contains invalid expression(s): javax.el.ELException:

Question

Error on run time:

index.jsp(12,8) PWC6038: "${sqlStatement == null}" contains invalid expression(s):
javax.el.ELException: Unable to find ExpressionFactory of type:
    org.apache.el.ExpressionFactoryImpl
    org.apache.jasper.JasperException: : javax.el.ELException: Unable to find ExpressionFactory of type: org.apache.el.ExpressionFactoryImpl

Questions:

How would I go about debugging this?
Unable to find ExpressionFactory of type: org.apache.el.ExpressionFactoryImpl <-- what does this mean?

This is what I have

NetBeans IDE 7.3
Tomcat 7.0
MySql connection

This is a simple sql gateway from Murach's book

index.jsp

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 

    <c:if test="${sqlStatement == null}">
        <c:set var="sqlStatment" value="select * from User" />
    </c:if>

    <h1>The SQL Gateway</h1>
    <p>Enter an SQL statement and click the execute button. Then, information about the<br/>
    statement will appear at the bottom of this page.
    </p>

    <p><b>SQL Statement:</b></p>

    <form action="SqlGateway" method="POST">

        <textarea name="sqlStatement" cols="60" rows="8">${sqlStatement}</textarea>
        <br/><br/>
        <input type="submit" value="Execute">

    </form>

    <p><b>SQL result:</b></p>
    <p>${sqlResult}</p>

web.xml

    <servlet>
    <servlet-name>SqlGatewayServlet</servlet-name>
    <servlet-class>sql.SqlGatewayServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>SqlGatewayServlet</servlet-name>
    <url-pattern>/SqlGateway</url-pattern>
</servlet-mapping>

I don't think there is anything wrong with the servlet, but if you need me to post it please let me know.

Looks like a problem with the EL library. Are you developing this project using maven or is it created as a web project? — Luiggi Mendoza, Jul 31 '13 at 19:49
@RomanC what's your point? The application should run fine on both Tomcat 6 and 7. — Luiggi Mendoza, Jul 31 '13 at 19:52
@RomanC because it was the newest.... hummm is there that much a change between tomcat 6 and 7? — Eric Huang, Jul 31 '13 at 19:54
@RomanC yes, but none of those new libraries will make the EL and JSTL code here invalid, so I'll remark that this application **should work** with no problems in both Tomcat 6 and 7. — Luiggi Mendoza, Jul 31 '13 at 19:57
@EricHuang Your JSP looks good, if you have prebuild war file you should run it first, and also post the web.xml, at least will not log to the archives for examples. — Roman C, Jul 31 '13 at 20:02
@RomanC I edited and posted web.xml. Sorry I am a beginner, what do you mean run war file first? Could you be kind and walk me through? or a reference link... thank you — Eric Huang, Jul 31 '13 at 20:11
First of all use maven, then add all jstl dependencies to project — maks, Jul 31 '13 at 20:13
@maks why to use maven? I just copied/pasted this code and dropped in a new JSP and deployed it on my Tomcat 5.5 and run with no problems. And no, I don't use maven at all :). — Luiggi Mendoza, Jul 31 '13 at 20:15
@LuiggiMendoza Could it be something wrong with my el-api.jar file? — Eric Huang, Jul 31 '13 at 20:19
@Luiggi: with maven you will have less problems with dependencies in future — maks, Aug 01 '13 at 13:13
@maks if you know what you're doing, you won't have any problems at all. — Luiggi Mendoza, Aug 01 '13 at 14:04
@maks in order to understand how OP adds/removes libraries to the build path of application. — Luiggi Mendoza, Aug 01 '13 at 16:46

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

2

Could it be something wrong with my el-api.jar file

You should not have any servletcontainer-specific JAR file in your webapp's /WEB-INF/lib. Servletcontainer-specific JAR files are supposed to be already provided by the servlet-container itself.

Look in Tomcat's /lib folder, it already ships internal libraries, JSP, Servlet and EL libraries. You do not need to supply any of them via your webapp. If you still do it, the runtime classpath may end up in a disaster because there are duplicate different versioned libraries. In your specific case, you likely supplied a randomly downloaded EL API via your webapp which didn't match the EL impl found in the runtime classpath and thus the right impl can't be found via the abstract factory pattern.

So, if you get rid of servletcontainer-specific JARs in /WEB-INF/lib, then all should be well. The /WEB-INF/lib should contain only libraries which are specific to the webapp itself and are not already provided by the servletcontainer.

contains invalid expression(s): javax.el.ELException:

1 Answers1

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