Way to check for null value in if condition

Question

I have the following line of code, which is giving me trouble of NPE

   ServeUrl = ((NameValueCollection)ConfigurationManager.GetSection("Servers")).Get(ment);

When I write this in the following way, I no longer get the NPE

  if (ConfigurationManager.GetSection("Servers") != null && ((NameValueCollection)ConfigurationManager.GetSection("Servers")).Get(ment) != null)
                            {
                                ServeUrl = ((NameValueCollection)ConfigurationManager.GetSection("Servers")).Get(ment);
                            }

Somwhow, the above thing does not look good to my eyes. How can I write this in a better way?

Jon Skeet · Accepted Answer · 2012-12-11 10:39:35Z

5

I'd extract a temporary variable:

var section = (NameValueCollection)ConfigurationManager.GetSection("Servers");
if (section != null && section.Get(ment) != null)
{
    ...
}

Or even:

var section = (NameValueCollection)ConfigurationManager.GetSection("Servers");
if (section != null)
{
    var url = section.Get(ment);
    if (url != null)
    {
        ServeUrl = url;
    }
}

What would you want to do if GetSection returned null though? Can you actually keep going?

edited Dec 11, 2012 at 10:39

answered Dec 11, 2012 at 10:24

Jon Skeet

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2 Comments

dowhilefor Over a year ago

Just one thing to add, wouldn't be GetSection() as NameValueCollection be a bit safer? Depending if getSection can return something else than NameValueCollection, which would explain the cast.

Jon Skeet Over a year ago

@dowhilefor: It depends on what you mean by "safer". If it's an error (e.g. in configuration or programming) for GetSection("Servers") to return some other kind of object, then I'm absolutely fine with an exception. It feels like this is the kind of situation which should stop the system coming up, rather than trying to continue.

OneMore · Accepted Answer · 2012-12-31 21:07:47Z

1

!= means not equal to and == means equal to
If you can't use NULL you can use ""

Apply the condition with logic and then even after it is not getting what you want then:

condition will be false and you also used AND logical operator

edited Dec 31, 2012 at 21:07

OneMore

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answered Dec 11, 2012 at 10:30

Talha Akbar

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Comments

bhavya joshi · Accepted Answer · 2020-08-14 15:09:51Z

0

I would have used this(FYI,i haven't tried this in compiler):

 if (ConfigurationManager.GetSection("Servers")?.Get(ment) is NameValueCollection nvc)
                        {
                            ServeUrl = nvc;
                        }

answered Aug 14, 2020 at 15:09

bhavya joshi

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