我正在寻找一个计算两个日期之间的月份的解决方案。我认为joda或java8时间可以做到。但是当我比较它们时，我发现了一些非常奇怪的东西。

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.time.LocalDateTime;

import java.time.ZoneId;

import java.time.temporal.ChronoUnit;

import java.util.Date;

import org.joda.time.Months;

public class DateMain {

public static void main(String[] args) throws ParseException {

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");

Date d1 = simpleDateFormat.parse("2017-01-28 00:00:00.000");

Date d2 = simpleDateFormat.parse("2017-02-28 00:00:00.000");

System.out.println("Test Cast 1");

System.out.println("joda time api result: " + monthsBetweenJoda(d1, d2) + " month");

System.out.println("java8 time api result: " + monthsBetweenJava8(d1, d2) + " month");

Date dd1 = simpleDateFormat.parse("2017-01-29 00:00:00.000");

Date dd2 = simpleDateFormat.parse("2017-02-28 00:00:00.000");

System.out.println("Test Cast 2");

System.out.println("joda time api result: " + monthsBetweenJoda(dd1, dd2) + " month");

System.out.println("java8 time api result: " + monthsBetweenJava8(dd1, dd2) + " month");

}

public static int monthsBetweenJoda(Date fromDate, Date toDate) {

if (fromDate == null || toDate == null) {

throw new IllegalArgumentException();

}

org.joda.time.LocalDateTime fromLocalDateTime = org.joda.time.LocalDateTime

.fromDateFields(fromDate);

org.joda.time.LocalDateTime toLocalDateTime = org.joda.time.LocalDateTime

.fromDateFields(toDate);

Months months = Months.monthsBetween(fromLocalDateTime, toLocalDateTime);

return months.getMonths();

}

public static long monthsBetweenJava8(Date fromDate, Date toDate) {

if (fromDate == null || toDate == null) {

throw new IllegalArgumentException();

}

LocalDateTime ldt1 = fromDate.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();

LocalDateTime ldt2 = toDate.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();

return ChronoUnit.MONTHS.between(ldt1, ldt2);

}

}

输出如下：

Test Cast 1

joda time api result: 1 month

java8 time api result: 1 month

Test Cast 2

joda time api result: 1 month

java8 time api result: 0 month

我对测试用例2感到非常困惑，哪一个合理？

对不起，这是我的第一个问题。已完成的代码已附加。