Right way to keep objects in camera

Newbie & Debugging Questions
#1

Im trying to keep my touchpad on screen when moving camera, im doing this after camera moves on the render() loop

        stage.getCamera().update();
        touchpad.setBounds((stage.getCamera().position.x-(Gdx.graphics.getWidth()/2))+15,(stage.getCamera().position.y-(Gdx.graphics.getHeight()/2))+15,100,100);

But im thinking this is not the right way, is there any “layer” class where i can add my UI objects and then make it move together with my camera on a simple way?

Hope some help, and sorry for any english mistakes.

ED: Im using LibGDX forgot to say it.