when null!=null (jsp)

[kreplech]

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)
out.print("::"+thisString_sent);


%>

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

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?

thanks!
newb

[graviton]

<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?

[smcneill]

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.