Question

I have a function which fetches a certain website’s HTML code. Eventually that function will return the whole page as an array. I am trying to save the page in another array, but it will always throw an exception (ArrayIndexOutOfBoundsException) for some reason.

I am not sure if I am just missing something elementary or if it’s more than just that. To give you some of my code:

  protected String[] doInBackground(String... login)
        {
            String[] page = new String[1024];
            try {
                page = executeHttpGet(); //THIS IS WHERE IT FAILS
            } catch (Exception e) {
                page[0] = "Error";
            }
            return page;
        }

public String[] executeHttpGet() throws Exception {
         URL u;
         InputStream is = null;
         DataInputStream dis;
         String s;
         int i = 0;
         String[] page = new String[1024];
         addSecurityException();
         Authenticator.setDefault(new MyAuthenticator(activity));
         try {
            u = new URL("https://myurl.com");
            is = u.openStream();        
            dis = new DataInputStream(new BufferedInputStream(is));
            while ((s = dis.readLine()) != null) {
                if (s.toString().length() > 10)
                    {
                    page[i] = s.toString();
                    i++;
                    }
            }
        } catch (IOException ioe) {

        }
         finally {
            try {
               is.close();
            } catch (IOException ioe) {

            }
        } 
         return page;
    }
    }

Does anyone have any ideas why I am not able to assign the returned array to the array in doInBackground()? Help would be greatly appreciated.

Answer 1

1. Your catch-blocks are empty, which is a terrible idea, because you’ll get no information when something goes wrong.
2. You don’t need to initialize page on its declaraton, when you re-assign it two lines below (you’ll have to change the catch-block to create a new array, ‘though).
3. Have you checked that your URL doesn’t return more than 1024 lines?
4. You don’t need s.toString() when s is a String, because it will just return s.
5. When analyzing an exception, you should look at the whole stacktrace to find out where exactly the problem occurs.
6. When asking about an exception you should post the whole stacktrace!

When you have an unspecified number of elements List is a more flexible and easier-to-use alternative to arrays. Generally speaking, arrays are quite low-level and there’s barely a reason to use them directly (they are very useful for building List implementations).