RE: null scalary type in ScalarMap

• To: Curtis Rueden <curtis@xxxxxxxxxxxxx>
• Subject: RE: null scalary type in ScalarMap
• From: "Kam, Michelle C" <michelle.c.kam@xxxxxxxx>
• Date: Thu, 17 Jul 2003 15:08:09 -0700

Hi Curtis,
 
I'm actually trying to have null values for just the DisplayRealType and
not the ScalarType. I want the possibility for an input field to be
mapped to a null value as one possible visualization instead of *always*
mapping every single input field in the data set to a VisAD parameter. 

However, as I dig further and further into the original code, I'm
finding that I would have to modify many classes to avoid null pointer
exceptions. Am I correct that there would be no simple way to wrap a
null DisplayRealType without getting null pointer exceptions?

Thanks,
Michelle

Michelle Kam           (408) 742-2881
Lockheed Martin Space Systems Co. SSM/ATC/MSIS
B/153 O/L922 
1111 Lockheed Martin Way, Sunnyvale, CA 94089




-----Original Message-----
From: Curtis Rueden [mailto:curtis@xxxxxxxxxxxxx]
Sent: Thursday, July 17, 2003 2:40 PM
To: Kam, Michelle C
Subject: Re: null scalary type in ScalarMap


Hi Michelle,

Intuitively, a ScalarMap with null ScalarType or null DisplayRealType
would serve no purpose when added to a display.  I see no reason to
create
such ScalarMaps.  What are you trying to accomplish?

-Curtis

At 03:50 PM 7/17/2003, you wrote:
>Hello,
>
>I am trying to construct a ScalarMap with a null value as one or both
of the parameters passed in to ScalarMap(ScalarType scalar,
DisplayRealType display_scalar). I tried commenting out the following
code in the ScalarMap constructor:
>
>   /*
>    if (scalar == null && needNonNullScalar) {
>      throw new DisplayException("ScalarMap: scalar is null");
>    }
>    if (display_scalar == null) {
>      throw new DisplayException("ScalarMap: display_scalar is null");
>    }
>*/
>
>However, I will get a null pointer later in that constructor if
"scalar" or "display_scalar" are passed in as null. Is there a way to
wrap a null value for "display_scalar" or "scalar" before it is passed
in to create a ScalarMap? 
>
>Thanks,
>Michelle
>
>Michelle Kam           (408) 742-2881
>Lockheed Martin Space Systems Co. SSM/ATC/MSIS
>B/153 O/L922 
>1111 Lockheed Martin Way, Sunnyvale, CA 94089

• Follow-Ups:
  • RE: null scalary type in ScalarMap
    • From: Bill Hibbard
  • RE: null scalary type in ScalarMap
    • From: Curtis Rueden