Java language programming：日历打印

题目：设计一个日历的程序
输入格式：
请输入年份：
2022
请输入月份：
1

输出格式：
这个月的第一天是：6
一 二 三 四 五 六 日
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入年份：");
        int year = input.nextInt();
        System.out.println("请输入月份：");
        int month = input.nextInt();
        int days = 0;
        for (int i = 1900; i < year; i++) {
            if (i % 4 == 0 && i % 100 != 0 || i % 400 == 0) {
                days += 366;
            }else{
                days += 365;
            }
        }
        for (int i = 1; i < month; i++) {
            if (i == 2) {
                if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
                    days += 29;
                }
            } else if (i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12) {
                days += 31;
            } else {
                days += 30;
            }

        }
        int week = 1 + days % 7;
        System.out.println("这个月的第一天是：" + week);
        System.out.println("一\t二\t三\t四\t五\t六\t日\t");
        for (int i = 1; i < week; i++) {
            System.out.print("\t");
        }
        int damon = 0;
        switch (month) {
            case 2:
                if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
                    damon = 29;
                } else {
                    damon = 28;
                }
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                damon = 30;
                break;
            default:
                damon = 31;
                break;
        }
        for (int i = 1; i <= damon; i++) {
            System.out.print(i + " \t");
            if ((week - 1 + i) % 7 == 0) {
                System.out.println();
            }

        }
    }

}