Assignment #96 and Month Offset

Code

///John Mulligan
///period 5
///Program Name: Weekday Calculator
///File Name: WeekdayCalculator.java


      import java.util.Scanner;
    
    public class WeekdayCalculator
    {
    	public static void main( String[] args )
    	{
    		Scanner keyboard = new Scanner(System.in);
    
    		System.out.println("Welcome to Mr. Davis's fantastic birth-o-meter!");
    		System.out.println();
    		System.out.println("All you have to do is enter your birth date, and it will");
    		System.out.println("tell you the day of the week on which you were born.");
    		System.out.println();
    		System.out.println("Some automatic tests....");
    		System.out.println("12 10 2003 => " + weekday(12,10,2003));
    		System.out.println(" 2 13 1976 => " + weekday(2,13,1976));
    		System.out.println(" 2 13 1977 => " + weekday(2,13,1977));
    		System.out.println(" 7  2 1974 => " + weekday(7,2,1974));
    		System.out.println(" 1 15 2003 => " + weekday(1,15,2003));
    		System.out.println("10 13 2000 => " + weekday(10,13,2000));
    		System.out.println();
    
    		System.out.println("Now it's your turn!  What's your birthday?");
    		System.out.print("Birth date (mm dd yyyy): ");
    		int mm = keyboard.nextInt();
    		int dd = keyboard.nextInt();
    		int yyyy = keyboard.nextInt();
            
    		System.out.println("You were born on " + weekday(mm, dd, yyyy));
    	}
    
    
    	public static String weekday( int mm, int dd, int yyyy )
    	{
    		int yy, total;
    		String date = "";
            
            yy = yyyy - 1900;
            total = yy / 4;
            total = total + yy;
            total = total + dd;
            total = total + monthOffset(mm);
            
            if (isLeap(yyyy) == true && mm == 1 || mm == 2)
            {
                total--;
            }
            
            int remain = total % 7;     
    
    		date = WeekdayName(remain) + ", " + month_name(mm) + ", " + dd + ", " + yyyy;
    
    		return date;
    	}
    
        public static int monthOffset( int mm )
        	{
        		int result;
        		
                if (mm == 1)
                    result = 1;
                else if (mm == 2)
                    result = 4;
                else if (mm == 3)
                    result = 4;
                else if (mm == 4)
                    result = 0;
                else if (mm == 5)
                    result = 2;
                else if (mm == 6)
                    result = 5;
                else if (mm == 7)
                    result = 0;
                else if (mm == 8)
                    result = 3;
                else if (mm == 9)
                    result = 6;
                else if (mm == 10)
                    result = 1;
                else if (mm == 11)
                    result = 4;
                else if (mm == 12)
                    result = 6;
                else 
                    result = -1;            
        		
        		return result;
        	}
        
            public static String month_name( int mm )
        	{
        		String result;
        		
              
                if (mm == 1)
                    result = "January";
                else if (mm == 2)
                    result = "February";
                else if (mm == 3)
                    result = "March";
                else if (mm == 4)
                    result = "April";
                else if (mm == 5)
                    result = "May";
                else if (mm == 6)
                    result = "June";
                else if (mm == 7)
                    result = "July";
                else if (mm == 8)
                    result = "August";
                else if (mm == 9)
                    result = "September";
                else if (mm == 10)
                    result = "October";
                else if (mm == 11)
                    result = "November";
                else if (mm == 12)
                    result = "December";
                else
                    result = "ERROR";
                    
        		return result;
        
        	}
    	
            public static String WeekdayName( int remain )
            {
                String result;
                
                if (remain == 0)
                    result = "Sunday";
                else if (remain == 1)
                    result = "Monday";
                else if (remain == 2)
                    result = "Tuesday";
                else if (remain == 3)
                    result = "Wednesday";
               
                else if (remain == 4)
                    result = "Thursday";
                
                else if (remain == 5)
                    result = "Friday";
               
                else if (remain == 6)
                    result = "Satruday";
               
                else
                    result = "ERROR";
                    
                return result;
            }
    		
    	public static boolean isLeap( int year )
    	{
    		// years which are evenly divisible by 4 are leap years,
    		// but years divisible by 100 are not leap years,
    		// though years divisible by 400 are leap years
    		boolean result;
    
    		if ( year%400 == 0 )
    			result = true;
    		else if ( year%100 == 0 )
    			result = false;
    		else if ( year%4 == 0 )
    			result = true;
    		else
    			result = false;
    		
    		return result;
    	}
    }