用Java计算leap年

Question

这是家庭作业，我已经获得了成绩，但是我没有在代码中实现leap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。我唯一不知道的是一种实现implement年的方法，这种writing年将在2月获得29天而不是28天，而无需编写多条if语句。当然有更简单的方法吗？这是代码：

//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 \n"
                + "the number of days in a month based upon \n"
                + "your input, when prompted please enter \n"
                + "the numerical value of the month you would like\n"
                + "to view including the year. Example: if you would like\n"
                + "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");
        }
    }
}

Answer 1

如果使用GregorianCalendar，则可以执行以下操作

确定给定年份是否为is年。如果给定的年份是a年，则返回true。要指定BC年号，必须提供1年号。例如，BC 4年被指定为-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.");
}