package programming;

import java.text.DecimalFormat;

public class NNNumberToWordExample {
	// array of string type for one digit numbers
	private static final String[] doubleDigits = { "", " Ten", " Twenty", " Thirty", " Forty", " Fifty", " Sixty",
			" Seventy", " Eighty", " Ninety" };
	// array of string for two digits numbers
	private static final String[] singleDigit = { "", " One", " Two", " Three", " Four", " Five", " Six", " Seven",
			" Eight", " Nine", " Ten", " Eleven", " Twelve", " Thirteen", " Fourteen", " Fifteen", " Sixteen",
			" Seventeen", " Eighteen", " Nineteen" };

	// converts a number to words (up to 1000)
	private static String convertUptoThousand(int number) {
		String soFar;
		if (number % 100 < 20) {
			soFar = singleDigit[number % 100];
			number = number / 100;
		} else {
			soFar = singleDigit[number % 10];
			number = number / 10;
			soFar = doubleDigits[number % 10] + soFar;
			number = number / 10;
		}
		if (number == 0)
			return soFar;
		return singleDigit[number] + " Hundred " + soFar;
	}

	// converts a long number (0 to 999999999) to string
	public static String convertNumberToWord(long number) {
		// checks whether the number is zero or not if number is zero return zero
		if (number == 0) {
			return "zero";
		}
		// convert long value to string
		String num = Long.toString(number);
		// for creating a mask padding with "0"
		String pattern = "000000000000";
		/**
		 * Convert to DecimalFormat using the specified pattern and also provides the
		 * symbols to default locale
		 */
		DecimalFormat decimalFormat = new DecimalFormat(pattern);
		// format a number of the DecimalFormat
		num = decimalFormat.format(number);
		/**
		 * format: XXXnnnnnnnnn the subString() method returns a new string that is a
		 * substring of this string the substring begins at the specified beginIndex and
		 * extends to the character at index endIndex - 1 the parseInt() method converts
		 * the string into integer
		 */
		int billions = Integer.parseInt(num.substring(0, 3));
		// format to: nnnXXXnnnnnn
		int millions = Integer.parseInt(num.substring(3, 6));
		// format to: nnnnnnXXXnnn
		int hundredThousands = Integer.parseInt(num.substring(6, 9));
		// format to: nnnnnnnnnXXX
		int thousands = Integer.parseInt(num.substring(9, 12));

		String tradBillions;

		switch (billions) {
		case 0:
			tradBillions = "";
			break;
		case 1:
			tradBillions = convertUptoThousand(billions) + " Billion ";
			break;
		default:
			tradBillions = convertUptoThousand(billions) + " Billion ";
		}

		String result = tradBillions;
		String tradMillions;
		switch (millions) {
		case 0:
			tradMillions = "";
			break;
		case 1:
			tradMillions = convertUptoThousand(millions) + " Million ";
			break;
		default:
			tradMillions = convertUptoThousand(millions) + " Million ";
		}
		result = result + tradMillions;

		String tradHundredThousands;
		switch (hundredThousands) {
		case 0:
			tradHundredThousands = "";
			break;
		case 1:
			tradHundredThousands = "One Thousand ";
			break;
		default:
			tradHundredThousands = convertUptoThousand(hundredThousands) + " Thousand ";
		}
		result = result + tradHundredThousands;

		String tradThousand;
		tradThousand = convertUptoThousand(thousands);
		result = result + tradThousand;

		// removing extra space if any
		return result.replaceAll("^\\s+", "").replaceAll("\\b\\s{2,}\\b", " ");
	}

	public static void main(String args[]) {
		// Test cases to convert number to words
		System.out.println(convertNumberToWord(5));
		System.out.println(convertNumberToWord(89));
		System.out.println(convertNumberToWord(656));
		System.out.println(convertNumberToWord(1301));
		System.out.println(convertNumberToWord(13512));
		System.out.println(convertNumberToWord(567319));
		System.out.println(convertNumberToWord(90908890));
		System.out.println(convertNumberToWord(2000000000));
		System.out.println(convertNumberToWord(569999999));
		System.out.println(convertNumberToWord(3233000000L));
		System.out.println(convertNumberToWord(5000000));
		System.out.println(convertNumberToWord(333333333));
		System.out.println(convertNumberToWord(5000400));
		System.out.println(convertNumberToWord(600000));
		System.out.println(convertNumberToWord(4000000));
	}
}

Five
Eighty Nine
Six Hundred Fifty Six
One Thousand Three Hundred One
Thirteen Thousand Five Hundred Twelve
Five Hundred Sixty Seven Thousand Three Hundred Nineteen
Ninety Million Nine Hundred Eight Thousand Eight Hundred Ninety
Two Billion 
Five Hundred Sixty Nine Million Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine
Three Billion Two Hundred Thirty Three Million 
Five Million 
Three Hundred Thirty Three Million Three Hundred Thirty Three Thousand Three Hundred Thirty Three
Five Million Four Hundred 
Six Hundred Thousand 
Four Million