JAVA实现的简单万年历代码

import java.util.Scanner;
public class PrintCalendar {
 public static void main(String[] args) {
 int years = 0;
 int month = 0;
 int days = 0; 
 boolean isRun = false;
 //?目刂铺ㄝ?入年，月
 Scanner input = new Scanner(System.in);
 System.out.print("??入年份：");
 years = input.nextInt();
 System.out.print("??入月份：");
 month = input.nextInt();
 System.out.println("\n*********"+years+"年"+month+"月 日?驯?************");
 //判断是否是闰年
 if((years % 4 == 0 && years % 100 != 0) || (years % 400 == 0)){
 isRun = true;
 }
 int totalDays = 0; //累?天??
 //?算距?x1900年1月1日的天??
 for(int i = 1900; i < years; i++){
 if((i % 4 == 0 && i % 100 != 0) || (i % 400 == 0)){
 totalDays = totalDays + 366;
 }else{
 totalDays = totalDays + 365;
 }
 }
 int beforeDays = 0;
 //根??月份判?嗵??
 for(int j = 1; j <= month; j++){
 switch(j){
 case 1:
 case 3:
 case 5:
 case 7:
 case 8:
 case 10:
 case 12:
 days = 31;
 break;
 case 4:
 case 6:
 case 9:
 case 11:
 days = 30;
 break;
 case 2:
 if(isRun){
  days = 29;
 }else{
  days = 28;
 }
 default:
 System.out.println("输入月份不正确!!");
 }
 if(j < month){
 beforeDays = beforeDays + days;
 }
 }
 totalDays = totalDays + beforeDays; //?y?到目前?天??
 int firstDayOfMonth = 0;
 int temp = 1 + totalDays % 7 ;
 if(temp == 7){
 firstDayOfMonth = 0; //?L日
 }else{
 firstDayOfMonth = temp;
 }
 /* 输出日历 */
 System.out.println("星期日\t星期一\t星期二\t星期三\t星期四\t星期五\t星期六");
 for(int k = 0; k < firstDayOfMonth; k++){
 System.out.print("\t");
 }
 for(int m = 1; m <= days; m++){
 System.out.print( m + "\t");
 if((totalDays + m) % 7 == 6){
 System.out.print("\n");
 }
 }
 }
}