Export excel from Java decimal 0 is not working

I am trying to export the excel.when the value is 2.0 from object,in excel sheet it was displaying only 2 it just omit the decimal value.it is working fine when the value us 2.1 ,2.2 etc.

The problem is coming when it is 2.0,3.0.

    StringBuffer sb= new StringBuffer();
        sb.append("2.0");

        HttpServletResponse response = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext()
                .getResponse();
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/ms-excel");
        response.setHeader("Content-Disposition", "attachment;filename=Test.csv");
        response.getOutputStream().write(sb.toString().getBytes(Charset.forName("UTF-8")));
        response.getOutputStream().flush();
        response.getOutputStream().close();
        FacesContext.getCurrentInstance().responseComplete();

Please help me to resolve this problem