interface Parent<T extends Parent<T>> extends Iterable<T> {
}
interface Child<T extends Child<T>> extends Parent<T> {
}
class ParentImpl implements Parent<ParentImpl> {
public Iterator<ParentImpl> iterator() {
List<ParentImpl> list = new ArrayList<ParentImpl>();
list.add(new ParentImpl());
return list.iterator();
}
}
class ChildImpl implements Child<ChildImpl> {
public Iterator<ChildImpl> iterator() {
List<ChildImpl> list = new ArrayList<ChildImpl>();
list.add(new ChildImpl());
return list.iterator();
}
}
public class Tester {
public static void main(String[] args) {
Parent<ParentImpl> parent = new ParentImpl();
for (ParentImpl p2 : parent) {
System.out.println("> " + p2);
for (Parent<ParentImpl> p3 : p2) {
System.out.println(">> " + p3);
}
}
ParentImpl p = parent.iterator().next();
ChildImpl child = new ChildImpl();
for (ChildImpl c2 : child) {
System.out.println("> " + c2);
for (ChildImpl c3 : c2) {
System.out.println(">> " + c3);
}
}
ChildImpl c = child.iterator().next();
}
}
On Jan 28, 10:11 pm, Christian Catchpole <christ...@catchpole.net>
wrote:
> My brain hurts. I love Iterable, In this example, I'm trying to
> define a Parent interface which iterates a sub-list of it's self
> type. But I want to be able to inherit to Child and change the
> Iterator to Child. Which in theory should work because Child is a sub
> class of Parent. I would expect any code which can operate on Child,
> be able to operate on Parent.
>
> My IDE thinks the "for (Parent p2 : parent)" loops are valid, but they
> don't compile. I think the problem is I'm not actually implementing
> Parent with any Generic type info.. but I can't find any type
> combinations which work. And I'd prefer to not have the implementor
> need to pass the type info.
>
> interface Parent<T extends Parent<T>> extends Iterable<T> {
>
> }
>
> interface Child<T extends Child<T>> extends Parent<T> {
>
> }
>
> class ParentImpl implements Parent {
> public Iterator<Parent> iterator() {
> List<Parent> list = new ArrayList<Parent>();
> list.add(new ParentImpl());
> return list.iterator();
> }
>
> }
>
> class ChildImpl implements Child {
> public Iterator<Child> iterator() {
> List<Child> list = new ArrayList<Child>();
> list.add(new ChildImpl());
> return list.iterator();
> }
>
> }
>
> public class Tester {
> public static void main(String[] args) {
> Parent parent = new ParentImpl();
> for (Parent p2 : parent) {
> System.out.println("> " + p2);
> for (Parent p3 : p2) {
> System.out.println(">> " + p3);
> }
> }
>
> Parent p = parent.iterator().next();
>
> Child child = new ChildImpl();
> for (Child c2 : child) {
> System.out.println("> " + c2);
> for (Child c3 : c2) {
> System.out.println(">> " + c3);
> }
> }
>
> Child c = child.iterator().next();
> }
>
> }
>
>
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