Dinesh on Java

Categories: JSTL

JSTL fn:indexOf() Function

JSTL indexOf function returns the index of specified String in target String. The fn:indexOf() function returns the index within a string of a specified substring.

Syntax:
The fn:indexOf() function has following syntax:

int indexOf(java.lang.String, java.lang.String)

JSTL indexOf Function Example-

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>JSTL IndexOf Function Example</title>
</head>
<body>
  <c:out value="${fn:indexOf('Hello', 'llo')}"></c:out>
</body>
</html>

Output: 2

As you can see above, fn:indexOf() takes ‘Hello’ string as an input parameter and return the index of ‘llo’ as a result. If it does not find the specified String, it will return -1.

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<html>
<head>
<title>Using JSTL Functions</title>
</head>
<body>

<c:set var="string1" value="This is first String."/>
<c:set var="string2" value="This <abc>is second String.</abc>"/>

<p>Index (1) : ${fn:indexOf(string1, "first")}</p>
<p>Index (2) : ${fn:indexOf(string2, "second")}</p>

</body>
</html>

This would produce following result:

Index (1) : 8
Index (2) : 13

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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!