printcalendar.java

一个java写的日历程序

public class PrintCalendar 
{
	//Main method
	public static void main(String[] args)
	{
		//The user enters year and month
		System.out.print("Enter full year: ");
		int year = MyInput.readInt();
		System.out.print("Enter month in number 1 and 12: ");
		int month = MyInput.readInt();
		
		//Print calendar for the month of the year
		printMonth(year,month);
	}
	
	//Print calender for the month in a year
	static void printMonth(int year,int month)
	{
		//Get start day of the week for the first date in the month
		int startDay = getStartDay(year,month);
	
		//Get number of days in the month
		int  numOfDaysInMonth = getNumOfDaysInMonth(year,month);
			
		//Print headings
		printMonthTitle(year,month);
			
		//Print body 
		printMonthBody(startDay,numOfDaysInMonth);
	}
		
	//Get the start day of the first day in a month
	static int getStartDay(int year,int month)
	{
		//Get totalNumber of dys since 1/1/1900
		int startDay1900 = 1;
		long totalNumOfDays = getTotalNumOfDays(year,month);
			
		//Return the start day
		return (int)((totalNumOfDays + startDay1900)%7);
	}
		
	//Get the total number of days since Jan 1,1900
	static long getTotalNumOfDays(int year,int month)
	{
		long total = 0;
			
		//Get the total days from 1900 to year -1
		for(int i = 1900; i < year; i++)
			if (isLeapYear(i))
				total = total + 366;
			else
				total = total + 365;
			
		//Add days from Jan to the month prior to the dalender month
		for(int i = 1;i < month; i++)
			total = total + getNumOfDaysInMonth(year,i);
		
		return total;
	}
		
	//Get the number of days in a month
	static int getNumOfDaysInMonth(int year,int month)
	{
		if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
			return 31;
		
		if (month == 4 || month == 6 || month == 9 || month == 11)
			return 30;
		
		if (month == 2)
			if (isLeapYear(year))
				return 29;
			else 
				return 28;
		return 0;
	}
		
	//Determine if it is a leap year
	static boolean isLeapYear(int year)
	{
		if ((year%400 == 0) || ((year % 4 == 0) && (year % 100 != 0)))
			return true;
			
		return false;
	}
		
	//Ptint month body
	static void printMonthBody(int startDay, int numOfDaysInMonth)
	{
		//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 <= numOfDaysInMonth; i++)
		{
			if(i<10)
				System.out.print("   " + i);
			else
				System.out.print("  " + i);
			if ((i + startDay)%7 == 0)
				System.out.println();
		}
		System.out.println();
	}
		
	//Print the month tital
	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
	static String getMonthName(int month)
	{
		String monthName = null;
		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 = "August";break;
			case 9:monthName = "September";break;
			case 10:monthName = "Octber";break;
			case 11:monthName = "November";break;
			case 12:monthName = "December";
		}
			
		return monthName;
	}
}