adding init params to list in init(ServletConfig)

Question

Trying to add init parameter names to a list in init(ServletConfig) method.

public void init(ServletConfig sc){
    try {
        super.init(sc);
        Enumeration<String> e= sc.getInitParameterNames();
        while(e.hasMoreElements()){
            list.add(e.nextElement());
        }
    } catch (ServletException e1) {
        e1.printStackTrace();
    }
}

I am getting a NullPointerException when I use this list because e.hasMoreElement() returns false. I am pretty sure that I have added the init parameters correctly in the web.xml file. What is going wrong? Please advice.

Answer 1

I think you have not intialized the list object. The list object is null.

Change the code list this:

public void init(ServletConfig sc){
   try {
      super.init(sc);
      list = new ArrrayList<String>();
      Enumeration<String> e= sc.getInitParameterNames();
      while(e.hasMoreElements()){
         list.add(e.nextElement());
      }
   } catch (ServletException e1) {
    e1.printStackTrace();
   }
}