java.util.Date计算差异天数 [英] java.util.Date Calculate difference in days

问题描述

我试图计算两个日期之间的差异，我注意到一件事。在计算天数时，夏令时间的开始时间将包含在间隔内，所以结果将在1天内缩短。

为了获得准确的结果，

例如：

  SimpleDateFormat format = new SimpleDateFormat（MM-dd-yyyy）; 
日期dfrom = format.parse（03-29-2015）; 
日期dto = format.parse（03-30-2015）; 
 long diff = dto.getTime（） -  dfrom.getTime（）; 
 System.out.println（diff）; 
 System.out.println（Days：+ diff /（24 * 60 * 60 * 1000））; 
 System.out.println（Hours：+ diff /（60 * 60 * 1000）％24）; 
  

输出：

 code> 82800000 
日期：0 
营业时间：23 
  

任何人有更好的解决方案？

解决方案

哦，是一个更好的解决方案！

停止使用过时的 java.util.Date 类，并拥抱 java.time API 内置到Java 8和更高版本（教程）。具体来说， DateTimeFormatter ， LocalDate 和 ChronoUnit 课程。

  DateTimeFormatter formatter = DateTimeFormatter.ofPattern（MM-dd-yyyy）; 
 LocalDate date1 = LocalDate.parse（03-29-2015，formatter）; 
 LocalDate date2 = LocalDate.parse（03-30-2015，formatter）; 
 long days = ChronoUnit.DAYS.between（date1，date2）; 
 System.out.println（days）; //打印1 
  

I tried to calculate the difference between two dates and I noticed one thing. When calculating only the days, the start of daylight saving time is included in the interval, so the result will be shorter with 1 day.

To obtain accurate results, the value of hours also must be considered.

For example:

SimpleDateFormat format = new SimpleDateFormat("MM-dd-yyyy");
Date dfrom = format.parse("03-29-2015");
Date dto = format.parse("03-30-2015");
long diff = dto.getTime() - dfrom.getTime();
System.out.println(diff);
System.out.println("Days: "+diff / (24 * 60 * 60 * 1000));
System.out.println("Hours: "+diff / (60 * 60 * 1000) % 24);

Output:

82800000
Days: 0
Hours: 23

Does anybody have a better solution?

解决方案

Oh yes a better solution there is!

Stop using the outmoded java.util.Date class and embrace the power of the java.time API built into Java 8 and later (tutorial). Specifically, the DateTimeFormatter, LocalDate, and ChronoUnit classes.

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM-dd-yyyy");
LocalDate date1 = LocalDate.parse("03-29-2015", formatter);
LocalDate date2 = LocalDate.parse("03-30-2015", formatter);
long days = ChronoUnit.DAYS.between(date1, date2);
System.out.println(days); // prints 1

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