import java.util.Scanner;
import java.util.InputMismatchException;
public class date {
public static int t1; //integers for methods
public static int t2;
public static int x = 0; //integer for looping
public static int y1;
public static int m1;
public static int d1;
public static int y2;
public static int m2;
public static int d2;
public static void date1() {
do //along with "while" statement. Makes loop if error occurs
{
Scanner scanner = new Scanner(System.in);
try { // try (run program as normal)
System.out.println("Please enter the first date ");
System.out.println("Please enter the year: "); //entering date
y1 = scanner.nextInt();
System.out.println("Please enter the month: ");
m1 = scanner.nextInt();
System.out.println("Please enter the day: ");
d1 = scanner.nextInt();
break; // break loop if input is correct
} catch (InputMismatchException inputMismatchException) { // response to "Try". if input is incorrect error will be displayed
scanner.nextLine();
System.err.println("You must enter intergers. Please try again. ");
}
x = x + 1 ; // set loop to three attempts
} while (x < 3) ; //do process occurs while attempts are under < 4
}
public static void caldate1() {
do //along with "while" statement. Makes loop if error occurs
{
int j = 693502;
try {
if (m1 == 1 || m1 == 3 || m1 == 5 || m1 == 7 || m1 == 8 || m1 == 10 // if/else statements to set proper numbers of days in each month
|| m1 == 12) {
t1 = ((365 * y1) + d1 + 31);
} else if (m1 == 2) {
t1 = ((365 * y1) + d1 + 28);
} else if (m1 == 4 || m1 == 6 || m1 == 9 || m1 == 11) {
t1 = ((365 * y1) + d1 + 30);
}
if (t1 >= j) //if/else statement to catch error if date inputted isnt over jan 1st 1900
{ break;} // break loop if date is greater or equal to jan 1st 1900
else {
System.err.printf("Please enter a date after Jan 1st 1900.\n");
}
} catch (InputMismatchException inputMismatchException) { //error if date too small
System.err.println("You must enter intergers. Please try again. ");
}
x = x + 1 ; // set loop to three attempts
} while (x < 3) ;
}
public static void date2() {
do // process to follow if length == 5
{
Scanner scanner = new Scanner(System.in);
try { // try (run program as normal)
System.out.println("Please enter the second date ");
System.out.println("Please enter the year: "); // entering second date
y2 = scanner.nextInt();
System.out.println("Please enter the month: ");
m2 = scanner.nextInt();
System.out.println("Please enter the day: ");
d2 = scanner.nextInt();
break; // break loop if input is correct
} catch (InputMismatchException inputMismatchException) { // response to "try". if input is incorrect error will be displayed
scanner.nextLine();
System.err.println("You must enter intergers. Please try again. ");
}
x = x + 1 ; // set loop to three attempts
} while (x < 3) ; //do process occurs while attempts are under < 4
}
public static void caldate2() {
do //all code is same as in caldate1()... just second set of variables.
{
int j = 693502;
try {
if (m2 == 1 || m2 == 3 || m2 == 5 || m2 == 7 || m2 == 8 || m2 == 10
|| m2 == 12) {
t2 = ((365 * y2) + d2 + 31);
} else if (m2 == 2) {
t2 = ((365 * y2) + d2 + 28);
} else if (m2 == 4 || m2 == 6 || m2 == 9 || m2 == 11) {
t2 = ((365 * y2) + d2 + 30);
}
if (t2 >= j)
{ break;}
else {
System.err.printf("Please enter a date after Jan 1st 1900.\n");
}
} catch (InputMismatchException inputMismatchException) {
System.err.println("You must enter intergers. Please try again. ");
}
x = x + 1 ; // set loop to three attempts
} while (x < 3) ;
}
public static void finaldate1() {
x = Math.abs(t1 - t2); //calculate total day difference. output absolute value so that result is always positive
System.out.println("The difference between the two dates is: " + x + " days.");
}
public static void main(String[] args) {
date1();
caldate1();
date2();
caldate2();
finaldate1();
}
}
比如说你输入2011年2月28日和2011年3月1日。 天数应为1.但它计算24.任何人都知道问题是什么？因为当我输入其他日期时，计算日期就好了。
答案 0 :(得分：1)
呀。不要那样做。创建两个GregorianCalendar类，将两者转换为毫秒并减去以找出差异。然后转换回几天。
确保你看月份，因为GregorianCalendar愚蠢地基于0。
答案 1 :(得分：0)
尝试将此修改为您的算法。我有一系列的int代表每个月的天数。然后，如果您正在查看二月（月== 2），那么您可以将数组中第二个元素之前的所有值添加到总数（t）。我还通过添加参数来重构该方法，因为您的设计目前很丑陋（您必须执行完全相同的功能，但写入两次）。
编辑：我假设月份在输入时被编入索引0。如果不是，则在将其传递给此方法之前从中减去1。
public static int months[] = new int {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
//Note Im assuming error checking has already been done on the data (especially month)
public static int caldate(int year, int month, int day)
{
int t = 0;
t += year * 365; // assume no leap years
for(int i = 0; i < month && i < 12; i++)
{
t += months[i];
}
t += day;
return t;
}
答案 2 :(得分：-1)
我建议使用joda时间。它可以让您在没有太多麻烦的情况下对日期进行简单的数学计算，并计算从1到12的月份。
DateMidnight dm1 = new DateMidnight(y1, m1, d1);
DateMidnight dm2 = new DateMidnight(y2, m2, d2);
Days days = Days.daysBetween(dm1, dm2);
int dayCount = days.getDays();