Question

I have two generic list that have been unioned. Say listA and listB, both of type List<SomeType>.

listA.Union(listB);

The unioned set is of type System.Linq.Enumerable.UnionIterator<string>, which isn’t the same as List<SomeType>.

I have tried casting:

listA.Union(listB).ToList<SomeType>();

and

(List<SomeType>)listA.Union(listB);

Both fail. I tried to access ForEach(), thinking I could add the result to a new list. .Foreach() isn’t available.

I could use a traditional foreach and add each item to a List<SomeType> variable. However, is there a lambda statement that can do the conversion in one line, assigning to a variable of type List<SomeType>?

Answer 1

You don’t have to explicitly cast the List in ToList method. If both the list are of same type, you can simply do ToList in the end to get a List of the same type.

List<MyClass> listA = new List<MyClass>();
List<MyClass> listB = new List<MyClass>();
List<MyClass> temp = listA.Union(listB).ToList(); //Just do ToList at the end. 

Explicitly specifying the type in ToList method should work as well. I am not sure why its not working.