CODEWITHSUNDEEP
c#.netcollections
Raston
Raston

Reputation: 91

How to return ICollection from method?

Consider following method

public ICollection<int> method()
{
    ICollection<int> col = new List<int>();
    return col;
}

HashSet<int> result = (HashSet<int>) method();

Of course I'm getting error "Unable to cast object of type List to HashSet", because I've instantiaded col with List in method()

Is it possible to have generic method, which return ICollection and can be casted at HashSet or List, depending on my needs?

Upvotes: 0

Views: 3007

Answers (1)

Gjeltema
Gjeltema

Reputation: 4166

No, you can't straight cast it because the instance returned is not a HashSet or anything but a List, but you can easily use the ICollection instance returned to initialize a new instance of whatever you need. For example:

ICollection<int> result = Method();
HashSet<int> newHashSet = new HashSet<int>(result);

Upvotes: 2

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