if...else within JSP or JSTL
JspIf StatementJstlJsp Problem Overview
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?
Jsp Solutions
Solution 1 - Jsp
>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>
Solution 2 - Jsp
If you just want to output different text, a more concise example would be
${condition ? "some text when true" : "some text when false"}
It is way shorter than c:choose.
Solution 3 - Jsp
The construct for this is:
<c:choose>
<c:when test="${..}">...</c:when> <!-- if condition -->
<c:when test="${..}">...</c:when> <!-- else if condition -->
<c:otherwise>...</c:otherwise> <!-- else condition -->
</c:choose>
If the condition isn't expensive, I sometimes prefer to simply use two distinct <c:if tags - it makes it easier to read.
Solution 4 - Jsp
In case you want to compare strings, write the following JSTL:
<c:choose>
<c:when test="${myvar.equals('foo')}">
...
</c:when>
<c:when test="${myvar.equals('bar')}">
...
</c:when>
<c:otherwise>
...
</c:otherwise>
</c:choose>
Solution 5 - Jsp
<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="val" value="5"/>
<c:choose>
<c:when test="${val == '5'}">
Value is 5
</c:when>
<c:otherwise>
Value is not 5
</c:otherwise>
</c:choose>
Solution 6 - Jsp
simple way :
<c:if test="${condition}">
//if
</c:if>
<c:if test="${!condition}">
//else
</c:if>
Solution 7 - Jsp
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
<%
}
%>
Solution 8 - Jsp
<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="isiPad" value="value"/>
<c:choose>
<!-- if condition -->
<c:when test="${...}">Html Code</c:when>
<!-- else condition -->
<c:otherwise>Html code</c:otherwise>
</c:choose>
Solution 9 - Jsp
<c:if test="${any_cond}" var="condition">
//if part
</c:if>
<c:if test="${!condition}">
//else part
</c:if>
Solution 10 - Jsp
<c:if test="${condition1 && condition2 && condition3}" var="condition">
//if
</c:if>
<c:if test="${!condition}">
//else
</c:if>
This is an another way to take the if condition in a variable.
Solution 11 - Jsp
If you want to do the following by using JSTL Tag Libe, please follow the following steps:
[Requirement] if a number is a grater than equal 40 and lower than 50 then display "Two digit number starting with 4" otherwise "Other numbers".
[Solutions]
1. Please Add the JSTL tag lib on the top of the page.`
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>`
2. Please Write the following code
`
<c:choose>
<c:when test="${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>`
Solution 12 - Jsp
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>
Solution 13 - Jsp
<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>