How do I count the number of words in a string?

Question

I need to count the number of words and I am assuming the correct way to do it is by calculating the number of times that the previous character in a string is not a letter

Answer 1

   if (string.charAt(i-1) == alphabets.charAt(j)) {
       counter++;
   }

You are incrementing the counter if the character is some alphabet character. You should increment it if it is no alphabet character.

Answer 2

Your suggestion to use a regex like "[A-Za-z]" would work fine. In a split command, you'd split on the inverse, like:

String[] words = "Example test: one, two, three".split("[^A-Za-z]+");

EDIT: If you're just looking for raw speed, this'll do the job more quickly.

public static int countWords(String str) {
    char[] sentence = str.toCharArray();
    boolean inWord = false;
    int wordCt = 0;
    for (char c : sentence) {
        if (c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z') {
            if (!inWord) {
                wordCt++;
                inWord = true;
            }
        } else {
            inWord = false;
        }
    }
    return wordCt;
}