在java中找到日子差异 [英] Finding days difference in java

问题描述

在咨询了几个论坛后，我最终使用下面的代码来查找日期差异。但是，我看到一个逻辑问题（可能是我的眼光？）。我看到，11到14和11到15之间的日差是一样的。如何可能？

After consulting a few forums, I ended up using the code below to find the days difference. But, I see a problem with the logic (may be it's my over sight?). I see that for days difference between 11 to 14 and 11 to 15 is same. How is it possible?

Date createdDate = new Date((2013 + 1900), (1 + 1), 11);
Date expirationDate = new Date((2013 + 1900), (1 + 1), 11);
for (int i = 11; i < 20; i++) {
    expirationDate.setDate(i);

    System.out.println("11 to " + i + " = "
            + (int) (expirationDate.getTime() - createdDate.getTime())
            / (1000 * 60 * 60 * 24));
}

输出是：

11 to 11 = 0
11 to 12 = 1
11 to 13 = 2
11 to 14 = 3
11 to 15 = 3
11 to 16 = 4
11 to 17 = 5
11 to 18 = 6
11 to 19 = 7

推荐答案

使用float，我看到问题。使用时间戳似乎并不是找到两个日期之间的差距的好方法。

Using float, I see the problem. Using timestamp doesn't seem like a good approach to finding the days difference between 2 dates.

11至11 = 0.0

11至12 = 1.0

11至13 = 2.0

11至14 = 3.0

11至15 = 3.9583333

11至16 = 4.9583335

11至17 = 5.9583335

11至18 = 6.9583335

11至19 = 7.9583335

11 to 11 = 0.0
11 to 12 = 1.0
11 to 13 = 2.0
11 to 14 = 3.0
11 to 15 = 3.9583333
11 to 16 = 4.9583335
11 to 17 = 5.9583335
11 to 18 = 6.9583335
11 to 19 = 7.9583335

展望未来，我发现确定日期差异的最确定方式为

Going forward, I find the most conclusive way to determine the date difference as

Calendar cre_calendar = new GregorianCalendar((2013), (1), 11);
        Calendar exp_calendar = new GregorianCalendar((2013), (1), 19);
        Calendar maxDays = new GregorianCalendar(((2013)), (12), 31);

        if (exp_calendar.get(Calendar.DAY_OF_YEAR) < cre_calendar
                .get(Calendar.DAY_OF_YEAR)) {
            System.out
                    .println((exp_calendar.get(Calendar.DAY_OF_YEAR) + maxDays
                            .get(Calendar.DAY_OF_YEAR))
                            - cre_calendar.get(Calendar.DAY_OF_YEAR));
        } else {
            System.out.println((exp_calendar.get(Calendar.DAY_OF_YEAR))
                    - cre_calendar.get(Calendar.DAY_OF_YEAR));
        }

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