Find out if nested class is zero

Question

I have a class "Data" and a subclass "SubData". I want to access a method in SubData.

In order to do something like:

value = Data.SubData.getValue();

I need to make sure that Data!=null and also that SubData!=null.

I would usually do this:

if (Data!=null)
{
   if (Data.SubData!=null)
   {
       value=Data.SubData.Value();
   }
}

However when I want to print a message in case of Data or SubData being null, I need to put the message in two places:

if (Data!=null)
{
   if (Data.SubData!=null)
   {
       value=Data.SubData.Value();
   }
   else
   {
       // MESSAGE
   }  
}
else
{
    // MESSAGE
}

Is there a way of having //Message only in one place? Of course I could set a "showMessage flag" to true and then later have the message appear only in one place, but then I would still set the flag in two places.

More like a standard programming question than a testing related one ? — Phil Kirkham, Dec 05 '12 at 14:57
Well, it is about good style, I think. Which stackexchange forum would you move it to? — Amelse Etomer, Dec 05 '12 at 14:59
@dzieciou, thank you! Seems like the perfect place for a question like the one above. — Amelse Etomer, Dec 07 '12 at 12:20

score 4 · Accepted Answer · answered Dec 05 '12 at 15:08

4

You could combine the not null tests into one if statement

if (Data != null || Data.SubData != null)
{
    //Do Whatever
}
else
{
    //Message Evaluation Example
    return Data = null ? "Data is null!" : "Data.SubData is null!";
}

Above I have made a check on both Data and Data.SubData to ensure they are not null, if they are however I use a Ternary Operator to figure out which is null and return the result as a string (don't know what data type you would like to return).

This assumes that both properties will never be null, if they are simply expand the evaluation code.

answered Dec 05 '12 at 15:08

Tom

351
1
9

Can I be sure that Data!=null is tested for before Data.SubData!=null? It seems ambiguous to me. – Amelse Etomer Dec 05 '12 at 15:25
Depends what you are after, but in my sample code yes you can be, as it would evaluate left to right. Short-circuiting In If Statement Evaluations, Post From MSDN Forums On If Statement Evaluation Order – Tom Dec 05 '12 at 15:30
Thanks, this is basically what I was after. I just wasn't aware of the term "short circuiting". I'll accept your answer. – Amelse Etomer Dec 05 '12 at 15:40

Find out if nested class is zero

1 Answers1