How Do I Get A Bitmap From Asynctask And Set It To My Image

I am trying to use an AsyncTask to convert an image URL to a bitmap in order to set it to an image. I don't understand how to get the bitmap out of the AsyncTask so that I can set

Solution 1:

Simply define final ImageView variable linked to the view you want to fill with the Bitmap:

//inside some method e.g. onCreate()
     final ImageView imageView = (ImageView) findViewById(R.id.myPrettyImage);

     newAsyncTask<String, Void, Bitmap>() {
        @OverrideprotectedBitmapdoInBackground(String... params) {
            /* here's your code */
        }

        @OverrideprotectedvoidonPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);

            imageView.setImageBitmap(bitmap);
        }
    }.execute(/*your params*/);

Or you can create ImageView field in your AsyncTask extended task:

privateclassExtendedAsyncTaskextendsAsyncTask<String, Void, Bitmap> {
    privateImageView[] views;

    publicvoidExtendedAsyncTask(ImageView[] views) {
        this.views = views;
    }

    @OverrideprotectedBitmapdoInBackground(String... params) {
        /* your code here */
    }

    @OverrideprotectedvoidonPostExecute(Bitmap bitmap) {
        super.onPostExecute(bitmap);
        for (ImageViewview: views) {
            view.setImageBitmap(bitmap);
        }
    }
}

and use it:

ExtendedAsyncTaskaTask=newExtendedAsyncTask(newImageView[]{myImageView1, myImageView2, myImageView3});
aTask.execute(/*some params*/);

Solution 2:

This has to be a fairly common task. Why is it so difficult?

I'd really recommend you take a look into the Android Volley library. It's made to abstract away all this AsyncTask boilerplate code. Here's a very nice example of how to set an image bitmap

ImageLoader imageLoader = AppController.getInstance().getImageLoader();
 
// If you are using normal ImageView
imageLoader.get(Const.URL_IMAGE, newImageListener() {
 
    @Override
    publicvoidonErrorResponse(VolleyError error) {
        Log.e(TAG, "Image Load Error: " + error.getMessage());
    }
 
    @Override
    publicvoidonResponse(ImageContainer response, boolean arg1) {
        if (response.getBitmap() != null) {
            // load image into imageview
            imageView.setImageBitmap(response.getBitmap());
        }
    }
});

You can read more from here: http://www.androidhive.info/2014/05/android-working-with-volley-library-1/