java日历程序

以下是一个简单的Java日历程序，它可以根据用户输入的年份和月份计算并显示一个月的日历：

import java.util.*;

public class CalendarProgram {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter year (e.g. 2022): ");
        int year = input.nextInt();
        System.out.print("Enter month (1-12): ");
        int month = input.nextInt();
        
        // Create a Calendar object and set the year and month
        Calendar cal = Calendar.getInstance();
        cal.set(year, month-1, 1); // Note: months are 0-based in Calendar
        
        // Get the number of days in the given month
        int numDays = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
        
        // Print the header for the calendar
        System.out.println(" Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        
        // Print the calendar
        int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
        for (int i = 1; i < dayOfWeek; i++) {
            System.out.print("     ");
        }
        for (int day = 1; day <= numDays; day++) {
            System.out.printf("%4d", day);
            if (dayOfWeek == 7) {
                System.out.println();
                dayOfWeek = 1;
            } else {
                dayOfWeek++;
            }
        }
        System.out.println();
    }
}

该程序首先要求用户输入一个年份和一个月份，然后使用Calendar类来计算该月的日历。程序首先获取该月的天数，然后打印日历的表头，并使用for循环打印日历中的每一天。程序在打印每一天之前会计算出该天是星期几，并根据需要插入一些空格来使日历排版正确。