Java实现万年历

左手的ㄟ右手 2024-03-26 21:14 71阅读 0赞

### 1. 不借助任何时间API实现 ###

*  先求出每月的第一天是星期几，再求出每个月一共有多少天，而且也要判断年份是否是闰年。
 *  根据每月的第一天是星期几得出前面要打印多少空格。
 *  每打印七天就换一次行。

boolean isLeap(int year){
        
            return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
        }
        int getDaysOfMonth(int year, int month){
        
            switch (month){
        
                case 4:
                case 6:
                case 9:
                case 11:
                    return 30;
                case 2:
                    if (isLeap(year))
                        return 29;
                    else
                        return 28;
                default:
                    return 31;
            }
        }

Scanner scanner = new Scanner(System.in);
            System.out.println("请输入年份：");
            int year = scanner.nextInt();
            System.out.println("请输入月份：");
            int month = scanner.nextInt();
            int days=0;
            for (int i = 1900; i < year; i++){
        
                if (isLeap(i)){
        
                    days += 366;
                }else {
        
                    days += 365;
                }
            }
            for (int i = 1; i < month; i++) {
        
                days+=getDaysOfMonth(year, i);
            }
            int dayOfWeek = (days+1)%7;
            System.out.println("一\t二\t三\t四\t五\t六\t日");
            for (int i = 0; i < dayOfWeek - 1; i++) {
        
                System.out.print("\t");
            }
            int daysOfMonth = getDaysOfMonth(year, month);
            for (int i = 1; i <= daysOfMonth; i++) {
        
                System.out.print(i+"\t");
                if ((dayOfWeek-1+i)%7==0)
                    System.out.println();
            }
            scanner.close();

![在这里插入图片描述][5af01e3f23814a69839a6b800aa25f18.png]

### 2. Calendar类 ###

先切换到对应的年月日，再利用getActualMaximum(Calendar.DAY\_OF\_MONTH)获取当月一共有多少天，Calendar.DAY\_OF\_WEEK获取当天是星期几。

Scanner scanner = new Scanner(System.in);
            System.out.println("请输入年份：");
            int year = scanner.nextInt();
            System.out.println("请输入月份：");
            int month = scanner.nextInt();
            Calendar calendar = Calendar.getInstance();
            calendar.set(Calendar.YEAR,year);
            calendar.set(Calendar.MONTH,month - 1);
            calendar.set(Calendar.DAY_OF_MONTH,1);
            int maxDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
            System.out.println("一\t二\t三\t四\t五\t六\t日");
            int week = calendar.get(Calendar.DAY_OF_WEEK) - 1;
            if (week == 0)
                week = 7;
            for (int i = 0; i < week - 1; i++) {
        
                System.out.print("\t");
            }
            for (int i = 1; i <= maxDay; i++) {
        
                System.out.print(i + "\t");
                if ((week+i-1) % 7 == 0)
                    System.out.println();
            }
            scanner.close();

### 3. JDK8的LocalDate ###

LocalDate.of()设置日期，localDate.getDayOfWeek()获取星期，localDate.lengthOfMonth()获取月份天数。

Scanner scanner = new Scanner(System.in);
            System.out.println("请输入年份：");
            int year = scanner.nextInt();
            System.out.println("请输入月份：");
            int month = scanner.nextInt();
            LocalDate localDate = LocalDate.of(year, month,1);
            DayOfWeek dayOfWeek = localDate.getDayOfWeek();
            System.out.println("一\t二\t三\t四\t五\t六\t日");
            for (int i = 0; i < dayOfWeek.getValue() - 1; i++) {
        
                System.out.print("\t");
            }
            for (int i = 1; i <= localDate.lengthOfMonth(); i++) {
        
                System.out.print(i + "\t");
                if ((dayOfWeek.getValue() + i - 1 )% 7 == 0)
                    System.out.println();
            }
            scanner.close();

### 2.测试： ###

![在这里插入图片描述][5c4d8b8d9eac481bb78015004b7f41f0.png]

[5af01e3f23814a69839a6b800aa25f18.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/25/7209d1a533c6452cbeccc560a75fc88e.png
[5c4d8b8d9eac481bb78015004b7f41f0.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/25/d9648293ce5940c9848333ceae6269ef.png