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
