Why is this causing a runtime error? (finding word count of a string using HashMap)

import java.util.HashMap;
import java.util.Iterator;

class L6ex1pt2 {
    String line = "When I was there, it was there"; //works for Strings with all unique words 
                                                    //but not for Strings with repeated words (like this)

    public static void main(String[] args) {
        L6ex1pt2 test = new L6ex1pt2();
        HashMap<String, Integer> hash = new HashMap<String, Integer>();
        hash = test.countWords(test.line);

    }

    public String[] words(String s) {
        String[] words = s.split("\\s+");           
        return words;
    }

    public HashMap<String, Integer> countWords(String s) {
        HashMap<String, Integer> wordCount = new HashMap<String, Integer>();
        String[] werds = words(s);
        for (String w: werds) {
            if (wordCount.containsKey(w)) {
                wordCount.put(w, wordCount.get(s)+1);
            } else {
                wordCount.put(w, 1);                
            }
        }
        return wordCount;
    }

}

Throws this exception:

Exception in thread "main" java.lang.NullPointerException at L6ex1pt2.countWords(L6ex1pt2.java:24) at L6ex1pt2.main(L6ex1pt2.java:10)

Line 25

wordCount.put(w, wordCount.get(s)+1);

should be

wordCount.put(w, wordCount.get(w)+1);

Since s contains the whole string and not the word you expect for the hashmap key.