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POWhy is changing where layout parameters are set solving my "OnClickListener not working for first item in GridView" issue?
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copied!<p>I'm using a GridView to show some images and I had a problem, as the onClickListener wasn't working for the first image. I found some other questions here at SO with the same problem, but I don't like their "correct answers", as most of them take the same approach of:</p> <ul> <li><a href="https://stackoverflow.com/questions/12746433/onclicklistener-not-working-for-first-item-in-gridview-inside-viewpager">OnClickListener not working for first item in GridView inside ViewPager</a></li> </ul> <p>Basically, instantiating the view every time getview is called. This is awful for performance and they will probably face out-of-memory issues in many devices.</p> <p>In my case, I display in the GridView the images located inside a sub-folder in the assets folder.</p> <p>My original code with the "first item" issue (actually, my original code implemented the viewholder pattern, but this one is a bit simpler and faces the same issue):</p> <pre><code> @Override public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null) { imageView = new ImageView(_activity); } else { imageView = (ImageView) convertView; } // get screen dimensions AssetManager assetManager = _activity.getAssets(); InputStream assetIn = null; try { assetIn = assetManager.open(_assets_subdir + File.separator + _filePaths.get(position)); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } Bitmap image = BitmapFactory.decodeStream(assetIn); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setLayoutParams(new GridView.LayoutParams(imageWidth, imageWidth)); imageView.setImageBitmap(image); // image view click listener imageView.setOnClickListener(new OnImageClickListener(position)); return imageView; } </code></pre> <p>My final code solving the issue:</p> <pre><code> @Override public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null) { imageView = new ImageView(_activity); imageView.setLayoutParams(new GridView.LayoutParams(imageWidth, imageWidth)); } else { imageView = (ImageView) convertView; } // get screen dimensions AssetManager assetManager = _activity.getAssets(); InputStream assetIn = null; try { assetIn = assetManager.open(_assets_subdir + File.separator + _filePaths.get(position)); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } Bitmap image = BitmapFactory.decodeStream(assetIn); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setImageBitmap(image); // image view click listener imageView.setOnClickListener(new OnImageClickListener(position)); return imageView; } </code></pre> <p>The issue was solved moving the code <code>imageView.setLayoutParams(new GridView.LayoutParams(imageWidth, imageWidth));</code>. </p> <p>But why? I'm not sure.</p> <p>I read somewhere (in SO) that it could be happening because of trying to access a view that has not been inflated yet, and the user recommended using <code>getViewTreeObserver()</code>, but I tried that approach and couldn't fix the problem.</p> <p>So, I decided to trial-and-error the code to see where to bottleneck could be and found the given solution. </p> <p>Anyone knows why is this solving the problem?</p>

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