Question

Modify Java program to accept a telephone number with any number of the letters, using the if else loop. 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.

Answer 1

Please follow the code and comments for description :

CODE :

import java.util.HashMap; // required imports for the code to run

import java.util.Map;
import java.util.Scanner;

public class Telephone { // calss to run the methods

public static void main(String[] args) { // driver method
  
Scanner sc = new Scanner(System.in); // scanner class to get the data from the user

System.out.print("Enter the Telephone letters : "); // prompt the user to enter the data
String input = sc.nextLine(); // get the data
String lowerInput = input.toLowerCase(); // converting the data to lowercase

TeleNumProcessor NumProcessor = new TeleNumProcessor(lowerInput); // creating an object ofr the class and pass the data
String result = NumProcessor.process(); // call the method and save the result

System.out.println("---------------------------------------------------"); // print the data to console
System.out.println("The Entered Telephone letters are : " + input);
System.out.println("The Phone number is : " + result);
System.out.println("---------------------------------------------------");
}

}

class TeleNumProcessor { // class that gets the numbers for the input

Map match = new HashMap<>(); // map that stores the matching numbers
String strToProcess; // required initialisations

public TeleNumProcessor(String strToProcess) { // method that takes the input and returns the number string
this.strToProcess = strToProcess;
match.put("[a-c]", "2"); // saving the data to the map for the patterns
match.put("[d-f]", "3");
match.put("[g-i]", "4");
match.put("[j-l]", "5");
match.put("[m-o]", "6");
match.put("[p-s]", "7");
match.put("[t-v]", "8");
match.put("[w-z]", "9");
}

public String process() { // method to process the input data

if (!"2".equals(strToProcess)) { // checking if the input is 2 or not
match.forEach((regex, replacement) -> { // method to check for the regex pattern matcher
strToProcess = strToProcess.replaceAll(regex, replacement); // replace the dat and place it to the string
});
}
return strToProcess.substring(0, 3) + "-" + strToProcess.substring(3, 7); // return the formatted data
}
}

OUTPUT :

Enter the Telephone letters : fewfwef
The Entered Telephone letters are : fewfwef
The Phone number is : 339-3933