Returning vector and null pointer exception

Question

Hi, I'm writing a mailing program which so far is working fine, but I have now run into a problem which is completely throwing me. My mailer needs to be able to load multiple attachments - and also to be able to deal with an HTML text which contains multiple images. In each case, what I'm trying to do is to put the attachments and the images into separate vectors and process them through an iterator. The logic, at least, I hope is correct.
I can get my code to compile but it keeps throwing a null pointer exception a runtime. Somehow, I just can't get it to pass the vector from one part of the code to another.
Can anyone help me? I've tried various things, none of which seem to work. My code, as it stands, is posted in a skeletal form below.
Thanks for any ideas:
public class MailSender
   // declare various variables, including:   
     Vector embeddedImages;
     String HTMLString;
    public MailSender()
        setup();
    private void setup()
     //this part of the program sets up the various parts of the mail  (to, from, body etc)    
      HTMLString = "blah blah blah";  //sample HTMLString   
       Vector embeddedImages = null; //is this correct?
        if (HTMLString.length() > 0)
            processHTMLString(HTMLString);
     private String procesHTMLString(String htmlText)
        Vector embeddedImages = new Vector(); // I construct my vector here, is this correct?
        //Here I process the HTML string to extract the images
        //get the file path of the image and pass it to the vector
        addToVector(imageFile);
        return HTMLString;
    public Vector addToVector(String imageFile)
        embeddedImages.add(imageFile);
        return embeddedImages;
    private void send()
        //this part does the sending of the mail
        //at some part in this method I need to get at the contents of the vector:
        //but this part isn't working, I keep getting a null pointer exception
        Iterator singleImage = embeddedImages.iterator();
        while (singleImage.hasNext())
    public static void main(String[] args)
        MailSender ms = new MailSender();
        ms.send();
        System.out.println("MailSender is done ");
}

Answer 1

>>>>while they don't have a clue on how the language and/or programming in general works.
Thank you, salpeter, for your esteemed estimation of my programming competence.
>>>What I'm wondering is: how come people always start building applications... blah blah
The reason being, is that it happens to be my job.
OK, I'm perhaps slower than most and there are things I don't yet understand but I get paid probably about a tenth of what you do (and maybe even less). I regard it as a kind of apprenticeship which, after a past life having spent twenty years packing crates in a warehouse, is worth the sacrifice. Six months ago I'd never written a line of code in my life and everything I've learned since has been from books, the good people in these forums, and a lot of patient trial and error. It's hard work, but I'll get there.
I say this, only as encouragement to anyone else who is trying to learn java and hasn't had the benefit of IT training at school and a four year computing course at university paid for by the parents, and for whom the prohibitive cost (in both time and money) of most java courses would never allow them to get on this ladder.
Excuse my somewhat acerbic posting, but comments such as yours tend to provoke...
Thank you EverNewJoy for explaining this to me. I haven't had time yet to try it out, but at least the concept now is clear to me.