Java打印万年历

import java.util.Scanner;

/*
* 星期计算公式
* yearDays = getYearDays(year, month, day);
* week = (year-1+(year-1)/4-(year-1)/100+(year-1)/400+yearDays)%7;
*/
public class Print_Calendar {

    public static void main(String[] args) {
        System.out.println("请输入日期（格式为yyyy-mm）:");
        Scanner input = new Scanner(System.in);
        String line = input.nextLine();
        int year = Integer.parseInt(line.split("-")[0]);
        int month = Integer.parseInt(line.split("-")[1]);
        print_Calendar(year,month);
    }

    //打印日历
    private static void print_Calendar(int year, int month) {
        System.out.println("一\t二\t三\t四\t五\t六\t日\t");
        int count = 0;
        for (int i = 1; i < getWeek(year,month,1); i++) {
            System.out.print("\t");
            count ++;
        }
        for (int i = 1; i <= getMonthdays(year,month); i++) {
            System.out.print(i+"\t");
            count ++;
            if(count%7 == 0)
                System.out.println();
        }
    }

    //计算星期
    private static int getWeek(int year,int month,int day) {
        int week = 0;
        int yearDays = 0;
        yearDays = getYeardays(year,month,day);
        week = (year-1+(year-1)/4-(year-1)/100+(year-1)/400+yearDays)%7;
        return week==0 ? 7 : week;
    }

    //计算当前日期在这一年有多少天
    private static int getYeardays(int year,int month,int day) {
        int days = 0;
        for (int i = 1; i < month; i++) {
            days = days + getMonthdays(year,i);
        }
        days = days + day;
        return days;
    }

    //计算一个月有多少天
    private static int getMonthdays(int year,int month) {
        int day = 0;
        switch (month){
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                day = 31;
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                day = 30;
                break;
            case 2:
                if((year%4==0 && year%100!=0) || year%400==0)
                    day = 29;
                else
                    day = 28;
                break;
        }
        return day;
    }

}