Android : How to set an image to an imageview from a url programatically

I have an image url coming from my rest API. Now I want to set it to an imageview when activity is loading. Below is how I get the bean from the rest api and then get the URL out of it.

Message message=new Message();
String imageUrl=message.getImageUrl();

I get Message object from my database and image url is include in that Message object.

Then I used Url object to get that image url.

URL url = null;
try {
     url = new URL(imageUrl);
     Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
     contentImageView.setImageBitmap(bmp);
} catch (Exception e) {
     e.printStackTrace();
}

I used above codes to load image to an imageview object which is contentImageView.

But still I cannot load this image to imageview, Nothing is getting loaded.

have any ideas?