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capture check-box value.

Posted on 2004-04-19
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Last Modified: 2007-12-19
How can i capture check-box value from jsp to my servlet.

Initialy on my jsp page, the check-box was not checked. But i cam calling the servlet's constructor when the JSP was shown.

abc.jsp
=====
..
..
  OBScrCCFG3000 theOb =  new OBScrCCFG3000(request);
..
..


abc.java
======
..
..
  public OBScrCCFG3000(HttpServletRequest req) {

        String transaction[] = req.getParameterValues("transaction_category");

        ArrayList al_transaction = null;

       if (transaction.length>0){

       for (int i=0; i<transaction.length;i++){
            al_transaction.add(i,transaction[i]);
        }
        System.out.println("size"+al_transaction.size());

       }
    }
..
..

When i call the abc.jsp. it's show me the transaction is null, thus give me null pointer exception. :-( How can i sovel this?

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Question by:xman19
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3 Comments
 
LVL 92

Accepted Solution

by:
objects earned 600 total points
ID: 10865394
if no checkboxes are checked then i think it will be null, and you should deal with it:

  public OBScrCCFG3000(HttpServletRequest req) {

        String transaction[] = req.getParameterValues("transaction_category");

        ArrayList al_transaction = null;

       if (transaction!=null && transaction.length>0){

       for (int i=0; i<transaction.length;i++){
            al_transaction.add(i,transaction[i]);
        }
        System.out.println("size"+al_transaction.size());

       }
    }
0
 

Author Comment

by:xman19
ID: 10865422
:-)
0
 
LVL 7

Expert Comment

by:searlas
ID: 10867457
You have another NullPointerException problem, which objects has not fixed, al_transaction is null, and will cause a NPE when you attempt to call 'add' on it (and size() if it got that far)

public OBScrCCFG3000(HttpServletRequest req) {
  String transaction[] = req.getParameterValues("transaction_category");

  ArrayList al_transaction = new ArrayList();  
  for ( int i=0; transaction != null && i < transaction.length; i++ ) {
    al_transaction.add(i,transaction[i]);
  }

  System.out.println("size"+al_transaction.size());
}
0

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