JSP page variable values changes per request

Question

The below jsp code is not giving output as expected

<%@page contentType="text/html" pageEncoding="UTF-8" buffer="none" autoFlush="true"%>
<%@page import="java.util.logging.Logger" %>


<%!  
    String test = "Hei you!!!"; 
    String test2="ok done"; 
%>  <%= test = (test + test2)%>

out put: (on sbusequent page refresh)

Hei you!!! ok done
Hei you!!! ok done
Hei you!!! ok done

expecting:(only on each request)

Hei you!!! ok done

I am not sure if the variable 'test' is stored in cache in jsp server or any binding occurs or variable in this case is stored in application/session scope. Any help is appreciable.

Pshemo · Answer 1 · 2014-02-13T04:45:57.103

3

<%! %> is declaration section which means

String test = "Hei you!!!"; 
String test2="ok done";

will be fields in generated from jsp servlet, not local variables in jspService() method so each time you do

<%= test = (test + test2)%>

text field will be concatenated with value from test2.

In other words your code will generate code similar to

public class Problem extends SomeSpecialJSPHttpServlet {

    String test = "Hei you!!!"; 
    String test2 = "ok done"; 

    protected void _jspService(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().print(test = (test + test2));
    }
}

To print only test + test2 don't reassign this result to test so maybe just use

<%= test + test2 %>

edited Feb 13 '14 at 04:45

answered Feb 13 '14 at 04:28

Pshemo

122,468
25
185
269

1

[Here's a reference.](http://docs.oracle.com/javaee/1.3/tutorial/doc/JSPIntro7.html). – Sotirios Delimanolis Feb 13 '14 at 04:35
@Pshemo Thanks.But then how can we declare fields in jspService? – Manojak Feb 13 '14 at 04:36
2

@master32 Get rid of `!`. Use `<% %>`, or even better [avoid putting Java code in JSP](http://stackoverflow.com/questions/3177733/how-to-avoid-java-code-in-jsp-files). – Pshemo Feb 13 '14 at 04:38

score 1 · Answer 2 · answered Feb 13 '14 at 04:36

1

try like this:

<%=(test + test2)%>

answered Feb 13 '14 at 04:36

Ashish Ratan

2,838
1
24
50

Thanks Ayshman.But I am not trying to solve it but know the reason – Manojak Feb 13 '14 at 04:48

JSP page variable values changes per request

2 Answers2