如何计算2个日期之间的实际月数？ [英] How to calculate properly actual month count between 2 dates?

问题描述

我遵循方法 getDiffDateMap ，它计算2个日期之间的差异，并返回代表毫秒，秒的整数的 Map 分钟，小时，天，月和年。

I have followed method getDiffDateMap that calculates difference between 2 dates and returns Map of Integers that represent milliseconds, seconds, minutes, hours, days, months and years respectively.

public static Map<Integer, String> getDiffDateMap(String dateA, String dateB) {

    Calendar cal = Calendar.getInstance();      
    Map<Integer,String> out = new LinkedHashMap<Integer, String>();
    long timeInMillA = 0;
    long timeInMillB = 0;

    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 

    Date convertedDateA;
    Date convertedDateB;



    try {
        convertedDateA = dateFormat.parse(dateA);           
        cal.setTime(convertedDateA);
        timeInMillA = cal.getTimeInMillis();


        convertedDateB = dateFormat.parse(dateB);           
        cal.setTime(convertedDateB);
        timeInMillB = cal.getTimeInMillis();

    } catch (ParseException e) {
        e.printStackTrace();
    } 

    long mili = timeInMillB - timeInMillA;
    long sec = mili/1000;
    long min = sec/60;
    long hour = min/60;
    long day = hour/24;
    long week = day/7;
    long month = day/31; // ????
    long year = month/12;

    out.put(7, mili + "");
    out.put(6, sec + "");
    out.put(5, min + "");
    out.put(4, hour + "");
    out.put(3, day + "");
    out.put(2, week + "");
    out.put(1, month + "");
    out.put(0, year + "");

    return out;
}

我的问题是从实际日数计算月份：

My problem is to calculate month from actual day count:

long month = day/31; // or 30

例如：

Map<Integer,String> out = getDiffInMillsec("2012-9-01 20:9:01", "2012-10-01 20:10:01");

    System.out.println(Arrays.asList(out)); 

我得到输出： [{7 = 2592060000，6 = 2592060，5 = 43201,4 = 720,3 = 30,2 = 4,1 = 0,0 = 0}] 其中 1 是月数和因为差距只有30天。需要添加什么流程来解决这个问题？任何建议？

I get output: [{7=2592060000, 6=2592060, 5=43201, 4=720, 3=30, 2=4, 1=0, 0=0}] where 1 is month count and its 0. because difference is 30 days only. What flow need I add to fix this problem? Any suggestions?

推荐答案

我已经按照方法getDiffDateMap计算2个日期和返回的地图代表毫秒，秒，分，小时，天，月和年的整数。

I have followed method getDiffDateMap that calculates difference between 2 dates and returns Map of Integers that represent milliseconds, seconds, minutes, hours, days, months and years respectively.

不要重新发明轮：）

Joda时间有代码来做到这一切，更多。例如：

Joda Time has code to do all this and more. For example:

LocalDateTime start = ...;
LocalDateTime end = ...;
Period difference = new Period(start, end, PeriodType.yearMonthDayTime());
int months = difference.getMonths(); // etc

请注意，您不能几个月，当你刚刚将不同的转换为几毫秒 - 因为月数将取决于开始/结束日期。 （30天可能是或可能不是一个月，例如...）

Note that you can't get at the number of months when you've just converted the different to a number of milliseconds - as the number of months will depend on the start/end date. (30 days may or may not be a month, for example...)

我强烈建议您在整个Java代码中使用Joda Time，而不是 java.util。* 。这是一个更好的API，而且很有希望意味着你很少 - 甚至需要编写自己的日期/时间处理代码。

I'd strongly advise you to use Joda Time throughout your Java code, in preference to java.util.*. It's a much better API, and one which will hopefully mean you rarely-if-ever need to write your own date/time handling code.

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