【2019.07.03】java 编写一个程序，显示给定年月的日历

迈不过友情╰ 2021-12-14 20:37 261阅读 0赞

# 方法抽象、逐步求精 #

将方法的使用和她的实现分离  
自顶向下设计  
自底向上实现

package com.ybs.practice;
    
    import java.util.Scanner;
    
    /** * @Description 类描述：输入年份和月份，然后显示该月的整个日历 * @ClassName 类名称： * @author yb.w * @version 创建时间：2019年7月3日 下午4:42:01 */
    public class PrintCalendar { 
    	public static void main(String[] args) { 
    		@SuppressWarnings("resource")
    		Scanner input = new Scanner(System.in);
    		System.out.println("Enter full year (e.g., 2012): ");
    		int year = input.nextInt();
    		
    		System.out.println("Enter month as a number between 1 and 12: ");
    		int month = input.nextInt();
    		
    		printMonth(year, month);
    		
    	}
    
    	private static void printMonth(int year, int month) { 
    		printMonthTitle(year, month);
    		printMonthBody(year, month);
    	}
    	
    	private 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");
    	}
    	
    	private 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();
    		 }
    	}
    	
    	private static String getMonthName(int month) { 
    		String monthName = "";
    		switch (month) { 
    		case 1: monthName = "January"; break;
    		case 2: monthName = "Febrary"; 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 = "Auguest"; break;
    		case 9: monthName = "September"; break;
    		case 10: monthName = "October"; break;
    		case 11: monthName = "Nobermber"; break;
    		case 12: monthName = "December"; 
    		}
    		return monthName;
    	}
    	
    	private static int getStartDay(int year, int month) { 
    		// 获取月初第一日是星期几
    		final int START_DAY_FOR_1_1800 = 3;
    		int totalNumberOfDays = getTotalNumberOfDays(year, month);
    		
    		return (totalNumberOfDays + START_DAY_FOR_1_1800) % 7;
    	}
    	
    	private static int getTotalNumberOfDays(int year, int month) { 
    		// 1800年起到当前月第一日的总天数
    		int total = 0;
    		for (int i = 1800; i < year; i++) 
    			if (isLeapYear(year))
    				total += 366;
    			else
    				total += 365;
    		
    		// Add days form jan to the month prior to the calendar month
    		for (int i = 1; i < month; i++)
    			total += getNumberOfDaysInMonth(year, i);
    		
    		return total;
    	}
    	
    	private static int getNumberOfDaysInMonth(int year, int month) { 
    		// 获取这个月共多少天
    		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; // If month is incorrect
    	}
    	
    	private static boolean isLeapYear(int year) { 
    		return year % 400 == 0 || (year % 4 == 0 && year % 100 != 0); 
    	}
    }