ImageFetcherAltActivity.java

public class ImageFetcherAltActivity extends AppCompactActivity {
    class WorkerThread extends Thread {
        void fetchImage(String url) {
            handler.sendEmptyMessage(MSG_SHOW_LOADER);
            // network call to load image
            handler.obtainMessage(MSG_SHOW_IMAGE, imageBitmap).sendToTarget();
        }
    }
    
    class UIHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case MSG_SHOW_LOADER: {
                    progressIndicator.setVisibility(View.VISIBLE);
                    break;
                }
                case MSG_HIDE_LOADER: {
                    progressIndicator.setVisibility(View.GONE);
                    break;
                }
                case MSG_SHOW_IMAGE: {
                    progressIndicator.setVisibility(View.GONE);
                    imageView.setImageBitmap((Bitmap) msg.obj);
                    break;
                }
            }
        }
    }
    
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        // prepare the view, maybe setContentView, etc
        new WorkerThread().fetchImage(imageUrl);
    }
}