CODEWITHSUNDEEP
androidandroid-asynctask
new_project
new_project

Reputation: 421

How to set image from drawables using AsyncTask in Android Studio

I am trying to perform a very simple task (loading image to ImageView in the background), but can't make it to work. Any help much appreciated.

Here is what I have so far: This is how I call the class in on create in the main thread:

 LoadImage  newImage=new LoadImage();
 newImage.execute(myImgeView);

Next I created the class:

public class LoadImage extends AsyncTask<ImageView, Void, ImageView> {

ImageView imageView;


        @Override
        protected ImageView doInBackground(ImageView... params) {
            Log.e("myTag",": Can it see this class from where I call it? Yes it does" );
     
            imageView.setImageResource(R.drawable.myNewImage);
       

            return imageView;
        }

    }

I can't figure out how to set it up correctly. It crashes saying something like: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference.

Thanks in advance for your help.

Upvotes: 0

Views: 616

Answers (3)

sebschaef
sebschaef

Reputation: 244

You should not use AsyncTask anymore, since it is deprecated like jesusd0897 already mentioned. If you need to load images from a remote resource (e.g. API) then Glide or other libraries do the job for you.

But for this simple case you don't need an asynchronous task. Just do it on the main thread in your Activity/Fragment etc:

imageView.setImageResource(R.drawable.myNewImage)

Upvotes: 0

jesusd0897
jesusd0897

Reputation: 55

AsyncTask is deprecated. For this type of operations it is recommended to use some library and make things easier: Picasso, Glide, Fresco...etc

Upvotes: 1

Kidus
Kidus

Reputation: 474

The problem lies in this code:

imageView.setImageResource(R.drawable.myNewImage);

The variable imageView can't be seen from the AsyncTask Class, the imageView you want is inside the params array so you can reference it with params[0]. So replace the above code with:

ImageView imageView = params[0];
imageView.setImageResource(R.drawable.myNewImage);
return imageView;

Upvotes: 0

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