用Java计算闰年 [英] Calculate leap year in Java

问题描述

可能重复:
计算闰年的Java代码，这段代码正确吗?

这是作业，我已经收到了成绩，但我没有在我的代码中实现闰年.这是一个简单的程序，可以根据用户输入显示一个月内的数字.唯一的事情是我想不出一种方法来实现闰年，2 月将获得 29 天而不是 28 天，而无需编写多个 if 语句.当然有更简单的方法吗?代码如下:

This was homework, and I have already received my grade, but I did not implement leap years in my code. This is a simple program that displays the numbers in a month based on user input. The only thing is I can't figure out is a way to implement a leap year that would get 29 days for February rather than 28, without writing multiple if statements. Surely there is an easier way? Here is the code:

//Displays number of days in a month

package chapter_3;

import java.util.Scanner;


public class Chapter_3 {

    public static void main(String[] args) {
        System.out.println("This program will calculate 
"
                + "the number of days in a month based upon 
"
                + "your input, when prompted please enter 
"
                + "the numerical value of the month you would like
"
                + "to view including the year. Example: if you would like
"
                + "to view March enter 3 2011 and so on.");

        Scanner input = new Scanner(System.in);

        //Prompt user for month and year
        System.out.print("Please enter the month and year: ");
        int month = input.nextInt();
        int year = input.nextInt();

        if (month == 1) {
            System.out.println("January " + year + " has 31 days");
        }   
        else if (month == 2) {
            System.out.println("February " + year + " has 28 days");
        }   
        else if (month == 3) {
            System.out.println("March " + year + " has 31 days");
        }
        else if (month == 4) {
            System.out.println("April " + year + " has 30 days");
        }
        else if (month == 5) {
            System.out.println("May " + year + " has 31 days");
        }
        else if (month == 6) {
            System.out.println("June " + year + " has 30 days");
        }
        else if (month == 7) {
            System.out.println("July " + year + " has 31 days");
        }
        else if (month == 8) {
            System.out.println("August " + year + " has 31 days");
        }
        else if (month == 9) {
            System.out.println("September " + year + " has 30 days");
         }
        else if (month == 10) {
            System.out.println("October " + year + " has 30 days");
        }
        else if (month == 11) {
            System.out.println("November " + year + " has 30 days");
        }
        else if (month == 12) {
            System.out.println("December " + year + " has 31 days");
         }
        else {
            System.out.println("Please enter the numerical value "
                + "of the month you would like to view");
        }
    }
}        

推荐答案

如果你使用 GregorianCalendar，你可以这样做

If you use the GregorianCalendar, you could do as below

确定给定年份是否为闰年.如果给定，则返回 true年是闰年.要指定 BC 年编号，必须使用 1 年编号被给予.例如，公元前 4 年指定为 -3.

Determines if the given year is a leap year. Returns true if the given year is a leap year. To specify BC year numbers, 1 - year number must be given. For example, year BC 4 is specified as -3.

GregorianCalendar cal = new GregorianCalendar();

if(cal.isLeapYear(year))
{
    System.out.print("Given year is leap year.");
}
else
{ 
    System.out.print("Given year is not leap year.");
}

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