Question

Why does the following not work in Java? It would work in C#:

public static final List<String> Split(String str, char delimiter)
    {
        if ((str == null) || "".equals(str))
        {
            return new CopyOnWriteArrayList<String>();
        }
    }

I get an error saying this method has to return List. CopyOnWriteArrayList implements the List interface. Why does covariance not apply on return values in Java?

Answer 1

It looks like you’ve forgotten to return a List<String> for the else branch.