控制檯日曆打印-Java小程序

package com.demo.yongjian;

import java.util.Scanner;

public class PrintCalendar {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		System.out.println("Enter full year (e.g.,2001): ");
		int year = input.nextInt();

		System.out.println("Enter month in month between 1 and 12:");
		int month = input.nextInt();

		printMonth(year, month);
	}

	public static void printMonth(int year, int month) {
		printMonthTitle(year, month);
		printMonthBody(year, month);
	}

	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");
	}

	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 = "August";
			break;
		case 9:
			monthName = "September";
			break;
		case 10:
			monthName = "October";
			break;
		case 11:
			monthName = "November";
			break;
		case 12:
			monthName = "December";
		}
		return monthName;
	}
	
	public static void printMonthBody(int year, int month){
		int startDay = getStartDay(year, month);
		int numberOfDaysInMonth = getNumberOfDaysInMonth(year, 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();
	}
	
	public static int getStartDay(int year, int month){
		final int START_DAY_FOR_JAN_1_1800 = 3;//初始化爲3
		int totalNumberOfDays = getTotalNumberOfDays(year, month);
		return (totalNumberOfDays + START_DAY_FOR_JAN_1_1800) % 7;
		
	}
	
	public static int getTotalNumberOfDays(int year, int month){
		int total = 0;
		for(int i = 1800; i < year; i++)
			if(isLeapYear(i))
				total = total + 336;
			else
				total = total + 365;
		for(int i = 1; i < month; i++)
			total = total + getNumberOfDaysInMonth(year, i);
		return total;
	}
	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;
		if( month == 4 || month == 6 || month == 9 || month == 11)
			return 30;
		if(month == 2)
			return isLeapYear(year) ? 29 : 28;
		return 0;
	}
	
	public static boolean isLeapYear(int year){
		return year % 400 == 0 || (year % 4 == 0 && year % 100 != 0);
	}
}