xxxxxxxxxx
List<Integer> imgList = Arrays.asList(R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4); // add your images names
Random rand = new Random();
int pickedImg = rand.nextInt(imgList.size()); // picking random number between 0 to list size - 1
ImageView imageView = findViewById(R.id.your_image);
imageView.setImageDrawable(ContextCompat.getDrawable(requireContext(), imgList.get(pickedImg)));