i would like to Display an image gallery but from "assets/images" folder not from the phone storage.
The question is not clear, if you want to load a single image from assets, then you can do it this way.
//read image from asset
InputStream is = getAssets().open("image.jpg");
// create a drawable
Drawable drawable = Drawable.createFromStream(is, null);
//find reference to your imageview and set drawable
ImageView i=(ImageView)findViewById(R.id.image_id);
i.setImageDrawable(drawable);