Question

To make telephone numbers easier to remember, some companies use letters to show their telephone number. For example, using letters, the telephone number 438-5626 can be shown as GET LOAN. In some cases, to make a telephone number meaningful, companies must see more than seven letters. For example, 255-5466 can be displayed as CALL HOME, which uses eight letters.

Write a program that prompts the user to enter a telephone expressed in letters and outputs the corresponding telephone number in digits. If the user enters more than seven letters, then process only the first seven letters. Also output the - (hyphen) after the third digit. Allow the user to use both uppercase and lowercase letters as well as spaces between words.

Modify to accept a telephone number with any number of letters. The output should display a hyphen after the first 3 digits and subsequently a hyphen (-) after every four digits. Also, modify the program to process as many telephone numbers as the user wants.

* Java program free from syntax, logic and run time errors

* Used appropriate String and Character methods to handle blank spaces, digits, letters and others.

* Code optimisation: no unnecessary variables, if statements and counters

*(at least one with blank spaces etc.) Descriptive block and inline comments included.

Answer 1

import java.util.Scanner;

public class PhoneNumber {
public static void main(String args[]) {
  
String phoneNumber;
char phoneDigit;
Scanner scan = new Scanner(System.in);
  
for(;;)
{
System.out.print("\nEnter a phone number in letters only (or press 1 to exit): ");
phoneNumber = scan.next();
  
if(phoneNumber.equals("1"))
{
break;
}
for(int i = 0; i < 7; i++)
{
phoneDigit = phoneNumber.charAt(i);

if(i == 3)
System.out.print("-");
if(phoneDigit >= 'A' && phoneDigit <= 'Z' || phoneDigit >= 'a' && phoneDigit <= 'z')
{
switch(phoneDigit)
{
case 'A':
case 'a':
case 'B':
case 'b':
case 'C':
case 'c':
System.out.print("2");
break;
case 'D':
case 'd':
case 'E':
case 'e':
case 'F':
case 'f':
System.out.print("3");
break;
case 'G':
case 'g':
case 'H':
case 'h':
case 'I':
case 'i':
System.out.print("4");
break;

case 'J':
case 'j':
case 'K':
case 'k':
case 'L':
case 'l':
System.out.print("5");
break;
case 'M':
case 'm':
case 'N':
case 'n':
case 'O':
case 'o':
System.out.print("6");
break;
case 'P':
case 'p':
case 'Q':
case 'q':
case 'R':
case 'r':
case 'S':
case 's':
System.out.print("7");
break;

case 'T':
case 't':
case 'U':
case 'u':
case 'V':
case 'v':
System.out.print("8");
break;

case 'W':
case 'w':
case 'X':
case 'x':
case 'Y':
case 'y':
case 'Z':
case 'z':
System.out.print("9");
break;   
}
}
}
}
}
}

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