Chapter 6 Exercise 20, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*6.20 (Count the letters in a string) Write a method that counts the number of letters in a string using the following header: public static int countLetters(String s) Write a test program that prompts the user to enter a string and displays the num- ber of letters in the string.

import java.util.Scanner;
 
public class ProgrammingExercise6_20 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
  System.out.print("Enter a string: ");
  String s = input.nextLine();
 
  System.out.println("The number of letters is " + countLetters(s));
 
 }
 
 public static int countLetters(String s) {
 
  int countLetter = 0;
 
  for (int i = 0; i < s.length(); i++) {
   if (isLetter(s.charAt(i))) {
    countLetter++;
   }
  }
 
  return countLetter;
 }
 
 public static boolean isLetter(char ch) {
 
  return ((ch <= 'z' && ch >= 'a') || (ch <= 'Z' && ch >= 'A'));
 
 }
 
}