Android编辑文本屏蔽

我想添加屏蔽......如00000-0000000-0

etusercnic.addTextChangedListener(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) {
            try {
                String str = s.toString();
                if (s.length() == 5 || s.length() == 13) {
                    str += "-";
                    etusercnic.setText(str);
                    etusercnic.setSelection(str.length());
                }
            } catch (Exception ignored) {
            }
        }

        @Override
        public void afterTextChanged(Editable s) {
        }
    });

当我第一次输入值时,它完美地工作,但是当我删除它放置的任何数字时 - 签名.那我该怎么办..