Java编写日历表的3种方式

 //指定的日历年份
    public static int year;
    //指定的日历月份
    public static int month;
​
    //获得总天数
    public static int getDaysFrom1900() {
        int days = 0;
        //统计从1900年到指定日历年份的前一年的天数
        for (int i = 1900; i < year; i++) {
            days += isLeapYear(i) ? 366 : 365;
        }
        //统计从一月到指定日历月份的前一个月的天数
        for (int i = 1; i < month; i++) {
            days += getDaysFromMonth(i);
        }
        return days;
    }
 //获取指定月份的天数
    private static int getDaysFromMonth(int month) {
        switch (month) {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                return 31;
            case 2:
                return isLeapYear(year) ? 29 : 28;
            default:
                return 30;
        }
    }
​
    //判断指定年份是平年还是闰年
    private static boolean isLeapYear(int year) {
        return (year % 4 == 0 && year % 100 != 0 || year % 400 == 0);
    }

 //显示日历
    public static void show() {
        //获取从1900年到指定月份前一个月的总天数
        int totalDays = getDaysFrom1900();
        //获取指定月份的天数
        int daysOfMonth = getDaysFromMonth(month);
        //获取指定月份第一天前面的空格数
        int space = totalDays % 7;
        //计数器
        int count = 0;
        //显示
        System.out.println("一\t二\t三\t四\t五\t六\t日");
        System.out.println("==========================");
        for (int i = 0; i < space; i++) {
            count++;
            System.out.print("\t");
        }
        for (int i = 1; i <= daysOfMonth; i++) {
            count++;
            System.out.print(i + "\t");
            if (count % 7 == 0) {
                count = 0;
                //换行
                System.out.println();
            }
        }
}

public static void show(int y, int m) {
        //获取当前系统时间
        Calendar c = Calendar.getInstance();
        //获取当前的日期
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH) + 1;
        int day = c.get(Calendar.DAY_OF_MONTH);
        //设置指定的日期
        c.set(Calendar.YEAR,y);
        c.set(Calendar.MONTH,m-1);
        c.set(Calendar.DAY_OF_MONTH, 1);
        //获取指定月份的总天数
        int dayOfMonth = c.getActualMaximum(Calendar.DAY_OF_MONTH);
        //获取指定月份第一天的星期
        int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - 1;
        //显示
        System.out.println("一\t二\t三\t四\t五\t六\t日");
        System.out.println("==========================");
        dayOfWeek = dayOfWeek == 0 ? 7 : dayOfWeek;
        //获取指定月份前面的空格数
        int space = dayOfWeek - 1;
        int count = 0;
        for (int i = 0; i < space; i++) {
            count++;
            System.out.print("\t");
        }
        for (int i = 1; i <= dayOfMonth; i++) {
            count++;
            //判断是不是当前系统的日期时间
            String date = (y == year && m == month && i == day) ?
            "*" + i + "\t" : i + "\t";
            System.out.print(date);
            if (count % 7 == 0) {
                count = 0;
                System.out.println();
            }
        }
​
    }

public static void show(int y, int m) {
        //获取当前系统时间
        LocalDate date = LocalDate.now();
        //获取当前的日期
        int year = date.getYear();
        int month = date.getMonth().getValue();
        int day = date.getDayOfMonth();
        //设置指定的日期
        LocalDate date1 = LocalDate.of(y,m,1);
        //获取指定月份的总天数
        int daysOfMonth = date1.getMonth()
        .length(y % 4 == 0 && y % 100 != 0 || y % 400 == 0);
        //获取指定月份前面的空格数
        int space= date1.getDayOfWeek().getValue()-1;
        System.out.println("一\t二\t三\t四\t五\t六\t日");
        System.out.println("==========================");
        int count = 0;
        for (int i = 0; i < space; i++) {
            count++;
            System.out.print("\t");
        }
        for (int i = 1; i <= daysOfMonth; i++) {
            count++;
            //判断是不是当前系统的日期时间
            String src = (y == year && m == month && i == day) ?
            "*" + i + "\t" : i + "\t";
            System.out.print(src);
            if (count % 7 == 0) {
                count = 0;
                System.out.println();
            }
        }
    }

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入年份:");
        int year = sc.nextInt();
        System.out.println("请输入月份:");
        int month = sc.nextInt();
        show(year, month);
    }