java achieve a simple calendar

 

package com.zx.text1;

import java.util.Scanner; // get input window function

import java.util.Calendar;

import java.util.Date; // get the time and date function

java.util.GregorianCalendar import;

import  java.text.*;

public class demo3 {

       public static void main (String[] args) throws ParseException{

             

             int maxDay = 0;

             int firstDay = 0;

             int currentDay = 0;

             

             System.out.println ( "Please enter a date in the format: 2019-01-01");

             Scanner sc = new Scanner(System.in);

             // Get the time format keyboard input

             String str = sc.nextLine();

             

             DateFormat format = new SimpleDateFormat("yyyy-MM-dd");

             Date date = format.parse(str);

             // convert string specified date format

             Calendar calendar = new GregorianCalendar();

             // will be converted to a calendar date

             calendar.setTime(date);

             maxDay = calendar.getActualMaximum (Calendar.DATE); // get the maximum number of

             currentDay = calendar.get(Calendar.DATE);

             // current date in the day before yesterday

             calendar.set(Calendar.DATE,1);

             // set the first day of the current page

             firstDay = calendar.get(Calendar.DAY_OF_WEEK);

             // current date in a few weeks the first day of the month corresponding

             System.out.println("--------------------------------------------------");

             System.out.println ( "Sunday \ t Monday \ t Tuesday \ t Wednesday \ t Thursday \ t Friday \ t Saturday");

             System.out.println("---------------------------------------------------");

             

             for(int j = 1;j < firstDay;j++) {

                    // output spaces before the current month

 

                    System.out.print("\t");

             }

             

             Number of Number // output each day of the month

             for(int i = 1;i <= maxDay;i++) {

                    // represents today's date

                    if(i == currentDay) {

                           System.out.print("");

                    }

                    System.out.print(i+"\t");

                    if ((i- (8-firstDay))% 7 == 0) {// 7 day cycle of the output of all the number of

                           System.out.println("\n");

                           

                    }

             }

             

             

       }

}