java - return the day of the week based on the input date

/************************************************************   
Copyright (C), 1988-1999, Huawei Tech. Co., Ltd.   
FileName: main.cpp
  
Author: Light  
Version :   1.0       
Date:   2018/4/17
Description: Enter the date, return the day of the week // Module description         
Version: only for software testing, complete job // version info 
  
Function List: // Main functions and their functions     
1.
 History: 
  // history modification record 
      
	<author>  <time>   <version >   <desc>       
    Light 18/4/17 1.0 Build function

***********************************************************/

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String year = null;//year
		String month = null;//month
		String day = null;//Day
		
		//Enter the year, month and day
		@SuppressWarnings("resource")
		Scanner scanner1 = new Scanner(System.in);
		@SuppressWarnings("resource")
		Scanner scanner2 = new Scanner(System.in);
		@SuppressWarnings("resource")
		Scanner scanner3 = new Scanner(System.in);
		System.out.println("Please enter the year: ");
		year=scanner1.next();
		System.out.println("Please enter the month: ");
		month=scanner2.next();
		System.out.println("Please enter the date: ");
		day=scanner3.next();
		
		//Check if input is responsive
		System.out.println( "The input time is: " + year + "year" + month + "month" + day + "day");
		
		//Check if the input is a number or empty
		if(!isNumber(year) || !isNumber(month) || !isNumber(day) )
		{
			System.out.println("It is detected that your input is invalid, please enter a number!");
		}
		else
		{
			int year_rual=Integer.parseInt(year);
			int month_rual=Integer.parseInt(month);
			int day_rual=Integer.parseInt(day);
			
			//Check if the entered date is valid
			if (judge(year_rual,month_rual,day_rual))
			{
			　　String weekday=weekByDate(year_rual,month_rual,day_rual);
			　　System.out.println( year + " 年" + month + " 月" + day + " 日是  " + weekday);
			}
			else
			{
			　　System.out.println("It is detected that your input is invalid, please enter a valid date!");
			}
			
		}
	}
	
	/**
	 * Determine whether the entered year, month, and day are numbers or empty
	 * @param number //input content
	 * @return boolean//The return value is true to meet the rules, the return value of false does not meet the rules
	 */
	public static boolean isNumber(String number)
	{
		if (number == null || "".equals(number.trim()))
		{
			return false;
		}
		Pattern pattern = Pattern.compile("[0-9]*");
		
		Matcher isNum = pattern.matcher (number.trim ());
		
		if (isNum.matches())
		{
			return true;			
		}
		else
		{
			return false;
		}
	}
	
	
	/**
	 * Determine whether the entered year, month, and date conform to the rules
	 * @param year //year
	 * @param month // month
	 * @param day //day
	 * @return boolean//The return value is true to meet the rules, the return value of false does not meet the rules
	 */
	public static boolean judge (int year,int month,int day)
	{
	　//When the input number is less than zero, return false
	　　if (year <= 0)
	　　{                      
            　　　return false;  
      　　　}  
        　　if (month <= 0 || month > 12)
　　　　　　{   
          　　　　return false;  
        　　}  
          if (day<=0 || day > 31){  
              
                return false;  
          }  
        //The year is divisible by 4 and not divisible by 100, or if it is divisible by 400, it is a leap year  
        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))
        {  
            if (month == 2)
            {   
            	//February in leap year   
                if (day > 29)
                {  
                    return false;  
                }  
            }  
        }else{
        	// February is not a leap year   
            if (month == 2)
            {  
                if (day > 28)
                {  
                    return false;  
                }  
            }  
        }  
        //1, 3, 5, 7, 8, 10, and December are 31 days   
        int[] m1 = {1,3,5,7,8,10,12};
        
        for (int i = 0; i < m1.length; i++){  
            if (month == m1[i])
            {  
                if (day>31)
                {  
                     return false;  
                }  
            }  
        }  
        //4,6,9,12 months are 30 days   
        int[] m2 = {4,6,9,11};
        
        for (int j = 0; j < m2.length; j++)
        {  
            if (month == m2[j])
            {  
                if (day > 30)
                {  
                     return false;  
                }  
            }  
        }  
		
		return true;
	}
	
	
	/**
	 * Return the day of the week according to the year, month and day
	 * @param year //year
	 * @param month //month
	 * @param day //day
	 * @return String //The return value directly returns the day of the week
	 */
	public static String weekByDate (int year,int month,int day)
	{
	String str="";
        SimpleDateFormat fmt = new SimpleDateFormat("dd MM yyyy");
        
        Date d = null;
	try {
		d = fmt.parse(day+" "+month+" "+year);
	} 
　　　　　catch (ParseException e) 
        {
	　　// TODO Auto-generated catch block
	　　e.printStackTrace ();
	}
        
        Calendar cal = Calendar.getInstance();
        
        cal.setTime(d);
        
        int weekDay = cal.get(Calendar.DAY_OF_WEEK);
        
        switch(weekDay) {
            case 1 : str="SUNDAY"; break;
            case 2 : str="MONDAY"; break;
            case 3 : str="TUESDAY"; break;
            case 4 : str="WEDNESDAY"; break;
            case 5 : str="THURSDAY"; break;
            case 6 : str="FRIDAY"; break;
            case 7 : str="SATURDAY"; break;
            default: break;
        }
		
		return str;
	}

}