使用Java實現萬年曆。
程式碼如下：

package com.oraleoaec.test;
import java.util.Calendar;
import java.util.Scanner;
public class TestDate {
    private static int year; // 定義年份
    public static void main(String[] args) {
        int month; // 定義月份
        int dayNumber = 0;//該月的天數
        String[] days = new String[38
 
];//定義這個月的天數（陣列日曆）
        Scanner sc = new Scanner(System.in);
        System.out.print("請輸入年份：");
        year = sc.nextInt();
        while (year < 1) {
            System.out.print("你輸入的年份有誤，請重新輸入：");
            year = sc.nextInt();
        }
        System.out.print("請輸入月份：");
        month = sc.nextInt();
        while
 
 (month < 1 || month > 12) {
            System.out.print("你輸入的月份有誤，請重新輸入：");
            month = sc.nextInt();
        }
        dayNumber = dayNumber(month);
        if(isLeapYear(year)){
            System.out.println(year+"年為閏年，這個月有："+dayNumber+"天！");
        }else{
            System.out.println(year+"年為平年，這個月有："
 
+dayNumber+"天！");
        }
        // 輸出表頭
        System.out.println("---------------------" + year + "年" + month + "月" + "---------------------");
        System.out.println();
        System.out.println("日\t一\t二\t三\t四\t五\t六");
        //設定時間
        Calendar calendar = Calendar.getInstance();
        calendar.set(year, month-1,1);
        //初始化日曆陣列
        for(int i = 0; i < days.length; i++){
            days[i] = " ";
        }
        //賦值
        int j = 1;
        for(int i = calendar.get(Calendar.DAY_OF_WEEK)-1; i < days.length; i++,j++){
            if(j <= dayNumber){
                days[i] += j;
            }
        }
        //輸出日曆陣列，遇七換行
        for(int i = 0; i < days.length; i++){
            if(i%7==0){
                System.out.println();
            }
            System.out.print(days[i]+"\t");
        }
    }
    //計算天數
    public static int dayNumber(int month){
        int dayNumber = 0;
        switch(month){
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            dayNumber = 31;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            dayNumber = 30;
            break;
        case 2:
            if(isLeapYear(year)){
                dayNumber = 29;
            }else{
                dayNumber = 28;
            }
            break;
        default:
            System.out.println("你輸入的月份有誤！");
        }
        return dayNumber;
    }
    // 判斷閏年
    public static boolean isLeapYear(int year) {
        if (year % 100 == 0) {
            if (year % 400 == 0) {
                return true;
            }
        } else {
            if (year % 4 == 0) {
                return true;
            }
        }
        return false;
    }
}

執行結果如圖所示：