编写一个java方法，返回两个给定日期的相差天数

编写一个java方法，返回两个给定日期的相差天数

import java.util.*;
public class MyDate{
int day;
int month;
int year;
public MyDate(){}
public MyDate(int day,int month,int year){
this.day = day;
this.month = month;
this.year = year;
}
public void funtion(MyDate d){
int newDay = d.day;
int newMonth = d.month;
int newYear = d.year;
Calendar c1 = Calendar.getInstance();
c1.set(newYear,newMonth,newDay);
long n1 = c1.getTimeInMillis();
Calendar c2 = Calendar.getInstance();
c2.set(year,month,day);
long n2 = c2.getTimeInMillis();
System.out.println( "相差天数为:" + Math.abs((n1 - n2)/24/3600000)); }
public static void main(String[] args){
MyDate d1 = new MyDate(1,1,2008);
MyDate d2 = new MyDate(2,1,2001);
d1.funtion(d2);
}
}2016-05-24

class MyDate { public int year; public int month; public int day; public MyDate(int year, int month, int day) { super(); this.year = year; this.month = month; this.day = day; }}public class CalculateDays { /** * 判断该年份是不是闰年 * * @param year * 年份 */ public static boolean isLeapYear(int year) { return year % 4 == 0 && (year % 400 == 0 || year % 100 != 0); } /** * 计算月份有多少天 * * @param year * 年 * @param month * 月份 */ public static int getDaysOfMonth(int year, int month) { if (month == 2) { return isLeapYear(year) ? 29 : 28; } if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) { return 31; } else { return 30; } } /** * 计算两个日期之间的天数 * * @param start * 开始日期 * @param end * 结束日期 */ public static long calculate(MyDate start, MyDate end) { long sum = 0; int startYear = start.year; int endYear = end.year; int startMonth = start.month; int endMonth = end.month; int subMonthDays = 0; for (int yearIndex = startYear; yearIndex < endYear; yearIndex++) { sum += 365; if (isLeapYear(yearIndex)) { sum += 1; } } for (int monthIndex = 1; monthIndex < endMonth; monthIndex++) { sum += getDaysOfMonth(endYear, monthIndex); } for (int monthIndex = 1; monthIndex < startMonth; monthIndex++) { subMonthDays += getDaysOfMonth(startYear, monthIndex); } return sum + end.day - subMonthDays - start.day; } public static void main(String[] args) { MyDate start = new MyDate(2015, 5, 23); MyDate end = new MyDate(2015, 5, 27); System.out.println(calculate(start, end)); }}2016-05-24

Calendar c1 = Calendar.getInstance();Calendar c2 = Calendar.getInstance();c1.set(2015, 4, 29);c2.set(2015, 5, 20);long lna = c2.getTimeInMillis() - c1.getTimeInMillis();int na = (int) lna / (1000*3600*24); // 毫秒转换为天System.out.println(na);大概这个样子吧
如果需要的功能并不复杂，或者对效率要求比较高，可以自己写一个，java给的是 Calendar
2016-05-24