效果

输入年份、月份，输出日历。

代码

    package com.software.oop;

    import java.util.Calendar;
    import java.util.Scanner;

    public final class MyCalendar {

        private Calendar calendar;
        //field：域  对应  字段（属性）
        public MyCalendar(){
            //对象实例化，抽象类不能用new调用，只能调用抽象类的子类或者查找参考文档中能调用的。
            calendar = Calendar.getInstance();
        }

        /*
         *1.一个月的第一天是星期几
         *2.判断是否为闰年
         *3.求一个月的天数
         */
        //判断是否为闰年
        public boolean isLeapYear(int year){
            if (year % 400 == 0||(year % 4 == 0 && year %100 != 0))
                return true;
            else 
                return false;
        }
        //判断月份天数
        public int getDays(int year,int month) {
            if(month == 1||month == 3 || month == 5 ||month == 7 || month == 8 ||month == 10 || month == 12)
                return 31;
            if(isLeapYear(year) && month ==2)
                return 29;
            if(!isLeapYear(year) && month == 2)
                return 28;
            if(month == 4||month == 6||month == 9||month == 11)
                return 30;
            return 0;
        }

        public void display() {
            int firstDay;//定义临时变量
            int flag = 0;//控制换行
            //输入
            int year,month;
            Scanner scanner = new Scanner(System.in);
            System.out.println("请输入年份：");
            year = scanner.nextInt();
            System.out.println("请输入月份(1-12)：");
            month = scanner.nextInt();
            //定位到输入的年月份
            calendar.set(Calendar.YEAR, year);
            calendar.set(Calendar.MONTH, month-1);

            System.out.print("\t------------");
            System.out.println(calendar.get(Calendar.YEAR)+"年"+(calendar.get(Calendar.MONTH)+1)+"月-------------");
            System.out.println("\n日\t一\t二\t三\t四\t五\t六");
            //定位到本月1日
            calendar.set(Calendar.DATE, 1);
            //获取到本月1日是周几
            firstDay = calendar.get(Calendar.DAY_OF_WEEK);
            //System.out.println(firstDay);
            //输出本月1日前的空白
            for (int i = 1; i < firstDay; i++) {
                System.out.print("\t");
                flag++;
            }
            //输出日与日之间的空格
            for (int i = 1; i <= getDays(year, month); i++) {
                System.out.print(i);
                System.out.print("\t");
                flag++;
                //输出换行
                if (flag % 7 == 0) {
                    System.out.println("\n");
                }
            }
            /*calendar.set(Calendar.YEAR, 1995);//set修改
            System.out.print("现在是"+calendar.get(Calendar.YEAR)+"年");
            System.out.print(calendar.get(Calendar.MONTH)+1+"月");//月份从0开始，所以加1
            System.out.print(calendar.get(Calendar.DATE)+"日");
            System.out.print(calendar.get(Calendar.HOUR_OF_DAY)+"时");
            System.out.print(calendar.get(Calendar.MINUTE)+"分");
            System.out.print(calendar.get(Calendar.SECOND)+"秒");*/
        }

        public static void main(String[] args) {
            MyCalendar myCalendar = new MyCalendar();
            myCalendar.display();
        }

    }