How to change shape color dynamically?

For me, it crashed because getBackground returned a GradientDrawable instead of a ShapeDrawable.

So i modified it like this:

((GradientDrawable)someView.getBackground()).setColor(someColor);

You could modify it simply like this

GradientDrawable bgShape = (GradientDrawable)btn.getBackground();
bgShape.setColor(Color.BLACK);