日历 练习

import java.util.*;

public class Calendar {
    int year = 0;
    int month = 0;
    int sum = 0;
    int weekday;
    int monthday = 0;

    public void check() {
        System.out.println("先输入年份:");
        Scanner sc = new Scanner(System.in);
        int year = sc.nextInt();
        if (year < 1990 || year > 2100) {
            System.out.println("输入非法");
            return;
        }
        System.out.println("在输入月份:");
        int month = sc.nextInt();
        if (month < 1 || month > 12) {
            System.out.println("输入非法");
            return;
        }
        for (int i = 1990; i < year; i++) {
            if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0) {
                sum += 366;
            } else {
                sum += 365;
            }
        }
        for (int i = 1; i < month; i++) {
            if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                if (i == 2) {
                    sum += 29;
                } else if (i == 4 || i == 6 || i == 9 || i == 11) {
                    sum += 30;
                } else {
                    sum += 31;
                }
            } else {
                if (i == 2) {
                    sum += 28;
                } else if (i == 4 || i == 6 || i == 9 || i == 11) {
                    sum += 30;
                } else {
                    sum += 31;
                }
            }

        }
        weekday = (sum += 1) % 7;
        // System.out.println(weekday);
        System.out.println("日	一	二	三	四	五	六");
        for (int i = 0; i <= weekday; i++) {
            if (i == weekday) {
                System.out.print("1	");
                if (sum % 7 == 6) { // 余数得6的为周六,换行
                    System.out.print("
");
                }
                sum += 1;
                break;
            }
            System.out.print("	");
        }
        if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {// 是否为闰年
            if (month == 2) {
                monthday = 29;
            }

            else if (month == 4 || month == 6 || month == 9 || month == 11) {

                monthday = 30;
            } else {
                monthday = 31;
            }
        } else {
            if (month == 2) {
                monthday = 28;
            } else if (month == 4 || month == 6 || month == 9 || month == 11) {

                monthday = 30;
            } else {
                monthday = 31;
            }

        }
        for (int i = 2; i <= monthday; i++) {
            if (sum % 7 == 6) { // 余数得6的为周六,换行
                System.out.print(i + "
");
                sum += 1;
            } else {
                System.out.print(i + "	");
                sum += 1;
            }
        }
    }
}

基础差这点东西搞好久

主要区分平年闰年,算1990至查询月份的1号共多少天    天数%7   模为1号的星期数,并且打印时周六(天数%7模为6的)换行