Enumerator question

[jbricker77]

Long time Java programmer running into a C# issue I can not figure out. I have a class that contains a List. Other classes need iterate through the list. What I have below is not working. I get an excpetion at runtime about Current being outofRange. Should I just return an Enumerator from the List or is there a way to do it like this that I'm missing. thanks for the help. Class Foo { List list; list = fill_it_up(); // fills the list public class FooIterator : IEnumerator { protected int lastVisited; public FooIterator () { lastVisited = -1; } #region IEnumerator Members public object Current { get { return list[lastVisited].thisBar; } } public bool MoveNext() { return ++lastVisited < list.Count - 1; } public void Reset() { throw new Exception("The method or operation is not implemented."); } #endregion } } }

[Josh Smith]

You might as well just return the List's enumerator (accessed via GetEnumerator()) if you are not doing any special/custom processing in your enumerator. Josh

[Robin Panther]

looks like you get an error when lastVisited is -1. Probably you have to do something like this: public object Current { get { if (lastVisited == -1) return null; return list[lastVisited].thisBar; } } ____________________________________________ Robin Panther http://www.robinland.com

[jbricker77]

Just tried this and got an InvalidOperationException saying that the enumeration has either not started or finished.

[jbricker77]

Tried this but did not work. See following post for why and a new question.

[jbricker77]

I think I figured out why I'm having the problem but I still can not figure a way around it yet. FooIterator in an inner class so it can only acess list if list is a static attribute. So I made changes like so: public object Current { get { return Foo.list[lastVisited].thisBar; } But when checking the degugger, when I load Foo.list is is fine. When I access it via the Iterator inner class it is empty. I tried to get rid of the inner class and return the static list and that did not work. What I need to do is immitate the Java Iterator but this seems impossible because of the static attribute contrate on inner classes.

[jbricker77]

The problem is more complex than I wrote here but I will show my solution to this problem. Here is what we had. Class Foo { protected static List<T> list; list = fill_it_up(); // fills the list public class FooIterator : IEnumerator { protected int lastVisited; public FooIterator () { lastVisited = -1; _more enumeration code...._ } The FooIterator was neede by other class to enumerate through the List<>. The inner class was not working because the List has to be static. Class Bar is an object that contains 2 other objects. Here is the change: Class Foo { protected List<Bar> list; list = fill_it_up(); // fills the list public class FooIterator { private List<Bar> list; public FooIterator (List<Bar> anotherList) { list = anotherList; } public IEnumerator<FeFiFoe> GetEnumerator() { foreach (Bar b in list) { // returning the property FeFiFoe object from the Bar object yield return b.thisFeFiFoe; } } } Hope this helps someone else.