime / (1000 * 60 * 60 * 24);
DateFormat dateFormat = DateFormat.getDateInstance();
System.out.println("The difference between "+
dateFormat.format(startDate)+" and "+
dateFormat.format(endDate)+" is "+
diffDays+" days.");
This will not work when crossing daylight savings time (or leap seconds) as orange80 pointed out and might as well not give the expected results when using different times of day. Using JodaTime might be easier for correct results, as the only correct way with plain Java before 8 I know is to use Calendar's add and before/after methods to check and adjust the calculation:
正如orange80所指出的那样，在跨越夏令时（或闰秒）时，这将不起作用，并且在使用一天中的不同时间时也可能不会给出预期的结果。使用 JodaTime 可能更容易获得正确的结果，因为我知道在 8 之前使用纯 Java 的唯一正确方法是使用 Calendar 的 add 和 before/after 方法来检查和调整计算：
start.add(Calendar.DAY_OF_MONTH, (int)diffDays);
while (start.before(end)) {
start.add(Calendar.DAY_OF_MONTH, 1);
diffDays++;
}
while (start.after(end)) {
start.add(Calendar.DAY_OF_MONTH, -1);
diffDays--;
}
回答by rics
Like this.
像这样。
import java.util.Date;
import java.util.GregorianCalendar;
/**
* DateDiff -- compute the difference between two dates.
*/
public class DateDiff {
public static void main(String[] av) {
/** The date at the end of the last century */
Date d1 = new GregorianCalendar(2000, 11, 31, 23, 59).getTime();
/** Today's date */
Date today = new Date();
// Get msec from each, and subtract.
long diff = today.getTime() - d1.getTime();
System.out.println("The 21st century (up to " + today + ") is "
+ (diff / (1000 * 60 * 60 * 24)) + " days old.");
}
}
}
Hereis an article on Java date arithmetic.
这是一篇关于 Java 日期算法的文章。
回答by Faisal Feroz
Use JodaTimefor this. It is much better than the standard Java DateTime Apis. Here is the code in JodaTime for calculating difference in days:
为此使用JodaTime。它比标准的 Java DateTime API 好得多。这是 JodaTime 中用于计算天数差异的代码：
private static void dateDiff() {
System.out.println("Calculate difference between two dates");
System.out.println("=================================================================");
DateTime startDate = new DateTime(2000, 1, 19, 0, 0, 0, 0);
DateTime endDate = new DateTime();
Days d = Days.daysBetween(startDate, endDate);
int days = d.getDays();
System.out.println(" Difference between " + endDate);
System.out.println(" and " + startDate + " is " + days + " days.");
}
