Improper use of string?

[phead]

I'm sure this is quite simple, but it defeats me.

I'm using:
String s_param = request.getParameter("PP");

Thats fine, and I can print s_param.

Then
session.setAttribute("S_PARAM_IN", "TEST");

That also fine, and I get get it later and print it, but

session.setAttribute("S_PARAM_IN", s_param);

combining the two fails, it always seems to be null. I assume I'm doing something fundamentally wrong with the string, but being a very new to java I just cannot see it. Anyone care to throw me a bone here?

Cheers

 

[sedj]

Seems OK to me ... how are you retrieving the session attribute ?

 

[phead]

I'm just using

String passed_param= (String) session.getAttribute("S_PARAM_IN");

to get it, as I said using a quoted string in place of the variable works fine, I assumed this line would be okay based on that.

 

[sedj]

The code you use will defintely work - it must be something in between that is causing the s_param to be null before you set the attribute ...

 

[phead]

Hmmmm, your correct, moving the get attribute to directly below the other two lines works, it just doesn't work when in another jsp that is being called.

SO
String s_param = request.getParameter("PP");
session.setAttribute("S_PARAM_IN", s_param);
String X= (String) session.getAttribute "S_PARAM_IN");

works only if the last line is in the same jsp file, but changing s_param to a string "TEST" does pass it between the jsp files. Almost as though I'm just passing a refernce to the string, not its string contents, that why I was wondering If im misusing the string?

 

[sedj]

Of course the "TEST" will work ... the reason the s_param won't save on the other JSP is becasue the request parameter is probably not being passed by you (ie in a html <input> tag) - this is the whole point of using session variables ...

 

[phead]

Sorry I don't understand that are you saying that session parameters are not saved between different jsp files?

 

[sedj]

In the first page, there is a request parameter named "S_PARAM_IN" right, so when you save this in the session, it is not null.

In the second page, you try to also get "S_PARAM_IN" from the request - but there is no such thing because I suspect you have not included it as a <input> tag.

Of course session variables are available between pages - this is the point of them.

These really are basic JSP principals, perhaps you might like to take a reresher course :

http://java.sun.com/developer/onlineTraining/JSPIntro/