关于'扩展'的泛型的迭代器

Question

public class abc<X extends Z> implements Iterable<X>
{
    protected ArrayList<X> list;

    public Iterator<X> iterator()
    {
        return list.iterator();
    }
}

I get a 'cannot find symbol' error for the iterator method. I have honestly no clue why.

Answer 1

You should give the exact error message, but my guess is that you need to import the Iterator class ( java.util.Iterator ).

Also the way you have declared X requires that you have some other class named Z ( X is restricted to Z or subclasses of Z ). Is this true? If it is, you should rename it as only type parameters should have single-character names. If it's not true, and you are considering Z another type parameter, you would need to declare Z as a type parameter somewhere.