计算两个Java日历之间的差异

Question

我试图从两个日历的差异中获得时间，并知道结果是否超过一天（86400secs）。问题是有时我会得到很大的负值。

private long calcValidityDuration(XMLGregorianCalendar greg, XMLGregorianCalendar gregStart) {


        int minEnd = greg.getMinute();
        int minStart = gregStart.getMinute();
        int hourStart = gregStart.getHour();
        int hourEnd = greg.getHour();
        int dayEnd = greg.getDay();
        int dayStart = gregStart.getDay();
        int monthStart = gregStart.getMonth();
        int monthEnd = greg.getMonth();
        int yearStart = gregStart.getYear();
        int yearEnd = greg.getYear();

        Calendar cal = new GregorianCalendar();
        cal.set(yearEnd, monthEnd - 1, dayEnd, hourEnd, minEnd);
        Calendar calStart = new GregorianCalendar();
        calStart.set(yearStart, monthStart - 1, dayStart, hourStart, minStart);
        long toRet = (((cal.getTimeInMillis()) - (calStart.getTimeInMillis())) / 1000);
        if(toRet >= 86400){
            return 86400;
        }else{
            return toRet;
        }
}

这里有一些有问题的日期：

开课日期：30/09/16 07 截止日期：29/09/16 16

开课日期：29/09/16 16 截止日期：29/09/16 16

开课日期：08/09/16 08 截止日期：29/09/16 16

开课日期：29/09/16 16 截止日期：21/11/14 19

开课日期：29/09/16 16 截止日期：2014年3月20日13

Answer 1

public static long getDistanceDay(Calendar one,Calendar two) {

    long time1 = one.getTimeMillis();
    long time2 = two.getTImeMillis();
    long time;

    if(time1 > time2) {
        time = time-time2;
    }
    else {
        time = time2 - time1;
    }
    return time/(1000*60*60*24)
}