查找Java中的天差

Question

在咨询了几个论坛之后，我最终使用下面的代码来查找时间差异。但是，我发现逻辑上存在问题（可能是我的视线吗？）。我看到11到14天和11到15天之间的差异是相同的。这怎么可能？

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));
}

输出为：

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

Answer 1

使用浮动，我看到了问题。使用时间戳似乎不是找到两个日期之间的天差的好方法。

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

展望未来，我发现确定日期差异的最确定的方法是

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));
        }