CODEWITHSUNDEEP
javaandroidandroid-layout
Tim Stullich
Tim Stullich

Reputation: 251

AsyncTask Crashes When Adding Image To GridView

I have setup a GridView to hold some images that are loaded from an SD Card. However, there are a lot of images to be loaded and therefore I decided to run the loading and resampling tasks on a background thread using AsyncTask and adding the image into the GridView once image is done being loaded. Unfortunately whenever I run the code I run into this error:

01-01 19:49:40.239: E/AndroidRuntime(3851): FATAL EXCEPTION: main
01-01 19:49:40.239: E/AndroidRuntime(3851): java.lang.NullPointerException
01-01 19:49:40.239: E/AndroidRuntime(3851): at com.stullich.tim.woistmeinphoto.PhotoGalleryActivity.addImage(PhotoGalleryActivity.java:199)
01-01 19:49:40.239: E/AndroidRuntime(3851): at <packagename>.PhotoGalleryActivity.access$0(PhotoGalleryActivity.java:195)
01-01 19:49:40.239: E/AndroidRuntime(3851): at <packagename>.PhotoGalleryActivity$FileFetcher.onProgressUpdate(PhotoGalleryActivity.java:226)
01-01 19:49:40.239: E/AndroidRuntime(3851): at <packagename>.PhotoGalleryActivity$FileFetcher.onProgressUpdate(PhotoGalleryActivity.java:1)
01-01 19:49:40.239: E/AndroidRuntime(3851): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:618)
01-01 19:49:40.239: E/AndroidRuntime(3851): at android.os.Handler.dispatchMessage(Handler.java:99)
01-01 19:49:40.239: E/AndroidRuntime(3851): at android.os.Looper.loop(Looper.java:137)
01-01 19:49:40.239: E/AndroidRuntime(3851): at android.app.ActivityThread.main(ActivityThread.java:4514)
01-01 19:49:40.239: E/AndroidRuntime(3851): at java.lang.reflect.Method.invokeNative(Native Method)
01-01 19:49:40.239: E/AndroidRuntime(3851): at java.lang.reflect.Method.invoke(Method.java:511)
01-01 19:49:40.239: E/AndroidRuntime(3851): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
01-01 19:49:40.239: E/AndroidRuntime(3851): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
01-01 19:49:40.239: E/AndroidRuntime(3851): at dalvik.system.NativeStart.main(Native Method)

This is the code that seems to be causing the trouble:

final class FileFetcher extends AsyncTask<Void, LoadedImage, Void> 
{
  private Context mContext;

  public FileFetcher(Context context)
  {
     mContext = context;
  }

  @Override
  protected void onPreExecute()
  {
     loadImages(new File("/mnt/extSdCard/Bilder"));         
  }

  @Override
  public void onProgressUpdate(LoadedImage... value)
  {
     addImage(value);
  }

  @Override
  protected Void doInBackground(Void... rootDir) 
  {
     int i = 1;
     for (File f : directories)
     {
        File[] anImage = f.listFiles();
        if (anImage.length > 0)
        {
           Bitmap aMap = decodeSampledBitmapFromFile(anImage[0], 120, 120);
           publishProgress(new LoadedImage(aMap));
           i++;
        }
     }
     return null;

  }
}

//My addImage method
private void addImage(LoadedImage... value) 
{
  for (LoadedImage image : value) 
  {
      adapter.addPhoto(image);
      adapter.notifyDataSetChanged();
  }
}

The crash seems to happen every time the addImage method is called. A Bitmap is always returned so I have no idea where the NullPointerException can be thrown. Any help would be much appreciated since I have been sitting at this problem for quite a while.

Upvotes: 0

Views: 230

Answers (1)

Tim Stullich
Tim Stullich

Reputation: 251

I forgot to initialize my adapter in onCreate which caused the application to crash.

Upvotes: 4

Related Questions