Escribir en un EditText con formato de tarjeta de crédito

public static void handleCardNumber(EditText editText){
    editText.addTextChangedListener(new TextWatcher() {
        int prevL = 0;
        
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            prevL = editText.getText().toString().length();
        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void afterTextChanged(Editable editable) {
            if(!editable.toString().equals(lastString)){
                String str = editable.toString().replace(" ", "");
                String newString = "";
                int index = 0;

                for(int i = 0; i < str.length(); i++){
                    if(i % 4 == 0 && i > 0){
                        newString += " ";
                    }
                    newString += str.charAt(i);
                }