when null!=null (jsp)

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Thread: when null!=null (jsp)

  1. #1
    Join Date
    May 2006

    when null!=null (jsp)

    hello all,

    having a little trouble today... i can't test for null correctly. some code:

    String thisString = null;
    String thisString_sent = request.getParameter("thisString");

    if (thisString_sent!=null)


    <form method="post" action="#">
    <input type="button" onclick="form.submit();" value="<%=thisString_sent%>">
    <input type="hidden" name="thisString" id="thisString" value="<%=thisString_sent%>">

    so... request.getParameter("thisString") should receive null from post data and it does as you can see by the button value. so, why does it even enter the if statement? any ideas?


  2. #2
    Join Date
    Feb 2006
    Cologne - Germany
    <input type="hidden" name="thisString" id="thisString" value="<%=thisString_sent%>">
    if thisString_sent is null, this will place the string "null" at this place.
    why don't you just let the jsp print out the value of thisString_sent to debug?

  3. #3
    Join Date
    May 2006
    I have run into that same problem you are having using the Tomcat ServletEngine (3 or 4 times this week infact). I don't know if this is a bug in tomcat's newest release or what. The problem as I have experienced it is that for some reason, using the != null operand in a jsp tag does not work the way it should. My work around was to use if == null { do nothing... } else { do what I need to do. That seems to work just fine.
    Last edited by smcneill; 05-03-2006 at 09:29 AM.

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