Question

What does the following code do? Can the LinkedHashSet be replaced with a HashSet?

public class CollectionFunction {
    public <E> List<E> function(List<E> list) {
        return new ArrayList<E>(new LinkedHashSet<E>(list));
    }
}

Answer 1

What does the following code do?

It seems like it is used to remove duplicates from a list without changing the order

1. removes duplicates (LinkedHashSet is a Set)
2. maintains insertion order (LinkedHashSet has predictable iteration order)
3. convert back to a List

Can the LinkedHashSet be replaced with a HashSet?

No, it will not keep the order guaranteed (#2)