万年历方法二

import java.util.Scanner;
import javax.management.RuntimeErrorException;
public class PrintCalendar {
	public static void main(String[] args) {
		int month = 0;
		int day = 0;
		int sumdays = 0;
		int yearday = 0;
		int monthday = 0;
		int week = 0;
		int weekday = 0;
		String answer;
		Scanner sc = new Scanner(System.in);
		System.out.println("**************欢迎使用万年历************");
		System.out.println("请输入年份");
		int year = sc.nextInt();
		System.out.print("请输入月份:");
		month = sc.nextInt();

		//判断月份输入是否合法
		if (month <= 0 || month > 12) {
			throw new RuntimeErrorException(null, "月份输入错误");
		} else {
			boolean isRn = year % 4 == 0 && year % 100 != 0 || year % 400 == 0;   //判断是否为闰年
			//判断每一个月都有多少天
			if (month == 1 || month == 3 || month == 5 || month == 7
					|| month == 8 || month == 10 || month == 12) {
				day = 31;
			} else if (month == 4 || month == 6 || month == 9 || month == 11) {
				day = 30;
			} else if (month == 2 && isRn == true) {
				day = 29;
			} else {
				day = 28;
			}
			//1900年一月一日   周一
			//计算到当前年份的前一年一共有多少天
			for (int i = 1900; i < year; i++) {
				if (i % 4 == 0 && i % 100 != 0 || i % 400 == 0) {
					yearday = yearday + 366;
				} else {
					yearday = yearday + 365;
				}
			}
			//计算到当前月份的前一个月一共有多少天
			for (int n = 1; n < month; n++) {
				if (n == 1 || n == 3 || n == 5 || n == 7 || n == 8 || n == 10
						|| n == 12) {
					monthday = monthday + 31;
				} else if (n == 4 || n == 6 || n == 9 || n == 11) {
					monthday = monthday + 30;
				} else if (n == 2 && isRn == true) {
					monthday = monthday + 29;
				} else {
					monthday = monthday + 28;
				}
			}
			//System.out.println("1900年1月："+monthday);
			sumdays = yearday + monthday;
			//if(sumday%7!=0){
				week = 1 + sumdays % 7;
			//}else{
			//	week = sumdays%7
			//}
			System.out.println(week);
			System.out.println("日\t一\t二\t三\t四\t五\t六");
			if (week != 7) {
				for (int j = 0; j < week; j++) {
					System.out.print("\t");
				}
			}
			for (int k = 1; k <= day; k++) {
				weekday = (sumdays - 1 + k) % 7 + 1;
				if (weekday == 6) {
					System.out.print(k + "\n");
				} else {
					System.out.print(k + "\t");
				}
			}
		}
	}
}