Java Problem 25

So I picked the last problem first. And here's my take...

/**
 * 25.Write a Java class called CountWords, which defines 
 * a main() method that asks the user to  
 * enter a String s, and displays the number of words in s. 
 * A word is delimited by one or many space 
 * characters. You MUST NOT not use any of the methods defined in 
 * the String class other than
 * charAt() and length(). In addition, you MUST NOT use the 
 * StringTokenizer class.
 *
 * @author obispo
 */
import javax.swing.*;
import java.text.*;

class CountWords {
 public static void main( String[] args ) {
  String s;
  int words = 0, index, len, notspace = 0;

  s = JOptionPane.showInputDialog(null, "Enter string:");
  s += " ";
  len = s.length();
  for (index = 0; index < len; index++) {
   if (s.charAt(index) != ' ') {
    notspace = 1;
   } else {
    if (notspace == 1) words++;
    notspace = 0;
   }
  }   
  
  JOptionPane.showMessageDialog(null, "Word Count: " + words);
 }
}