How do I count the number of occurrences of a char in a String?

Source:

public class CountChars {
   public static void main(String[] args) {

      String str = "a b a c a d a e a f a g a h";

      int count = 0;
      for (int i = 0; i < str.length(); i++) {
         if (str.charAt(i) == 'a') {
            count++;
         }
      }

      System.out.println("Total a count: " + count);
   }
}

Output:

   $ java CountChars 
   Total a count: 7