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Android Build a Self-Destructing Message Android App Retrieving and Viewing Messages Creating a Custom List Adapter for Messages

Posted by billmei
billmei
3,540 Points

Anyone else getting a null pointer exception when loading the ImageView?

I downloaded the source files from the teacher's notes and my code matches the example code line-by-line, but for some reason whenever I run the app on my Nexus 4 (KitKat 4.4.3) it crashes and I get a null pointer exception on this line:

holder.iconImageView.setImageResource(R.drawable.ic_action_picture);

Anyone know what's going on or has experienced the same problem? I created and instantiated the static ViewHolder class as described in the video, maybe my static variable handling is wrong for some reason?

3 Answers

y0mki
y0mki
14,218 Points

Hi Bill,

I got the Null Pointer exception as well, and after a lot of research I found out that I was missing a line, which apparently doesn't cause any exceptions on Ben's emulator on this video, but some videos later he notices that he forgot it, as his ListView throws a Null Pointer exception when trying to scroll. Anyhow, here is the line that you need to add after assigning holder.iconImageView and holder.nameLabel:

holder.iconImageView = (ImageView) convertView.findViewById(R.id.messageIcon);
holder.nameLabel = (TextView) convertView.findViewById(R.id.senderLabel);
convertView.setTag(holder); // Because we use the tag on the else condition, 
                            // we need to set it here first, so that it can be used when 
                           // recycling our list using the getTag() method.

Hope this helps :innocent:

billmei
billmei
3,540 Points
billmei
billmei
3,540 Points

Ah great, this solves the problem. Thank you so much!

billmei
billmei
3,540 Points
billmei
billmei
3,540 Points