The following example demonstrates how to Find Factorial of a Number Using Recursion in JSP. Basically, the following program shows the usage of JSP scriptlet and declaration block to define the function. As can be seen the function find_factorial() uses the recursion to compute the factorial. Also, remember to check whether the user has clicked on submit button or not by using the if statement that indicates that whether the input is null or not. So, you will not get a an ouput of null as soon as you run the code.
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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>Factorial of a Number</title>
</head>
<body>
<form name="f1" method="post" action="5.jsp">
Enter a Number: <input type="text" name="n"/>
<br/>
<input type ="submit" value="Find Factorial"/>
</form>
<%!
int find_factorial(int n)
{
if(n==0)
return 1;
return n*find_factorial(n-1);
}
%>
<%
String inp=request.getParameter("n");
if(inp!=null)
{
int px=Integer.parseInt(inp);
int fact=find_factorial(px);
out.println("<br/>Factorial = " + fact);
}
%>
</body>
</html>Output
