Q:

null pointer exception with string tokenizer

I have local String array and i try to fill it with the returned tokens from Stringtokenizer.nexttoken
when i was declaring the string array as local variable i got i warning 
Null pointer access: The variable words can only be null at this location

so i make the sting array as field in the class and i instantiate it 
like this 
 String[] words =new String [12000];

the warning disappear but i still get the same exception 
StringTokenizer st=new StringTokenizer(text);

int j=0;
while(st.hasMoreTokens())
{
  words[j++]=st.nextToken();    

}

i use callable and future to execute the part of code that contain this block 
and the exception that i get it is 
java.lang. NullPointerException
java.util.concurrent. ExecutionException:

{the code work perfectly when i use split method to get the tokens array}

A:

My problem fixed but replacing the String array with the arraylist<String>
while(st.hasMoreTokens())
    {
     words.add(st.nextToken()); 

    }

