Iterator is a structure that permits iteration over elements of type
Any class with matching
next() fields is considered an
and can then be used e.g. in
for-loops. This makes it easy to implement
Returns the current item of the
Iterator and advances to the next one.
This method is not required to check
hasNext() first. A call to this
false yields unspecified behavior.
On the other hand, iterators should not require a call to
before the first call to
next() if an element is available.