Question

I would like to format a number in JSTL in ways it will look like:

<c:set var="num" value="12345678000199"/>
<fmt:formatNumber type="number" value="${num}" pattern=?/>
<!-- desired output: 12.345.678/0001-99 (Brazilian CNPJ [companies' IRS ID])-->

Thanks in advance!!

Answer 1

That’s not possible with standard JSTL tags nor with the standard NumberFormat API which it is using under the covers. You’d need to create a custom JSP tag or EL function for that. You could achieve the job with simple String manipulation methods or even (ab)use Swing’s MaskFormatter:

String cnpj = "12345678000199";
MaskFormatter mf = new MaskFormatter("##.###.###/####-##");
mf.setValueContainsLiteralCharacters(false);
System.out.println(mf.valueToString(cnpj)); // 12.345.678/0001-99

With an EL function you can ultimately end up like this:

<c:out value="${util:formatCnpj(user.cnpj)}" />

For more detail on creating an EL function, see also the bottom of Hidden features of JSP/Servlet.