public class Telephone {
/*  This application lets a user enter a letter from the telephone \
	and returns the corresponding number.
*/

	public static void main(String args[]) {
		
             String	letter;
	     char	aChar;
	     String prompt="Enter a letter on the telephone (Q or Z to quit):";

	     System.out.print(prompt);
	     letter = Keyboard.in.readString();
             if (letter !=null) 
	          aChar = letter.toUpperCase().charAt(0);
             else aChar=' ';
			
	     while ((aChar != 'Q') && (aChar != 'Z')) {
			
			if ("ABC".indexOf(aChar) != -1) 
				Telephone.report(aChar, 2);
				
			else if ("DEF".indexOf(aChar) != -1) 
				Telephone.report(aChar, 3);
			
			else if ("GHI".indexOf(aChar) != -1) 
				Telephone.report(aChar, 4);
			
			else if ("JKL".indexOf(aChar) != -1) 
				Telephone.report(aChar, 5);
			
			else if ("MNO".indexOf(aChar) != -1) 
				Telephone.report(aChar, 6);	
			
			else if ("PRS".indexOf(aChar) != -1) 
				Telephone.report(aChar, 7);
				
			else if ("TUV".indexOf(aChar) != -1) 
				Telephone.report(aChar,8);
				
			else if ("WXY".indexOf(aChar) != -1) 
				Telephone.report(aChar, 9);
			
			
			else {
				System.out.println("Invalid letter.");
			}
 
                        System.out.print(prompt);
    		        letter = Keyboard.in.readString();
                        if (letter !=null) 
	                   aChar = letter.toUpperCase().charAt(0);
                        else aChar=' ';
			   aChar = letter.charAt(0);

	     }
	     System.out.println();	
	     System.out.println("Have a nice day!");
			
	}
	
	private static void report (char aChar, int value) {
		
		System.out.print("The letter " + aChar + " corresponds to ");
		System.out.print(value);
		System.out.println(" on the telephone.");
		System.out.println();

	}		
}