Re: Generics: multiple interfaces as return parameter does not work

Hi all, I have implemented an interface that looks somewhat like this:

public interface LocalOptimizer {
    <X extends List<Node> & RandomAccess> void optimize(final X tour);
    <X extends List<Node> & RandomAccess> X doSomething();
}

The method optimize() requires a class that implements List<Node> and
RandomAccess, for example ArrayList does this. This works great, I can
call it like this:

        optimize(new ArrayList<Node>());

But I cannot use the second method, this code does not compile:

    public <X extends List<Node> & RandomAccess> X doSomething() {
        return new ArrayList<Node>();
    }

I get the error message "Type mismatch: cannot convert from
ArrayList<Node> to X"
Any ideas how I can make this work?

Martin