Question

I am looking at the documentation for animation-list and the XML layout is straight forward, but I am confused how they deal with it in the code.

In that page they have something like:

ImageView img = (ImageView)findViewById(R.id.spinning_wheel_image);
 img.setBackgroundResource(R.drawable.spin_animation);

 // Get the background, which has been compiled to an AnimationDrawable object.
 AnimationDrawable frameAnimation = (AnimationDrawable) img.getBackground();

 // Start the animation (looped playback by default).
 frameAnimation.start();

But they never reference spinning_wheel_image anywhere in the XML they show, nor the spin_animation ….the id for the spin snippet in their examples is “selected”

So I am wondering where those two references come from? And why the actual id of the XML snippet which is “selected” is never used?

Thanks!

EDIT:

I put my animations xml into a file called animation.xml

And in the code now I have this:

ImageView img = (ImageView)findViewById(R.id.spinning_wheel_image);
        img.setBackgroundResource(R.drawable.animation);

        // Get the background, which has been compiled to an AnimationDrawable object.
        AnimationDrawable frameAnimation = (AnimationDrawable) img.getBackground();

        // Start the animation (looped playback by default).
        frameAnimation.start();

Answer 1

But they never reference spinning_wheel_image anywhere in the xml they show

spinning_wheel_image is the ID of an ImageView, presumably from a layout resource used with setContentView() or a LayoutInflater.

nor the spin_animation ….the id for the spin snippet in their examples is “selected”

That is presumably a typo — there is no android:id for AnimationDrawable. At least, it is not in the documentation. The name of an animation resource is based on the filename, and the filename is spin_animation .xml.