Resharper thinks that typecast is redundant, but without typecast the code does not work

问题

Iterating JsonData through foreach fetches IDictionary enumerator instead of IList one.

foreach (var jsonEntry in jsonData)

This causes my code to throw an error.

InvalidOperationException: Instance of JsonData is not a dictionary
LitJson.JsonData.EnsureDictionary ()
LitJson.JsonData.System.Collections.Specialized.IOrderedDictionary.GetEnumerator ()
LitJson.JsonData.System.Collections.IDictionary.GetEnumerator ()

Casting the object to IList causes Resharper to issue a warning "Type cast is redundant."

foreach (var jsonEntry in jsonData as IList)

Why does Resharper think the cast is redundant ?

回答1:

Why does Resharper think the cast is redundant ?

If you think this way:

IList is a ICollection and IDictionary is also a ICollection because both of them implement 'ICollection', Resharper's warning should become clear.

来源：https://stackoverflow.com/questions/33258145/resharper-thinks-that-typecast-is-redundant-but-without-typecast-the-code-does