JSTL -- converting string to integer

[maya brown]

how do you convert a string to an integer in JSTL?

here http://osdir.com/ml/jakarta.taglibs.user/2003-12/msg00173.html it says to do:

<c:set var="phNo" value="${1}"/>

to declare an integer, but what if instead of a literal integer there I need to put a param from request? like

<c:set var='phNo' value='${param.pn}' />

I assume ${param.pn} comes in as a string, yes? (just like it would with request.getParameter() ), so how do I convert this to an integer?

I searched long and hard for "JSTL convert string to integer" but did not find much..

essentially I need to do this in JSTL:


String phNo = request.getParameter("pn");
if (phNo == null) {
iPhNo = 1;
} else if (!phNo != null) {
iPhNo = Integer.parseInt(phNo);
}


the answer would be here, http://www.experts-exchange.com/Programming/Languages/Java/J2EE/JSP/Q_21612706.html
but unfortunately you have to pay to see answers here.. this experts-exchange comes up a lot when searching for stuff, it's a bit frustrating..

a lot of entries are different urls for this same thread:
http://mail-archives.apache.org/mod_mbox/jakarta-taglibs-user/200401.mbox/%3Cbt7ibi$7fm$[e-mail]%3E


thank you..

[Paul Clapham]

I don't understand the reason for the question. The expression language will automatically coerce a string to an integer if it's necessary to do so. You don't have to do anything to make that happen. Here's a reference I found with google keywords "jstl convert string to int".

Are you having a specific problem where this doesn't work, or have you not tried it yet because you thought you had to do something?

[maya brown]

oh my gosh, I was hoping my question wouldn't sound too stupid.. what it is is that I'm learning JSTL, and I'm trying to convert all scriptlets in one webapp to JSTL as a learning exercise.. I'm so used to doing back-end with scriptlets, it's a big change... so JSTL will "automatically coerce a string to an integer if it's necessary to do so"?? hmm.... if it's "necessary to do so"?? how does JSTL know if I need to convert a string to an integer?? :~) I saw the url you mention, I probably have seen all JSTL-related pages by now...;~)

here's a conditional I put together yesterday, but it's not working too well...

<!-- example url: ....jsp?pn=9 -- or it might not include the param at all -->

<c:set var='phNo' value='${param.pn}' /> <!-- comes in as string, I assume.. -->
<c:choose>
<c:when test="${phNo == null}">
<c:set var="iPhNo" value="${1}" /> <!-- correct constr for int? -->
</c:when>
<ctherwise>
<c:set var="iPhNo" value='${param.pn}'/> <!-- so this autom. gets converted to an int?? hmmm..-->
</ctherwise>
</c:choose>

<cut value='${iPhNo}'/> <!-- this never prints -->


thank you...

[David Newton]

Please UseCodeTags when posting code or configuration. Unformatted code and configuration is very difficult to read. You can edit your post to include them by using the button.

[Marimuthu Madasamy]

In EL, It would convert a string into a number if it needs to perform any arithmetic operations on that variable. In your case it does not need to since you are just assigning a request parameter value to a variable. But your last c:out should print the value. Have you added the taglib directive for the "c"(core) tag?