(Telephone-Number Word Generator) Standard telephone keypads contain the digits zero through nine. The numbers two through nine each have three letters associated with them Fig. 1 below. Many people find it difficult to memorize phone numbers, so they use the correspondence between digits and letters to develop seven-letter words that correspond to their phone numbers. For example, a person whose telephone number is 686-2377 might use the correspondence indicated in Fig. 1 to develop the seven-letter word NUMBERS. Every seven-letter word corresponds to exactly one seven-digit telephone number. A restaurant wishing to increase its takeout business could surely do so with the number 825-3688 (i.e., TAKEOUT).

Every seven-letter phone number corresponds to many different seven-letter words, but most of these words represent unrecognizable juxtapositions of letters. Its possible, however, that the owner of a barbershop would be pleased to know that the shops telephone number, 424-7288, corresponds to HAIRCUT. A veterinarian with the phone number 738-2273 would be pleased to know that the number corresponds to the letters PETCARE. An automotive dealership would be pleased to know that the dealership number, 639-2277, corresponds to NEWCARS.

Digit	Letters	Digit	Letters	Digit	Letters
2	A B C	5	J K L	8	T U V
3	D E F	6	M N O	9	W X Y
4	G H I	7	P R S

Fig. 1 Telephone keypad digits and letters.

Write a program in Java that, given a seven-digit number, uses a Formatter object to write to a file every possible seven-letter word combination corresponding to that number. There are 2,187 (37)(37) such combinations. Avoid phone numbers with the digits 0 and 1.

Use the following test class to test your program:

import java.util.Scanner; import java.util.NoSuchElementException;

public class PhoneTest { public static void main(String[] args) { Scanner scanner = new Scanner(System.in);

Phone application = new Phone(); System.out.print( "Enter phone number (digits greater than 1 only): ");

try { application.calculate(scanner.nextInt()); } catch (NoSuchElementException elementException) { System.err.println("Error inputting data."); } } }