Creating AsyncTask in Android

Explains how to create an asynctask which allows the image file loading to be done in a background thread.

Part 2 – Addresses the issue with the bitmaps being loaded from the filesystem in the UI thread by creating asynctask in android which in effect creates a background thread to do the file loading.

Steps

Create the AsyncTask Class

public class BitmapWorkerTask extends AsyncTask<File, Void, Bitmap> {

    WeakReference<ImageView> imageViewReferences;

    public BitmapWorkerTask(ImageView imageView) {
        imageViewReferences = new WeakReference<ImageView>(imageView);
    }

    @Override
    protected Bitmap doInBackground(File... params) {
        return BitmapFactory.decodeFile(params[0].getAbsolutePath());
    }

    @Override
    protected void onPostExecute(Bitmap bitmap) {
        if(bitmap != null && imageViewReferences != null) {
            ImageView viewImage = imageViewReferences.get();
            if(viewImage != null) {
                viewImage.setImageBitmap(bitmap);
            }
        }
    }
}

Call the AsyncTask

BitmapWorkerTask workerTask = new BitmapWorkerTask(holder.getImageView());
       workerTask.execute(imageFile);

Run the App