Identify a character in a string .............

Question

An exercise of a text book of java.
Count the number of letter 'a' appearing in a word. I can't do that. Here is my program, please help.
import kenya.io.InputReader;
import java.util.StringTokenizer;
public class e47{
public static void main ( String [] args ){
     System.out.println("Please type in a word ---->");
     String a = InputReader.readString();
     int r = countA(a);
     if (/*countA(a) == 0*/r == 0 ){
     System.out.println("There's no letter 'A' in this word.");
     else{
     System.out.println("The letter 'A' appears " + countA(a) + " times.");
static int countA(String a){
          StringTokenizer letterA = new StringTokenizer (a);
          int acc = 0;
          while (letterA.hasMoreTokens()){
               if ( letterA.nextToken() == "a"){
               acc = acc + 1;
          return acc;
Thanks a lot!!

Answer 1

StringTokenizer parses "words" separated by a "token" such as a space, newline, tab, whatever. That's why it's not working for your purpose.
Instead, try something like:
int count = 0;
for (int i = 0; i < a.length(); i++)
  if (a.charAt[i] == 'a')
    count++;
return count;