Escribir en un EditText tipo tarjeta de crédito

public static void addCreditCardFormat(TextView v, int maxLength) {
    InputFilter filter = new InputFilter.LengthFilter(maxLength);
    v.setFilters(new InputFilter[]{filter});
    v.addTextChangedListener(new TextWatcher() {
        int beforeTextLength = 0;
        int onTextLength = 0;
        boolean isChanged = false;
        // 记录光标的位置
        int location = 0;
        private char[] tempChar;
        private StringBuffer buffer = new StringBuffer();

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            beforeTextLength = s.length();
            if (buffer.length() > 0) {
                buffer.delete(0, buffer.length());
            }
            location = v.getSelectionEnd();
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            onTextLength = s.length();