//本程序可實現
//功能1：計算當前日期向后或向前數日的日期
//功能2：計算當前日期和特定日期的間隔天數
import java.io.*;
class Date
{
 private int year;
 private int mouth;
 private int day;
 
 //構造方法
 public Date (int y,int m,int d)           
 {setDate(y,m,d);
 }
 //設置初始時間
 private void setDate (int y,int m,int d)         
 {year=y;
  mouth=m;
  day=d;
 }
 //加一天
 private void addDays()             
 {int i;
  day++;
  switch(mouth)
  {case 1:
   case 3:
   case 5:
   case 7:
   case 8:
   case 10:
   case 12:
        if(day>31)
         {day=1;
          mouth++;
          if(mouth==13)
            {mouth=1;
             year++;
            }
         }
         break;
   case 2:i=judgeYear(year);
          if(i==1)
           {if(day>29)
              {day=1;mouth++;}
           }
          else
           {if(day>28)
              {day=1;mouth++;}
           }
          break;
   case 4:
   case 6:
   case 9:
   case 11:if(day>30)
            {day=1;mouth++;}
  }
 }
 
 //減一天
 private void subDays()               
 {int i;
  day--;
  switch(mouth)
  {
   case 5:
   case 7:
   case 10:
   case 12:if(day==0)
            {day=30;
             mouth--;
             }
           break;
   case 3:
          if(day==0)
           {i=judgeYear(year);
            if(i==1)
              {day=29;mouth--;}
            else
              {day=28;mouth--;}
           }
          break;
   case 1:
   case 2:
   case 4:
   case 6:
   case 8:
   case 9:
   case 11:if(day==0)
            {day=31;
             mouth--;
             if(mouth==0)
              {mouth=12;year--;}
            }
  }
 }
 //判斷是不是潤年
 private int judgeYear(int year)     
 {int i;
  if(year%4==0) 
    i=1;
  else
    i=0;
  if((year%100==0)&&(year%400!=0))
    i=0;
  return i;
 }
 //計算當前日期與指定的某日的間隔天數
 //設置公元1年1月1日為基準點
 private int countDays(int y,int m,int d)
 {int i,n=0,k=0;
  //計算當前日期到基準點的間隔天數n
  for(i=1;i<year;i++)
  {if(judgeYear(i)==1)
     n=n+366;
   else
     n=n+365;
  }
  for(i=1;i<mouth;i++)
   {switch(i)
     {case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:n=n+31;break;
      case 2:if(judgeYear(year)==1)
               n=n+29;
             else
               n=n+28;
             break;
      case 4:
      case 6:
      case 9:
      case 11:n=n+30;break;
     }
   }
  n=n+day;
  
  //計算目標日期到基準點的間隔天數k
  for(i=1;i<y;i++)
  {if(judgeYear(i)==1)
     k=k+366;
   else
     k=k+365;
  }
  for(i=1;i<m;i++)
   {switch(i)
     {case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:k=k+31;break;
      case 2:if(judgeYear(y)==1)
               k=k+29;
             else
               k=k+28;
             break;
      case 4:
      case 6:
      case 9:
      case 11:k=k+30;break;
     }
   }
  k=k+d;
  //返回倆日期的間隔天數
 return (Math.abs(n-k));
 }
  //主方法
 public static void main (String[] args)throws IOException    
 {BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); 
  int y,m,d,days,j,n=0,k,p;
  String year,mouth,day,i;
  //創建新對象date
  Date date=new Date(0,0,0); 
  do{
  p=0;
  System.out.println("\n請設置當前日期");
  System.out.print(" 年份：");
  year=br.readLine();
  y=Integer.parseInt(year);
  
  System.out.print(" 月份: ");
  mouth=br.readLine();
  m=Integer.parseInt(mouth);
  
  System.out.print(" 日份: ");
  day=br.readLine();
  d=Integer.parseInt(day);
  
             
  switch(m)
   {case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12:if(d>31||d<1)
              {System.out.println("日期設置錯誤，請重新設置");p=1;}
            break;
            
    case 4:
    case 6:
    case 9:
    case 11:if(d>30||d<1)
              {System.out.println("日期設置錯誤，請重新設置");p=1;}
            break;
    case 2:k=date.judgeYear(y);
          if(k==1)
           {if(d>29||d<1)
              {System.out.println("日期設置錯誤，請重新設置");p=1;}
           }
          else
           {if(d>28||d<1)
              {System.out.println("日期設置錯誤，請重新設置");p=1;}
           }
          break;
    default:System.out.println("日期設置錯誤，請重新設置");
            p=1;
   }
  }while(p==1);
          
  date.setDate(y,m,d);
  System.out.println("當前日期："+date.year+"年"+date.mouth+"月"+date.day+"日");
              
  do{           
  System.out.println("\n功能菜單：");
  System.out.println(" 1.向前數日");
  System.out.println(" 2.向后數日");
  System.out.println(" 3.重新設置當前日期");
  System.out.println(" 4.計算當前日期與某天的間隔天數");
  System.out.println(" 5.退出");
  System.out.print("請輸入你的選擇：");
  
  i=br.readLine();
  n=Integer.parseInt(i); 
  switch(n)
  {case 1:System.out.println("\n當前日期："+date.year+"年"+date.mouth+"月"+date.day+"日");
          System.out.print("向前天數：");
          String D=br.readLine();
          days=Integer.parseInt(D);
          for(j=1;j<=days;j++ )
            date.addDays();
          System.out.println("目標日期："+date.year+"年"+date.mouth+"月"+date.day+"日");
          break;
          
   case 2:System.out.println("\n當前日期："+date.year+"年"+date.mouth+"月"+date.day+"日");
          System.out.print("向后天數：");
          String H=br.readLine();
          days=Integer.parseInt(H);
          for(j=1;j<=days;j++ )
             date.subDays();
          System.out.println("目標日期："+date.year+"年"+date.mouth+"月"+date.day+"日");
          break;
          
   case 3:System.out.println("\n請設置當前日期");
          System.out.print(" 年份：");
          year=br.readLine();
          y=Integer.parseInt(year);
  
          System.out.print(" 月份: ");
          mouth=br.readLine();
          m=Integer.parseInt(mouth);
  
          System.out.print(" 日份: ");
          day=br.readLine();
          d=Integer.parseInt(day); 
          
          date.setDate(y,m,d); 
          System.out.println("當前日期："+date.year+"年"+date.mouth+"月"+date.day+"日"); 
          break; 
          
   case 4:
          System.out.println("\n設置目標日期："); 
          System.out.print(" 年份：");
          year=br.readLine();
          y=Integer.parseInt(year);
  
          System.out.print(" 月份: ");
          mouth=br.readLine();
          m=Integer.parseInt(mouth);
  
          System.out.print(" 日份: ");
          day=br.readLine();
          d=Integer.parseInt(day); 
          
          System.out.println("\n當前日期："+date.year+"年"+date.mouth+"月"+date.day+"日"); 
          System.out.println("目標日期："+y+"年"+m+"月"+d+"日"); 
          System.out.println("間隔天數："+date.countDays(y,m,d));
               
  }
 }while(n!=5);
 }
}