Java制作万年历

import java.util.*;

 

public class CalcDate {
     int year;
     int month;
     int day;
 
public void Input(){//输入方法

    Scanner input = new Scanner(System.in);
    boolean flag = true;//控制检查日期格式输入是否正确的循环
    String date = "";//日期

    while(flag){
       System.out.print("请输入年,月，日(yyyy-mm-dd):");
       date = input.next();
       if(date.indexOf('-') != 4 && date.lastIndexOf('-') != 7){//判断日期格式
        System.out.println("日期格式输入错误！");
       }else{
        flag = false;
       }
    }
      String[] dateArr = date.split("-");//将日期字符串分割成年月日
      year = Integer.parseInt(dateArr[0]);
      month = Integer.parseInt(dateArr[1]);
      day = Integer.parseInt(dateArr[2]);
      
      int result = Calc(year,month,day);//计算
      switch(result){
      case 0:
       System.out.println("此日期是星期日");
       break;
      case 1:
       System.out.println("此日期是星期一");
           break;
      case 2:
       System.out.println("此日期是星期二");
       break;
      case 3:
       System.out.println("此日期是星期三");
       break;
      case 4:
       System.out.println("此日期是星期四");
       break;
      case 5:
       System.out.println("此日期是星期五");
       break;
      case 6:
       System.out.println("此日期是星期六");
       break;
      default://异常
       System.out.println("未知错误，程序中断！");
       break;
      }

}
 
 public void ShowCalendar(){
  int days = 30;
  switch(month){//本月天数
  case 1:
   days = 31;
   break;
  case 2:
   if(IsLeapYear(year)){//闰年
    days = 29;
   }else{
    days = 28;
   }
   break;
  case 3:
   days = 31;
   break;
  case 4:
   days = 30;
   break;
  case 5:
   days = 31;
   break;
  case 6:
   days = 30;
   break;
  case 7:
   days = 31;
   break;
  case 8:
   days = 31;
   break;
  case 9:
   days = 30;
   break;
  case 10:
   days = 31;
   break;
  case 11:
   days = 30;
   break;
  case 12:
   days = 31;
   break;
  default://异常
   System.out.println("未知错误");
   break;
  }
  System.out.println("本月日历为\n日\t一\t二\t三\t四\t五\t六");//显示日历
  int first = Calc(year,month,1);//获取本月一号是星期几
  for(int i = 0;i < first;i++){//控制本月一号之前的空格数
   System.out.print("  \t");
  }
  int j = 1;//本月一号
  for(j = 1;j <= 7-first;j++){//第一行
   System.out.print(j+"\t");
  }
  System.out.println();
  while(j<days){//余下几行
   int times = j+7;
   for(;j<times;j++){
    if(j>days){
     break;
    }
    System.out.print(j+"\t");
   }
   System.out.println();
  }
 }
 
 public int Calc(int y,int m,int d){//计算方法
  if(m == 1 || m == 2){//如果月份为一月或2月，则看成上一年的十三月和十四月
   m += 12;
   y--;
  }
  return (int)((d+2*m+3*(m+1)/5+y+y/4-y/100+y/400)+1)%7;//代入基尔拉姆森公式
 }
 
 public boolean IsLeapYear(int y){//判断是否为闰年
  if((y % 400 == 0) ||(y % 100 != 0)&&(y % 4 ==0)){
   return true;
  }else{
   return false;
  }
 }
 
 public static void main(String[] args) {
  CalcDate t = newCalcDate();
  Scanner input = new Scanner(System.in);
  String con = "";
  while(true){
   t.Input();
   t.ShowCalendar();
   System.out.print("继续吗？（Y/N）");
   con = input.next();
   if(con.equalsIgnoreCase("Y")){
    continue;
   }
   break;
  }
  System.out.println("程序结束，谢谢使用！");
 }
}

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