ReSharper: Possible NullReferenceException with Enumerator?

Question

ReSharper notifies me about a possible System.NullReferenceException for the following code:

 IEnumerator<IEdgeData> edgeEnumerator = edgeData.GetEnumerator();
 while (edgeEnumerator.MoveNext())
 {
    ConvId fromConvId = edgeEnumerator.Current.From;
    ...
 }

Specifically, it underlines:

edgeEnumerator.Current

I cannot figure out under which circumstances the exception could occur. My understanding is that the while-loops inner statements will only be executed if MoveNext() can set the enumerator on the next element.

score 7 · Accepted Answer · edited May 10 '11 at 14:48

7

The next element could actually be null. For example, the following code:

new List<SampleClass> { null, null, null }

will still give you an enumerator for each element, but the element itself is null.

edited May 10 '11 at 14:48

Cody Gray - on strike

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answered May 10 '11 at 14:35

Tejs

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2

The strange thing is that it doesn't underline anything if we use `foreach` instead. – starteleport Mar 18 '13 at 09:52

ReSharper: Possible NullReferenceException with Enumerator?

1 Answers1