打印日历,已知1800.1.1是星期三(START_DAY_FOR_JAN-1_1800=3),打印某年某月的日历
package choice;
import java.util.Scanner;
public class Choose{
public static void main(String[] args){
Scanner input = new Scanner (System.in);
//prompt the user to enter year
System.out.print("Enter full year(e.g.,2012): ");
int year = input.nextInt();
//prompt the user to enter month
System.out.print("Enter moth as a number between 1 and 12: ");
int month = input.nextInt();
//print calendar for the month of the year
printMonth(year,month);
}
/**print the calendar for a month in a year**/
public static void printMonth (int year ,int month){
//print the headings of the calendar
printMonthTitle(year,month);
//print the body of the calendar
printMonthBody(year,month);
}
/**print the month title, e.g., March 2012*/
public static void printMonthTitle(int year,int month){
System.out.println(" "+getMonthName(month)+" "+year);
System.out.println("-----------------------------");
System.out.println("Sun Mon Tue Wed Thu Fri Sat");
}
/**get the English name for the month*/
public static String getMonthName(int month){
String monthName="";
switch (month){
case 1: monthName = "January"; break;
case 2: monthName = "February"; break;
case 3: monthName = "March"; break;
case 4: monthName = "April"; break;
case 5: monthName = "May"; break;
case 6: monthName = "June"; break;
case 7: monthName = "July"; break;
case 8: monthName = "Augeust"; break;
case 9: monthName = "September"; break;
case 10: monthName = "October"; break;
case 11: monthName = "November"; break;
case 12: monthName = "December";
}
return monthName;
}
/**print month body*/
public static void printMonthBody(int year,int month){
//get start day of the week for the first data in the month
int startDay = getStartDay(year,month);
//Get number of days in the month
int numberOfDaysInMonth = getNumberOfDaysInMonth(year,month);
//pad space before the first day of the month
int i =0 ;
for( i=0 ;i<= startDay; i++){
System.out.print(" ");
}
for(i = 1;i <=numberOfDaysInMonth;i++){
System.out.printf("%4d",i);
if((i + startDay) % 7 == 0)
System.out.println();
}
System.out.println();
}
/**get the start day of month/1/year*/
public static int getStartDay(int year ,int month){
final int START_DAY_FOR_JAN_1_1800 = 3;
//get total number of days from 1/1/1800 to month/1/year
int totalNumberOfDays = getTotalNamerOfDays(year ,month);
//return the start day for month/1/year
return (totalNumberOfDays + START_DAY_FOR_JAN_1_1800 % 7);
}
/**get the total number of days since January 1,1800*/
public static int getTotalNamerOfDays(int year, int month){
int total = 0;
//get the total days from 1800 to 1/1 year
for(int i = 1800;i<year;i++)
if(isLeapYear(i))
total +=366;
else
total += 365;
//add days from Jan to the month prior to thar=e calender month
for(int i=1 ;i< month;i++)
total = total +getNumberOfDaysInMonth(year,i);
return total;
}
/**get the number of days in month*/
public static int getNumberOfDaysInMonth(int year ,int month){
if(month == 1 || month == 3||month == 5|| month == 7|| month ==8||month == 10 || month== 12)
return 31;
else if(month == 4 || month == 6 || month == 9|| month == 11)
return 30;
else if( month == 2)
return isLeapYear(year) ? 29 : 28;
return 0;
}
/**determine if it is a leap year*/
public static boolean isLeapYear(int year){
return year % 400 == 0 ||(year %4 == 0 && year %100 != 0);
}
}