Sharing variables between servlets

[Chak Terlapu]

Hi,
I have two servlets A and B. When a button in Servlet A has been clicked servlet B gets invoked. I have a string array in servlet A which I want to use in servlet B. Could anyone tell me how I can do it. Is it possible?
Thanks
Chak

[William Brogden]

Assuming both sevlets are in the same application, passing around objects like arrays of strings is what HttpSession objects are for.
Incidently, saying something like:
"When a button in Servlet A has been clicked servlet B gets invoked."
represents sloppy thinking - servlet A may make a HTML page that has a button which can be clicked, but servlet A does not contain a button. You should always keep in mind that a servlet just gets a request and creates a response - any connection between repeated requests has to be created by the programmer.
Bill

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• Java 2 Exam Prep
  
• Java 2 (Exam Cram)
  
• Java Developer's Guide to Servlets and JSP
  
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[Heath Lilley]

2 ways...
1. Before you get to servlet A is it possible to put this String in to the session...

  HttpSession hs = request.getSession(true);
  hs.setAttribute("theKey", theStringArray);
  

Then get the array out of the session in servlet B.

  HttpSession hs = request.getSession(true);
  String[] s = hs.getAttribute("theKey");
  

2. You could try outputing the array into a hidden field in the page so that it gets submitted to servlet B. This is messy and a "bad practice" but it will work...usually.
Hope this helps.
[This message has been edited by Heath Lilley (edited August 21, 2001).]

[Chak Terlapu]

Hi,
Thanks for the reply and I am sorry it was a mistake to mention "When button in Servlet A..." I have another question.
I have two servlets A and B. When a button in HTML page created by Servlet A has been clicked the control goes to another HTML page which contains a button, when clicked invokes servlet B. Now how can I make the control go from Servlet B to servlet A after the doPOst method is executed in Servlet B. The doPOST method in servlet B does a database operation. Can I add a statement at the end of doPOST method such that after executing the database operation the page created by servlet A gets displayed.
Thanks
Chak

[Heath Lilley]

I think i understand your question ...
You want to direct the user to servlet A from servlet B.
If this is what you want to do, you need to look at the following object.method.

response.sendRedirect(); 

You can send the request and response to any servlet/jsp you want by using this method...as long as the servlet/jsp is in the same web application.