NumberInLetters.java

import javax.swing.*;

public class NumberInLetters {

    /**
    *   Program:    NumberInLetters.java
    *   Purpose:    Display a number between 0 and 100 (inclusive) in English words
    *   Creator:    Chris Clarke
    *   Created:    09.08.2014
    */

    public static void main(String[] args) {
        String num1 = JOptionPane.showInputDialog("Enter number between 0 and 100.");
        int number = Integer.parseInt(num1);
        System.out.println(getNumberWord(number));
    } // end main()

    public static String getNumberWord(int num) {

        switch (num) {
            case 0: return "Zero";
            case 1: return "One";
            case 2: return "Two";
            case 3: return "Three";
            case 4: return "Four";
            case 5: return "Five";
            case 6: return "Six";
            case 7: return "Seven";
            case 8: return "Eight";
            case 9: return "Nine";
            case 10: return "Ten";
            case 11: return "Eleven";
            case 12: return "Twelve";
            case 13: return "Thirteen";
            case 14: return "Fourteen";
            case 15: return "Fifteen";
            case 16: return "Sixteen";
            case 17: return "Seventeen";
            case 18: return "Eighteen";
            case 19: return "Nineteen";
            default: return twentyPlus(num);
        } // end switch
    } // end getNumberWord()

    public static String twentyPlus(int num) {

        String word = "";
        int tens = num / 10;
        int units = num % 10;

        switch (tens) {
            case 2: word="Twenty "; break;
            case 3: word="Thirty "; break;
            case 4: word="Forty "; break;
            case 5: word="Fifty "; break;
            case 6: word="Sixty "; break;
            case 7: word="Seventy "; break;
            case 8: word="Eighty "; break;
            case 9: word="Ninety "; break;
            case 10: return "A Hundred";
            default: return "Number not recognised";
        } // end switch

        if (units>0) {
            word+=getNumberWord(units);
        } // end if

        return word;
    } // end twentyPlus()
} // end class NumberInLetters