supportパッケージAlertDialog Button色の変更

Button positionButton = mDialog.getButton(AlertDialog.BUTTON_POSITIVE);
            positionButton.setTextColor(ContextCompat.getColor(NewPaymentActivity.this, R.color.red_tips));
            Button negativeButton = mDialog.getButton(AlertDialog.BUTTON_NEGATIVE);
            negativeButton.setTextColor(ContextCompat.getColor(NewPaymentActivity.this, R.color.gray9));