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POLazy loading images works only sometimes, sometimes it doesn't
 

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  1. POLazy loading images works only sometimes, sometimes it doesn't
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    <p>I'm using lazy loading images based on this <a href="https://stackoverflow.com/questions/541966/android-how-do-i-do-a-lazy-load-of-images-in-listview">question</a>. I'm implementing a search function that, when the user enters a keyword, the application will do a request and parse the result using SAX and then place the data into a ListView. Sometimes the images can be loaded into ImageViews of the ListView rows but sometimes it will load only one or two images and the application crashes. </p> <p>Below is my LogCat output: </p> <pre><code>05-16 16:37:37.414: ERROR/AndroidRuntime(620): FATAL EXCEPTION: Thread-11 05-16 16:37:37.414: ERROR/AndroidRuntime(620): java.lang.NullPointerException 05-16 16:37:37.414: ERROR/AndroidRuntime(620): at com.TPLibrary.Search.ImageLoader.getBitmap(ImageLoader.java:71) 05-16 16:37:37.414: ERROR/AndroidRuntime(620): at com.TPLibrary.Search.ImageLoader.access$0(ImageLoader.java:68) 05-16 16:37:37.414: ERROR/AndroidRuntime(620): at com.TPLibrary.Search.ImageLoader$PhotosLoader.run(ImageLoader.java:173) </code></pre> <p>Below is where the errors are occuring at:</p> <pre><code>private Bitmap getBitmap(String url) { // line 68 //I identify images by hashcode. Not a perfect solution, but ok for the demo String filename = String.valueOf(url.hashCode()); // line 71 File f = new File(cacheDir, filename); //from SD cache Bitmap b = decodeFile(f); if (b != null) return b; //from web try { Bitmap bitmap = null; InputStream is = new URL(url).openStream(); OutputStream os = new FileOutputStream(f); Utils.CopyStream(is, os); os.close(); bitmap = decodeFile(f); return bitmap; } catch (Exception ex){ ex.printStackTrace(); return null; } } class PhotosLoader extends Thread { public void run() { try { while(true) { //thread waits until there are any images to load in the queue if (photosQueue.photosToLoad.size() == 0) synchronized(photosQueue.photosToLoad) { photosQueue.photosToLoad.wait(); } if (photosQueue.photosToLoad.size() != 0) { PhotoToLoad photoToLoad; synchronized(photosQueue.photosToLoad) { photoToLoad=photosQueue.photosToLoad.pop(); } Bitmap bmp = getBitmap(photoToLoad.url); // line 173 cache.put(photoToLoad.url, bmp); Object tag = photoToLoad.imageView.getTag(); if (tag != null &amp;&amp; ((String)tag).equals(photoToLoad.url)){ BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad.imageView); Activity a = (Activity)photoToLoad.imageView.getContext(); a.runOnUiThread(bd); } } if (Thread.interrupted()) break; } } catch (InterruptedException e) { //allow thread to exit } } } </code></pre> <p><strong>EDIT</strong><br> I have tracked down the <code>NullPointerException</code> that comes from the <code>PhotoToLoad</code> class below:</p> <pre><code>private class PhotoToLoad { public String url; public ImageView imageView; public PhotoToLoad(String u, ImageView i) { url = u; imageView = i; } } </code></pre> <p>How can I solve the problem?</p>
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