DateConverter.java

import java.util.Scanner;

class MonthException extends Exception {
    public MonthException() {
        System.out.println("Error in month number.");
        System.out.println("Please re-enter date.");
        System.exit(0);
    }
}

class DayException extends Exception {
    public DayException() {
        System.out.println("Error in day number.");
        System.out.println("Please re-enter date.");
        System.exit(0);
    }
}

class YearException extends Exception {
    public YearException() {
        System.out.println("Error in year number.");
        System.out.println("Please re-enter date.");
        System.exit(0);
    }
}

public class DateConverter {

    /**
    *   Program:    DateConverter.java
    *   Purpose:    Yahoo! Answers
    *   Creator:    Chris Clarke
    *   Created:    12.11.2014
    */

    public static boolean isLeapYear(int year) {
         return (year%4 == 0 && (year%100 != 0 || year%400 == 0));
    } // isLeapYear()

    public static String getMonthName(int m) {
        switch (m) {
            case 1:     return "January";
            case 2:     return "February";
            case 3:     return "March";
            case 4:     return "April";
            case 5:     return "May";
            case 6:     return "June";
            case 7:     return "July";
            case 8:     return "August";
            case 9:     return "September";
            case 10:    return "October";
            case 11:    return "November";
            case 12:    return "December";
        } // switch
        return "Error in month name!";
    } // getMonthName()

    public static void main(String[] args) throws MonthException, DayException, YearException {
        Scanner in  = new Scanner(System.in);
        String date;
        String[] d;
        String monthName;
        int month, day, year;
        int daysInMonth;

        System.out.print("Enter date <mm/dd/yyyy> : ");
        date = in.nextLine();
        d = date.split("/");

        month = Integer.parseInt(d[0]);
        day = Integer.parseInt(d[1]);
        year = Integer.parseInt(d[2]);

        if (month<1 || month>12) {
            throw new MonthException();
        } // if

        if (month==2) {
            if (isLeapYear(year))
                daysInMonth = 29;
            else
                daysInMonth = 28;
        } else if (month==1 || month==3 || month==5 || month==7
         || month==8 || month==10 || month==12) {
            daysInMonth = 31;
        } else {
            daysInMonth = 30;
        } // if

        if (day<1 || day>daysInMonth) {
            throw new DayException();
        } // if

        if (year<1000 || year>3000) {
            throw new YearException();
        } // if

        monthName = getMonthName(month);
        System.out.println(monthName+" "+day+", "+year);
    } // main()

} // class DateConverter