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if...else within JSP or JSTL

I want to output some HTML code based on some condition in a JSP file.

if (condition 1) {
    Some HTML code specific for condition 1
}
else if (condition 2) {
    Some HTML code specific for condition 2
}

How can I do that? Should I use JSTL?

Exampledepot has some nice examples. Have a look > exampledepot.8waytrips.com/egs/javax.servlet.jsp.jstl.core/…
Possible duplicate of How to use if-else option in JSTL

A
Andrea Ligios

Should I use JSTL ?

Yes.

You can use <c:if> and <c:choose> tags to make conditional rendering in jsp using JSTL.

To simulate if , you can use:

<c:if test="condition"></c:if>

To simulate if...else, you can use:

<c:choose>
    <c:when test="${param.enter=='1'}">
        pizza. 
        <br />
    </c:when>    
    <c:otherwise>
        pizzas. 
        <br />
    </c:otherwise>
</c:choose>

Thx for that...Actually I am more into UI dev...So do not have much knowledge of JSTL..Could you please provide me a similar working example of JSTL..I mean for if..else
Thx for the example..The condition I have is actually a JS condition..if navigator.userAgent.match(/iPad/i) != null So can I write that directly in the if test="condition"..
well JSTL will execute at server end it will crate HTML out of it and pass it to client
Ok..that's fine...But for the actual condition i.e.in the test="condition" ...Can I specify any JS condition and if yes, can I write it directly e.g. Can I write
can you update your question with the condition you want to test
K
KIR

If you just want to output different text, a more concise example would be

${condition ? "some text when true" : "some text when false"}

It is way shorter than c:choose.


is this javascript or .jsp?
not working when using a boolean variable as condition any suggest?
Does this need to be enclosed in a special tag, or just paste this directly into HTML?
@otherDewi: It's JSTL, which can be used in a JSP file. The conditional or ternary operator exists in many other languages though, including Javascript.
@bergie3000: No, this is not JSTL. This is EL.
B
Bozho

The construct for this is:

<c:choose>
   <c:when test="${..}">...</c:when> <!-- if condition -->
   <c:when test="${..}">...</c:when> <!-- else if condition -->
   <c:otherwise>...</c:otherwise>    <!-- else condition -->
</c:choose>

If the condition isn't expensive, I sometimes prefer to simply use two distinct <c:if tags - it makes it easier to read.


Can I assume that if first when condition is satisfied, then the second when will not be executed ?
because you get content assist out-of-the-box, for a start. And because webdevs can use it without learning yet-another-dsl
@hop no you cannot
a
aebersold

In case you want to compare strings, write the following JSTL:

<c:choose>
    <c:when test="${myvar.equals('foo')}">
        ...
    </c:when>
    <c:when test="${myvar.equals('bar')}">
        ...
    </c:when>
    <c:otherwise>
        ...
    </c:otherwise>
</c:choose>

I think you can only invoke methods (like .equals) on new(ish) containers, like Tomcat 7+.
H
Hiren Odedra
<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="val" value="5"/>
<c:choose> 
  <c:when test="${val == '5'}">
    Value is 5
  </c:when>
  <c:otherwise>
    Value is not 5
  </c:otherwise>
</c:choose>

M
Milad Heidari

simple way :

<c:if test="${condition}">
    //if
</c:if>
<c:if test="${!condition}">
    //else
</c:if>

S
Shivam

You can write if-else condition inside <% %> in jsp pages and html code outside of <% %>

For example:

   <%
        String username = (String)session.getAttribute("username");
        if(username==null)  {
    %>            
        <p> username is null</p> //html code
    <%
        } else {
    %>
        <p> username is not null</p> //html code
    <%
        }
    %>

Tank you! It was solution for my problem, but this syntax is disgusting.... But thank you again!
a
aristotll
<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="isiPad" value="value"/>
<c:choose>
   <!-- if condition -->
   <c:when test="${...}">Html Code</c:when> 
   <!-- else condition -->
   <c:otherwise>Html code</c:otherwise>   
</c:choose>

S
Sachin Kumar
<c:if test="${any_cond}" var="condition">
    //if part
</c:if>
<c:if test="${!condition}">
    //else part
</c:if>

S
Sachin Kumar
<c:if test="${condition1 && condition2 && condition3}" var="condition">
    //if
</c:if>
<c:if test="${!condition}">
    //else
</c:if>

This is an another way to take the if condition in a variable.


u
user3466950

If you want to do the following by using JSTL Tag Libe, please follow the following steps:

[Requirement] if a number is a grater than equal 40 and lower than 50 then display "Two digit number starting with 4" otherwise "Other numbers".

[Solutions]

1. Please Add the JSTL tag lib on the top of the page.`
     <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>`

2. Please Write the following code
`
<c:choose>
       <c:when test="${params.number >=40 && params.number <50}">
              <p> Two digit number starting with 4. </p>
       </c:when>
       <c:otherwise>
              <p> Other numbers. </p>
       </c:otherwise>
  </c:choose>`

C
Codekie

In case you want to compare strings, write the following JSTL :

<c:choose>
    <c:when test="${myvar.equals('foo')}">
        ...
    </c:when>
    <c:when test="${myvar.equals('bar')}">
        ...
    </c:when>
    <c:otherwise>
        ...
    </c:otherwise>
</c:choose>

A
Aman Kumar
<c:choose>
<c:when test="${not empty userid and userid ne null}">
      <sql:query dataSource="${dbsource}" var="usersql">
                SELECT * FROM newuser WHERE ID = ?;
                <sql:param value="${param.userid}" />
      </sql:query>
 </c:when>
 <c:otherwise >
       <sql:query dataSource="${dbsource}" var="usersql">
                 SELECT * FROM newuser WHERE username = ?;
                 <sql:param value="${param.username}" />
       </sql:query>                              
  </c:otherwise>


It may provide the solution but please consider adding some details with code