Hello, I have a code I did in eclipse that has numbers and letters from a dialpad that reads a letter and displays its corresponding digit. I just have a question listed down below the code I will paste.

import java.util.Scanner;

public class KeyPad { public static void main (String[ ] args) { //declare variables & Scanner object char letter; int number = 0; Scanner input = new Scanner(System.in); //display & ask System.out.println(" Welcome to the Phone Key Pad translator!"); System.out.print(" Enter one uppercase letter: "); //read letter letter = input.next().toUpperCase().charAt(0); //switch statment to process corresponding number on key pad switch(letter) { case 'A': case 'B': case 'C': number = 2; break; case 'D': case 'E': case 'F': number = 3; break; case 'G': case 'H': case 'I': number = 4; break; case 'J': case 'K': case 'L': number = 5; break; case 'M': case 'N': case 'O': number = 6; break; case 'P': case 'Q': case 'R': case 'S': number = 7; break; case 'T': case 'U': case 'V': number = 8; break; case 'W': case 'X': case 'Y': case 'Z': number = 9; break; default: System.out.println(" " + letter + " is an invalid input"); }//end of switch //display corresponding letter System.out.println(""); System.out.println("The corresponding number is: " + number); System.out.println(""); }//end of main }//end of the class

This is the Question:

Testing: (Describe how you test this program)