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Is there any way to call toString() on an object with the EL and JSTL? (I need the String representation of an enum as index in a map in a JSP EL expression.) I hoped something like ${''+object} would work like in java, but EL isn't that nice, and there does not seem to be any function that does it.
Clarification: I have a variable somemap that maps Strings to Strings, and I have a variable someenum that is an enumeration. I'd like to do something like ${somemap[someenum.toString()]}. (Of course .toString() does not work, but what does?)
459
You just do it like this:
${object}
And it'll toString it for you.
edit: Your nested expression can be resolved like this:
<c:set var="myValue">${someenum}</c:set>
${somemap[myValue]}
The first line stringifies (using toString()) the ${someenum} expression and stores it in the myValue variable. The second line uses myValue to index the map.
175
Couple things you can do.
One, you can use c:set -
<c:set var="nowAString">${yourVar}</c:set>
Another thing you can do is create your own EL function, call it toString, and then call that in JSTL. EL functions are basically static methods hooked up with a taglib file. Straightforward to do.
Edit:
Really? Did you actually, you know, try it?
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%@taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<h1>Hello World!</h1>
<%
pageContext.setAttribute("testDate", new java.util.Date());
%>
<c:set var="myVar">${testDate}</c:set>
testDate = ${testDate}<br/>
myVar = ${myVar}<br/>
testDate Class = ${testDate.class}<br/>
myVar Class = ${myVar.class}<br/>
</body>
</html>
And JSP 2.0 tagfile and JSTL functions are trivial.
38
I think in new versions of JSP api you can call methods, even with parameters!
I just tried ${statusColorMap[jobExecution.exitStatus.toString()]} and it works fine!
3
The answer of Will Hartung should work. Here's a copy'n'paste'n'runnable SSCCE:
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!doctype html>
<%!
enum MyEnum {
FOO, BAR
}
%>
<%
request.setAttribute("myEnum", MyEnum.FOO);
java.util.Map<String, String> map = new java.util.HashMap<String, String>();
map.put("FOO", "value of key FOO");
map.put("BAR", "value of key BAR");
request.setAttribute("map", map);
%>
<html lang="en">
<head>
<title>Test</title>
</head>
<body>
<p>Map: ${map}
<p>Enum: ${myEnum}
<c:set var="myEnumAsString">${myEnum}</c:set>
<p>Map value: ${map[myEnumAsString]}
</body>
</html>
This yields:
Map: {BAR=value of key BAR, FOO=value of key FOO}
Enum: FOO
Map value: value of key FOO
(scriptlets are just for quick prototyping, don't use them in real!)
1
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