Evaluate list.contains string in JSTL

Oscar_Reyes_20654 0
Viewed 167838

I need to hide an element if certain values are present in the JSP

The values are stored in a List so I tried:

<c:if test="${  mylist.contains( myValue ) }">style='display:none;'</c:if>

But, it doesn't work.

How can I evaluate if a list contains a value in JSTL, the list and the values are strings.

jstl jsp java
11 Answers
${fn:contains({1,2,4,8}, 2)}

OR

  <c:if test = "${fn:contains(theString, 'test')}">
     <p>Found test string<p>
  </c:if>

  <c:if test = "${fn:contains(theString, 'TEST')}">
     <p>Found TEST string<p>
  </c:if>
user_40938150

If you are using EL 3.0+, the best approach in this case is as this other answer explained in another topic:

For a Collection it's easy, just use the Colleciton#contains() method in EL.

<h:panelGroup id="p1" rendered="#{bean.panels.contains('p1')}">...</h:panelGroup>
<h:panelGroup id="p2" rendered="#{bean.panels.contains('p2')}">...</h:panelGroup>
<h:panelGroup id="p3" rendered="#{bean.panels.contains('p3')}">...</h:panelGroup>

For an Object[] (array), you'd need a minimum of EL 3.0 and utilize its new Lambda support.

<h:panelGroup id="p1" rendered="#{bean.panels.stream().anyMatch(v -> v == 'p1').get()}">...</h:panelGroup>
<h:panelGroup id="p2" rendered="#{bean.panels.stream().anyMatch(v -> v == 'p2').get()}">...</h:panelGroup>
<h:panelGroup id="p3" rendered="#{bean.panels.stream().anyMatch(v -> v == 'p3').get()}">...</h:panelGroup>

If you're not on EL 3.0 yet, you'd need to create a custom EL function. [...]

user_48506460

you must not use fn:contains(), because it is a string comparison. So suppose your list contains 11,12,13 and you have written fn:contains(list,'1'), it will give you the 'true' result. But I am hoping you are expecting false as 1 is not on the list. You should create your own custom tag to use list.contains(Object o).

user_123618820

I found this solution amazing. 

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<%
   ArrayList list = new ArrayList();
   list.add("one");
   list.add("two");
   list.add("three");
%>
<c:set var="list" value="<%=list%>" />
<html>
<body>
        My list is ${list}<br/>
<c:if test='${fn:contains(list, "two")}'>
        My list contains two <br/>
</c:if>
<c:if test='${fn:contains(list, ",")}'>
        My list contains , 
</c:if>
</body>
</html>

The output for the code above is

My list is [one, two, three]

My list contains two

My list contains ,

I hope it helps someone.

user_29315850
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