displaying a list of entities in jsp file by using java

Question

I am trying to display list of entities in a .jsp file, but I this error:

Unable to compile class for JSP: 

An error occurred at line: 28 in the jsp file: /gues         


        

Answer 1

You shouldn't be using scriptlets (those oldschool <% %> things with Java code) at all when using servlets and EL. Use taglibs like JSTL instead. It offers the <c:forEach> tag to iterate over a collection.

For example,

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
...
<table border="1">
  <tr>
    <th>Drug Names</th>
    <th>Target Names</th>
  </tr>
  <c:forEach items="${drugtargets}" var="drugtarget">
    <tr>
      <td>${fn:escapeXml(drugtarget.drug)}</td>
      <td>${fn:escapeXml(drugtarget.target)}</td>
    </tr>
  </c:forEach>
</table>

(note that I also fixed the rendering of table rows by putting the <tr> inside the loop)

Much simpler, isn't it? You can by the way also just use <c:out value="${drugtarget.drug}"/> instead of those functions.

If you can, I suggest to add the following to your webapp's web.xml in order to disable scriptlets altogether so that you will be forced to do things the right way.

<jsp-config>
    <jsp-property-group>
        <url-pattern>*.jsp</url-pattern>
        <scripting-invalid>true</scripting-invalid>
    </jsp-property-group>
</jsp-config>

See also:

• How to avoid Java code in JSP files?

Answer 2

In this case "${drugtargets}" is a String, not the list you passed. I would recommend using the looping. It's way cleaner.

<c:forEach var="drugtarget " items="${drugtargets}"> 
.... Your code here ...
</c:forEach>