日期差异 java 执行错误 output

Question

我目前正在做一个日期差异 function 并且在这种情况下，我没有为闰年添加 function 但它倾向于我，即使不是闰年的日期差异 Z78E6221F6393D14566881ZD 与实际 DB39 不同天数取决于日期。

import java.util.Scanner;

public class Date_Difference {

    public static void main(String[] args) {
        Scanner myObj = new Scanner(System.in);     
        int d1 = myObj.nextInt();
        int m1 = myObj.nextInt();
        int y1 = myObj.nextInt();
        int d2 = myObj.nextInt();
        int m2 = myObj.nextInt();
        int y2 = myObj.nextInt();
        System.out.println(get_Difference(d1,m1,y1,d2,m2,y2));
    }

    static int get_Difference(int d1, int m1, int y1, int d2, int m2, int y2 ) { 
        int n1 = y1 * 365 + d1; 
        int i;
        for (i = 0; i < m1 - 1; i++) { 
            n1 += monthDays_notleapyear[i]; 
        } 
        int n2 = y2 * 365 + d2; 
        for (i = 0; i < m2 - 1; i++) { 
            n2 += monthDays_notleapyear[i]; 
        } 
        return Math.abs(n2 - n1); 
    } 
     static int monthDays_notleapyear[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; 
}

输入：d1=22 12 1999 d2=31 01 2019 output：6975 天实际 output：6980 天

Answer 1

选项1：

如果你可以使用 Java 日期 API 和 Java 8，你可以很容易地做到这一点。

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

public class Date_Difference {

    public static void main(String[] args) {

        long daysBetween = ChronoUnit.DAYS.between(LocalDate.of(1999, 12, 22), LocalDate.of(2019, 01, 31));

        System.out.println(daysBetween);

    }

}

选项 2：如果您不应该使用 Java 日期 API，那么下面是一种间接计算方式。

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.Scanner;

public class FSD {

    static int monthDays_notleapyear[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

    public static void main(String[] args) {
        Scanner myObj = new Scanner(System.in);
        int d1 = myObj.nextInt();
        int m1 = myObj.nextInt();
        int y1 = myObj.nextInt();
        int d2 = myObj.nextInt();
        int m2 = myObj.nextInt();
        int y2 = myObj.nextInt();

        long daysBetween = ChronoUnit.DAYS.between(LocalDate.of(y1, m1, d1), LocalDate.of(y2, m2, d2));

        System.out.println("Using Java Date: " + daysBetween);
        get_Difference(d1, m1, y1, d2, m2, y2);
    }

    static int get_Difference(int d1, int m1, int y1, int d2, int m2, int y2) {
        // int n1 = y1 * 365 + d1;

        int yearDiff = y2 - y1 - 1;

        int totalDays = yearDiff * 365;

        int numberOfLeapDays = numberOfLeapYearBetween(y1, y2);

        // Check if (m1 == 2 and d1 <=29 ) or if m1 == 1, increment by 1.
        if ((m1 <= 2 && d1 <= 29) || m1 == 1) {

            boolean isStartLeapYear = isLeapYear(y1);
            if (isStartLeapYear) {
                numberOfLeapDays++;
            }
        }

        // Check if m2 is greater than 3. If yes, check if leap year, increment by 1.
        if (m2 >= 3) {
            boolean isEndLeapYear = isLeapYear(y2);
            if (isEndLeapYear) {
                numberOfLeapDays++;
            }
        }

        int remainingDays = 0;
        for (int i = m1; i <= 12; i++) {

            if (i == m1) {
                remainingDays = remainingDays + (monthDays_notleapyear[i - 1] - d1);
            } else {

                remainingDays = remainingDays + monthDays_notleapyear[i - 1];
            }
        }

        for (int i = m2; i > 0; i--) {
            if (i == m2) {
                remainingDays = remainingDays + d2;
            } else {
                remainingDays = remainingDays + monthDays_notleapyear[i - 1];
            }
        }

        totalDays = totalDays + numberOfLeapDays + remainingDays;

        System.out.println("Total Days: " + totalDays);

        return totalDays;
    }

    private static boolean isLeapYear(int year) {

        boolean leap = false;

        if (year % 4 == 0) {
            if (year % 100 == 0) {
                // year is divisible by 400, hence the year is a leap year
                if (year % 400 == 0)
                    leap = true;
                else
                    leap = false;
            } else
                leap = true;
        } else
            leap = false;

        return leap;

    }

    /**
     * Get Number of Leap Years excluding startYear and endYear.
     * 
     * @param startYear
     * @param endYear
     * @return
     */
    private static int numberOfLeapYearBetween(int startYear, int endYear) {

        int counter = 0;
        while (startYear < endYear - 1) {
            startYear++;
            boolean isLeapYear = isLeapYear(startYear);
            if (isLeapYear) {
                counter++;
            }
        }
        return counter;

    }

}