In this tutorial you will learn about the JSTL fn indexOf function.
JSTL fn indexOf Example
In this tutorial you will learn about the JSTL fn indexOf function.
To find out the index of the string within a string JSTL provides a method named fn:indexOf(). This function returns the index of the first occurrence of the specified string.
Syntax :
int indexOf(String, String)
This function returns an +ve integer value as an index of the first occurrence of the substring given as the second argument after, searching within the string specified in the first argument of this function and returns -1 if the specified string is not found.
Example :
Here I am giving a simple example which will demonstrate you about the use of JSTL fn:indexOf() function. In this example I have created a JSP page where I have set the value within which the specified string has to be searched for their index. Next I designed a form to take the input from user for the string that they want to know its index. Then checked for the null value of the text input and then used the function fn:indexOf() to find the index of the specified string.
JstlFnIndexOf.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!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 fn:indexOf Example</title>
</head>
<body>
<c:set var="str" value="Devmanuals"/>
<form action="JstlFnIndexOf.jsp">
Input string to find out its index within <b>${str}</b>.<br>
Enter String/char : <input type="text" name="text1"/>
<input type="submit" value="submit"/>
</form>
<%
if(request.getParameter("text1") != null)
{
%>
<c:set var="searchString" value="${param.text1}"/>
<p>Index of "${searchString}" is : ${fn:indexOf(str, searchString)}</p>
<%
}
%>
</body>
</html>
How to run this example
Here I am using an IDE Eclipse so I am giving the process of executing this example in perspective of Eclipse. Before executing this example you will have needed to add the following jar files :
- jstl.jar
- standard.jar
After adding of these jar files you may execute your program in the following ways :
- Select JstlFnIndexOf.jsp file of your project in Project Explorer -> RightClick -> Run As -> Run On Server -> Choose your server -> Finish.
- On the Eclipse Editor go to your JstlFnIndexOf.jsp -> RightClick -> Run As -> Run On Server -> Choose your server -> Finish.
- Go to Run button look at the toolbar in green color and click -> Choose your server -> Finish.
- A simplest way to execute the example in Eclipse is to use the CTRL+F11 key -> Run On Server -> Choose your server -> Finish
NOTE : In all of the above execution processes you may start the server first and stop the server each time after the execution if not, each time you will may prompted to a dialog box to Restart the server in Eclipse.
Output :
When the execution process will be completed successfully you will get the output on your eclipse browser as follows :
1.1 When you will input the value as follows :
1.2 After clicking on submit button you will get the index value of entered string/character as follows :
2.1 When you will input the value as follows :
2.2 After clicking on submit button you will get the output as follows :
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