Escribir en un EditText con formato de tarjeta de crédito

EditText etCreditCard;

TextWatcher creditCardTextWatcher = 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 str = s.toString();
        if (str.length() == 4 || str.length() == 9 || str.length() == 14) {
            etCreditCard.setText(str + "-");
            etCreditCard.setSelection(etCreditCard.getText().length());
        }
    }
};
etCreditCard.addTextChangedListener(creditCardTextWatcher);