Dinesh on Java

Categories: JSTL

JSTL fn:length() Function

In this tutorial you will learn about the JSTL fn length function.

JSTL Length function is used to get the size of a collection or length of a String.

length function, however the size() method is defined by the java.util.Collection interface can not be accessed through the JSP EL because the JavaBeans component design pattern is not confirmed by it for the properties, is used for finding out the how many characters (including the white space) are there in a string or how many items are there in a collection.

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

int length(java.lang.Object)

JSTL Length 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 Length Function Example</title>
</head>
<body>
  <c:out value="${fn:length('Hello')}"></c:out>
</body>
</html>

Output: 5

As you can see above, JSTL Length Function takes ‘Hello’ string as an input parameter and will return 5 as a result.

<%@ 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 is second String." />

<p>Length of String (1) : ${fn:length(string1)}</p>
<p>Length of String (2) : ${fn:length(string2)}</p>

</body>
</html>

This would produce following result:

Length of String (1) : 21
Length of String (2) : 22

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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!