How to programmatically set backgroundTint of FloatingActionButton with ColorStateList?

use this:

fab.setBackgroundTintList(ContextCompat.getColorStateList(getApplicationContext(), R.color.purple_200));

Cheers!

Since setBackgroundTintList is only supported in API 21+ you can use ViewCompat.

ViewCompat.setBackgroundTintList(
    fab, 
    ContextCompat.getColorStateList(
        getApplicationContext(),
        R.color.purple_200
    )
);