All the classes released in Java 2 that implement the collection interface contain an iterator () method, which returns an instance of the Iterator. There's nearly universal support for the Iterator ...

Filtering Iterator nuts and bolts As the filtering Iterator implements the java.util.Iterator interface, it must provide implementations for the methods defined within that interface.

Since the BufferedIterator is an iterator, it implements the java.util.Iterator interface and honors the contracts laid down in that class’s javadoc.

Anyway- its an implementation of a Trie following these interfaces.. It seems to work okay, but I'm not sure how to go about coding the iterator..