Drop down menu and null pointer exception

Question

I am trying to build a drop down menu that gives you options on sorting a list (eg. it sorts on the Title) . The drop down must show which sort option has been selected after the sort occurs.
I keep getting a "java.lang.NullPointerException". I realize this error arises from not assigning a variable to a specific object in java. I'm a .net developer who got thrown into customixing a java application and I just don't see the error. The error message didn't say on which line this occured but it is in the posted code.
It worked for a while and now i gives me this error.
Can someone help me please!?!?
<%String     strCheck = new String("");%>                     </td>
                <form action="ChangeSorting.jsp?recordView=<jsp:getProperty name='CumulusBean' property='recordView'/>" id="changeSortingForm" target="invisibleFrame" method="POST">
                     <td>
               <select name="uid" size="1" onChange="document.getElementById('changeSortingForm').submit();">
               <%if (session.getAttribute( "theUid" ).equals ("{1e58eab1-f625-4d6b-be82-ef0ea493cb7a}"))  {
               strCheck = ("selected");
                }%>
          <option value="{1e58eab1-f625-4d6b-be82-ef0ea493cb7a}"<%=strCheck%> >
            Title          </option>
</form>     Thanks,
Luis

Answer 1

This is not JSF ..
Anyway, it looks like that the following code returns nullsession.getAttribute( "theUid" )and invoking the equals() on it thus causes a NullPointerException.
So check if this attribute really exists in the session and add a nullpointer check to the code. For example:if (session.getAttribute("theUid") != null && session.getAttribute("theUid").equals("blah")) { }