Calling a file and counting the number of words in it-please help!!

Question

* @(#)WordCounterTwo.java
* WordCounterTwo application
* @author
* @version 1.00 2007/11/17
import java.util.Scanner;
public class WordCounterTwo {
public static void main(String[] args) {
     Scanner keyboard = new Scanner(System.in);
     String fileName;
     int countWords;
     System.out.println("Please enter the name of the file: ");
     fileName = keyboard.nextLine();
     System.out.println(countWords.lastIndexOf());
}

Answer 1

I am getting error message as follows:
cannot find symbol constructor StringTokenizer() on line
I am asking the user to enter the name of a file, and the output is supposed to display the number of words in the file that chosen. I'm not sure if I am going about this right way, and not sure why I am getting the erorr messages.
* @(#)WordCounter.java
* WordCounter application
* @author
* @version 1.00 2007/11/17
import java.util.Scanner;
import java.util.StringTokenizer;
public class WordCounter {
    public static void main(String[] args) {
         String sentence;
         Scanner keyboard = new Scanner(System.in);
         StringTokenizer words = new StringTokenizer();  //line 17
         int numberWords;
         System.out.println("Please enter a sentence");
         sentence = keyboard.nextLine();
         sentence = words.nextToken();
         while (words.hasMoreTokens())
              numberWords++;
         System.out.println(numberWords);
}