Which class implements all the Connection Interfaces which are in javax.microedition.io package and how?

And in the same way which class implements the some of Collection interfaces like Iterator interface. I saw a code: -

Iterator it;
ArrayList list = new ArrayList();

it = list.iterator();

The iterator() return type is "Iterator" which is an interface.

Please tell me what this code is doing is it returning an object of type Iterator? but as far as I know, interface can't be initialized.