Escribir en un EditText tipo tarjeta de crédito

private TextWatcher getCreditCardInputWatcher(final EditText editText) {
        return new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
            }

            @Override
            public void afterTextChanged(Editable s) {
                String source = s.toString();
                int length = source.length();

                StringBuilder stringBuilder = new StringBuilder();
                stringBuilder.append(source);

                if (length > 0 && length % 5 == 0) {
                    stringBuilder.insert(length - 1, " ");
                    editText.setText(stringBuilder.toString());
                    editText.setSelection(editText.getText().length());
                }
            }
        };
    }