Java null pointer exception while using Async Task for lazy load of images

Question

I was trying to use AsyncTask for lazy load of images in the adapter.

        public View getView(final int position,View convertView,ViewGroup parent){

    Bitmap userAvatarStream = null,podIconStream = null ;
    Bitmap podIconStream1 = null;
    Bitmap podIconStream2 = null;

    View v = convertView;

    if (v == null){
        LayoutInflater li = (LayoutInflater)c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = li.inflate(R.layout.user_list_item,null);

    }

 user = users.get(position);    


    if(user != null){

        URL userImageURL,podImageURL = null;

        //TextView tk = (TextView)v.findViewById(R.id.text_key);
        TextView firstname = (TextView)v.findViewById(R.id.follower_fullname);
        ImageView user_avatar = (ImageView)v.findViewById(R.id.follower_user_avatar);

        new LoadImage(user_avatar).execute();

TextView userProfileClick = (TextView)v.findViewById(R.id.follower_fullname);

        userProfileClick.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                String uID = user.getID();


                //Pass User id to another Intent(UserProfile)
                Intent userIntent = new Intent(activity,UserProfileMainActivity.class);
                userIntent.putExtra("userID",uID);
                activity.startActivity(userIntent);

            }
            });         

        ListView podlist = (ListView)v.findViewById(R.id.user_list); 

        ArrayList<Cr> List = new ArrayList<Cr>();

        for(Crb c : user.crList){
            List.add(c);
        }


        //new LoadImage(user_avatar).execute(); 
        UserFollowingPodListAdapter podadapter = new UserFollowingPodListAdapter(activity, R.layout.user_crumbs_pod_list_item,crumbsUpList,activity);
        podlist.setAdapter(podadapter);

    }
    return v;
} 

class LoadImage extends AsyncTask<String, Void, String>{

    private ImageView imv;
    private String path;
Bitmap userAvatarStream = null ;
final Bitmap podIconStream = null;

ProgressDialog dialog;

    @Override 
    protected void onPreExecute(){
        //Setting all the variables by getting the ids from the layout


    return;

    }


    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub


        URL userImageURL,podImageURL = null;

        try {
            userImageURL = new URL(user.imageUrl);
            if (user == null)
                return null;
            userAvatarStream = BitmapFactory.decodeStream(userImageURL.openConnection().getInputStream());
            if (userAvatarStream == null)
                return null;




        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;

    }

     @Override

     protected void onPostExecute(String result){
         user_avatar.setImageBitmap(userAvatarStream);

         return;

     }

}

}

I got a Java Null Poitner Exception at onPostExecute.

I've debugged the code and userAvatarStream is not null. Have tried if/else, try/catch in trying to figure out where the null exception is happening, and figured out where: user_avatar.setImageBitmap(userAvatarStream); But, don't know why it is happening or how to remove it. Any help will be much appreciated.

Edit:

TextView firstname = (TextView)v.findViewById(R.id.follower_fullname);
            ImageView user_avatar = (ImageView)v.findViewById(R.id.follower_user_avatar);

user_avatar is null, it shouldn't be null. It seems no where you assigned any thing to user_avatar. — kosa
– kosa, Commented Feb 7, 2012 at 17:10
Where are you instantiating the "user_avatar" member? Post that code so that we can see where/when you're doing it. Could be helpful. — hooked82
– hooked82, Commented Feb 7, 2012 at 17:11
Follow it down the line: are you certain that there's an ImageView with id follower_user_avatar in your layout? — Brian Dupuis
– Brian Dupuis, Commented Feb 7, 2012 at 17:21
Yes. And, the code works if I remove asynctask from the code and not use any threading — Hick
– Hick, Commented Feb 7, 2012 at 17:25

ahodder · Accepted Answer · 2012-02-07 20:52:30Z

1

In agreement with the commentors, you need to actually instantiate the user_avatar for it to be usable. You open the stream to pull the avatar, but never actually do anything with it.

Edit:

View v = LayoutInflater.from(context).inflate(R.layout.mybigdamnlayout, null);

Use this over SystemService. It is much more effective (by effective I mean I have never had a NPE this way).

edited Feb 7, 2012 at 20:52

answered Feb 7, 2012 at 17:15

ahodder

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5 Comments

ahodder Over a year ago

@Hiccup When are you calling the task? In onCreate(Bundle)? Try in onResume(). I don't think that should matter, but it may.

Hick Over a year ago

This is an adapter and not an activity.

ahodder Over a year ago

Better, could you just post the whole adapter.getView(...) code?

ahodder Over a year ago

Don't use Context.getSystemService. Instead you somthing like what I posted above.

Hick Over a year ago

Did the change. Error still continues.

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