Null reference Exception unhandled by the user code

Question

I build my solution in visual studio(successfull) and I am trying to run it but for some reason at the following line of code it was throwing the exception I went several articles but there was no exact solution how this could be handled

public static int GetCurrentPolicyClassId()
    {
        **int policyClassId = (int) HttpContext.Current.Session[AppConstants.SK_POLICYCLASSID];**
        return policyClassId;
    }

Something is null there... put a breakpoint over that line, then you can Watch what's going on with data. — Alex
– Alex, Commented Aug 2, 2012 at 14:56

Justin Niessner · Accepted Answer · 2012-08-02 14:56:22Z

3

One of the values in the chain you've called is null. You just need to check before getting the values:

if(HttpContext != null && 
   HttpContext.Current != null &&
   HttpContext.Current.Session != null &&
   HttpContext.Current.Session[AppConstants.SK_POLICYCLASSID] != null)
{
    // Get the value here.
}
else
{
    // Something was null. Either set a default value or throw an Exception
}

answered Aug 2, 2012 at 14:56

Justin Niessner

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Gerald Versluis · Accepted Answer · 2012-08-02 14:57:32Z

0

You should probably check if HttpContext != null && HttpContext.Current != null && HttpContext.Current.Session != null

answered Aug 2, 2012 at 14:57

Gerald Versluis

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Tigran · Accepted Answer · 2012-08-02 14:58:01Z

0

any exception is handled by try/catch (or finally), if that exception is possible to handle in general.

For example StackOverflowException could not be handled.

You need to:

what type of exception is
understand reasons of it
based on this decide if that exception is an exceptional behaviour in your application
if yes, handle it with try/catch if program needs to handle it, or leav program to fail, as the exception recieved is too dangerous and it's better to let to fail everything.
if this is not exceptional behavior, try to handle it with, for example null checks, or whatever...

Hope this helps.

answered Aug 2, 2012 at 14:58

Tigran

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