Algorithm Implementation/Date and time/Conversion of a Gregorian date to an International Fixed Calendar date

This Source code converts a Gregorian Calendar date into a International Fixed Calendar date. The Gregorian date can be abbreviated, or

nothing entered for today's date. The program is in 2 classes: IFCConverter and TestIFCConverter.

Java

public class IFCConverter {
    private String gregDate;//a gregorian date
    private String IFCdate;//an International fixed calendar date
    private static final String[] MONTHS = {"January", "February", "March", "April", "May", "June", "Midi", "July", "August", "September", "October", "November", "December"};//creates an constant array of months
    
    //sets gregDate
    public void setGregDate(String gD) {
        if (gD.contains("  ") && !gD.startsWith(" ")) { //if the spaces won't //drive later code wacko
            gregDate = gD;
        }
    }
    
    //gets IFCdate
    public String getIFCdate() {
        return IFCdate;
    }

    public void GregIFC() {
        String month = gregDate.substring(0, gregDate.indexOf(' '));//separates the Month part of the date
        int monthNum = monthNum(month);//sets a month # equal to the Number of the //month (0 fo Jan., 1 for Feb., etc.)
        int[] cfs = {0, 3, 3, 6, 8, 11, 13, 0, -12, -9, -7, -4, -2};//sets the conversion factors
        String dayStr = gregDate.substring(gregDate.indexOf(' ') + 1);//separates the day of the month
        int day = Integer.parseInt(dayStr);//parses the day string into a number
        day += cfs[monthNum];//sets IFC day of month
        if (day > 28 && monthNum != 12) {//if IFC date is greater than 28 and it //isn't the 29 day month
            day -= 28;
            month = MONTHS[monthNum + 1];//subtract 28 and go to the next month
        }
        if (day < 1) {//if IFC date is less than 1
            day += 28;
            month = MONTHS[monthNum - 1];//add 28 and go to previous month
        }
        IFCdate = month + " " + day;//sets IFCdate equal to final month and day
        if (gregDate.equals("December 31")) {//because in the International Fixed Calendar, there's no Dec. //29
            IFCdate = "Extra day";
        }
    }

    public int monthNum(String month) {
        String subMonth = month.substring(0, 3);//so abbreviations will work
        for (int monthN = 0; monthN < MONTHS.length; monthN++) {//don't want to have the index be out of bounds
            if (subMonth.equals(MONTHS[monthN].substring(0, 3))) {//if month equals current month
                break;//leave monthN where it is
            }
        }
        return monthN;
    }
}

Test code

import java.util.*;
import java.text.*;
import java.io.*;

public class TestIFCConverter {
    public static void main(String[] args) {
        String input = TestIFCConverter.javaInput("enter a date:");//prompts the user to enter a date
        IFCConverter ifcc = new IFCConverter();//makes a reference to IFCConverter
        ifcc.setGregDate(input);//sets the Greg. date to the date string earlier made
        if (input.equals("")) {
            Date today = new Date();//Sets a variable equal to the current date
            String date = DateFormat.getDateInstance(DateFormat.LONG).format(today);//formats today to MONTH Date, YEAR
            ifcc.setGregDate(date.substring(0, date.length() - 6));//separates the year
        }
        ifcc.GregIFC();//converts the Greg. date to IFC
        System.out.println(ifcc.getIFCdate());//prints the IFC Date
    }

    public static String javaInput(String prompt) {
        String inputLine = null;
        System.out.print(prompt + " ");
        try {
            BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
            inputLine = is.readLine();
        } catch (IOException e) {
            System.err.println("IOException: " + e);
        }
        return inputLine;
    }
}